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696 results on '"Cossaro, A."'

2. Molecular anchoring stabilizes low valence Ni(I)TPP on copper against thermally induced chemical changes

Author

Sturmeit, Henning Maximilian, Cojocariu, Iulia, Jugovac, Matteo, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, Sala, Alessandro, Comelli, Giovanni, Moro, Stefania, Stredansky, Matus, Corva, Manuel, Vesselli, Erik, Puschnig, Peter, Schneider, Claus Michael, Feyer, Vitaliy, Zamborlini, Giovanni, and Cinchetti, Mirko

Subjects
Condensed Matter - Materials Science
Abstract

Many applications of molecular layers deposited on metal surfaces, ranging from single-atom catalysis to on-surface magnetochemistry and biosensing, rely on the use of thermal cycles to regenerate the pristine properties of the system. Thus, understanding the microscopic origin behind the thermal stability of organic/metal interfaces is fundamental for engineering reliable organic-based devices. Here, we study nickel porphyrin molecules on a copper surface as an archetypal system containing a metal center whose oxidation state can be controlled through the interaction with the metal substrate. We demonstrate that the strong molecule-surface interaction, followed by charge transfer at the interface, plays a fundamental role in the thermal stability of the layer by rigidly anchoring the porphyrin to the substrate. Upon thermal treatment, the molecules undergo an irreversible transition at 420 K, which is associated with an increase of the charge transfer from the substrate, mostly localized on the phenyl substituents, and a downward tilting of the latters without any chemical modification

Published
2020
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3. Electron Correlation driven Metal-Insulator transition in Strained and Disordered VO2 films

Author

D'Elia, Alessandro, Grazioli, Cesare, Cossaro, Albano, Li, Bowen, Zou, Chongwen, Rezvani, Javad, Pinto, Nicola, Marcelli, Augusto, and Coreno, Marcello

Subjects
Condensed Matter - Materials Science
Abstract

The Metal-Insulator transition (MIT) in VO2 is characterized by the complex interplay among lattice, electronic and orbital degrees of freedom. In this contribution we investigated the strain-modulation of the orbital hierarchy and the influence over macroscopic properties of the metallic phase of VO2 such as Fermi Level (FL) population and metallicity, i.e., the material ability to screen an electric field, by means of temperature-dependent X-ray Absorption Near Edge Structure (XANES) and Resonant Photoemission spectroscopy (ResPES). We demonstrate that the MIT in strained VO2 is of the Filling Control type, hence it is generated by electron correlation effects. In addition, we show that the MIT in Nanostructured (NS) disordered VO2, where the structural phase transition is quenched, is driven by electron correlation. Therefore a fine tuning of the correlation could lead to a precise control and tuning of the transition features.

Published
2020
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4. Keto-enol tautomerization drives the self-assembly of Leucoquinizarin on Au(111)

Author

Costantini, Roberto, Colazzo, Luciano, Batini, Laura, Stredansky, Matus, Mohammed, Mohammed S. G., Achilli, Simona, Floreano, Luca, Fratesi, Guido, de Oteyza, Dimas G., and Cossaro, Albano

Subjects
Condensed Matter - Materials Science
Abstract

The self-assembly of Leucoquinizarin molecule on Au(111) surface is shown to be characterized by the molecules mostly in their keto-enolic tautomeric form, with evidences of their temporary switching to other tautomeric forms. This reveals a metastable chemistry of the assembled molecules, to be considered for their possible employment in the formation of more complex hetero-organic interfaces

Published
2020
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5. Strain induced orbital dynamics across the Metal Insulator transition in thin VO2/TiO2(001) films

Author

D'Elia, A., Rezvani, S. J., Cossaro, A., Stredansky, M., Grazioli, C., Li, B. W., Zou, C. W., Coreno, M., and Marcelli, A.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

VO2 is a strongly correlated material, which undergoes a reversible metal insulator transition (MIT) coupled to a structural phase transition upon heating (T= 67{\deg} C). Since its discovery the nature of the insulating state has long been debated and different solid-state mechanisms have been proposed to explain its nature: Mott-Hubbard correlation, Peierls distortion or a combination of both. Moreover, still now there is a lack of consensus on the interplay between the different degrees of freedom: charge, lattice, orbital and how they contribute to the MIT. In this manuscript we will investigate across the MIT the orbital evolution induced by a tensile strain applied to thin VO2 films. The strained films allowed to study the interplay between orbital and lattice degrees of freedom and to clarify MIT properties.

Published
2020
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6. Long-term Outcomes with Spinal versus General Anesthesia for Hip Fracture Surgery: A Randomized Trial

Author

Vail, Emily A., Feng, Rui, Sieber, Frederick, Carson, Jeffrey L., Ellenberg, Susan S., Magaziner, Jay, Dillane, Derek, Marcantonio, Edward R., Sessler, Daniel I., Ayad, Sabry, Stone, Trevor, Papp, Steven, Donegan, Derek, Mehta, Samir, Schwenk, Eric S., Marshall, Mitchell, Jaffe, J. Douglas, Luke, Charles, Sharma, Balram, Azim, Syed, Hymes, Robert, Chin, Ki-Jinn, Sheppard, Richard, Perlman, Barry, Sappenfield, Joshua, Hauck, Ellen, Tierney, Ann, Horan, Annamarie D., Neuman, Mark D., Looke, Thomas, Bent, Sandra, Franco-Mora, Ariana, Hedrick, Pamela, Newbern, Matthew, Tadros, Rafik, Pealer, Karen, Vlassakov, Kamen, Buckley, Carolyn, Gavin, Lauren, Gorbatov, Svetlana, Gosnell, James, Steen, Talora, Vafai, Avery, Zeballos, Jose, Hruslinski, Jennifer, Cardenas, Louis, Berry, Ashley, Getchell, John, Quercetti, Nicholas, Hassan, Manal, Bajracharya, Gauasan, Billow, Damien, Bloomfield, Michael, Cuko, Evis, Elyaderani, Mehrun K., Hampton, Robert, Honar, Hooman, Khoshknabi, Dilara, Kim, Daniel, Krahe, David, Lew, Michael M., Maheshwer, Conjeevram B., Niazi, Azfar, Saha, Partha, Salih, Ahmed, de Swart, Robert J., Volio, Andrew, Bolkus, Kelly, DeAngelis, Matthew, Dodson, Gregory, Gerritsen, Jeffrey, McEniry, Brian, Mitrev, Ludmil, Kwofie, M. Kwesi, Belliveau, Anne, Bonazza, Flynn, Lloyd, Vera, Panek, Izabela, Dabiri, Jared, Chavez, Chris, Craig, Jason, Davidson, Todd, Dietrichs, Chad, Fleetwood, Cheryl, Foley, Mike, Getto, Chris, Hailes, Susie, Hermes, Sarah, Hooper, Andy, Koener, Greg, Kohls, Kate, Law, Leslie, Lipp, Adam, Losey, Allison, Nelson, William, Nieto, Mario, Rogers, Pam, Rutman, Steve, Scales, Garrett, Sebastian, Barbara, Stanciu, Tom, Lobel, Gregg, Giampiccolo, Michelle, Herman, Dara, Kaufman, Margit, Murphy, Bryan, Pau, Clara, Puzio, Thomas, Veselsky, Marlene, Apostle, Kelly, Boyer, Dory, Chen Fan, Brenda, Lee, Susan, Lemke, Mike, Merchant, Richard, Moola, Farhad, Payne, Kyrsten, Perey, Bertrand, Viskontas, Darius, Poler, Mark, D’Antonio, Patricia, O’Neill, Greg, Abdullah, Amer, Fish-Fuhrmann, Jamie, Giska, Mark, Fidkowski, Christina, Guthrie, Stuart Trent, Hakeos, William, Hayes, Lillian, Hoegler, Joseph, Nowak, Katherine, Beck, Jeffery, Cuff, Jaslynn, Gaski, Greg, Haaser, Sharon, Holzman, Michael, Malekzadeh, A. Stephen, Ramsey, Lolita, Schulman, Jeff, Schwartzbach, Cary, Azefor, Tangwan, Davani, Arman, Jaberi, Mahmood, Masear, Courtney, Haider, Syed Basit, Chungu, Carolyn, Ebrahimi, Ali, Fikry, Karim, Marcantonio, Andrew, Shelvan, Anitha, Sanders, David, Clarke, Collin, Lawendy, Abdel, Schwartz, Gary, Garg, Mohit, Kim, Joseph, Caruci, Juan, Commeh, Ekow, Cuevas, Randy, Cuff, Germaine, Franco, Lola, Furgiuele, David, Giuca, Matthew, Allman, Melissa, Barzideh, Omid, Cossaro, James, D’Arduini, Armando, Farhi, Anita, Gould, Jason, Kafel, John, Patel, Anuj, Peller, Abraham, Reshef, Hadas, Safur, Mohammed, Toscano, Fiore, Tedore, Tiffany, Akerman, Michael, Brumberger, Eric, Clark, Sunday, Friedlander, Rachel, Jegarl, Anita, Lane, Joseph, Lyden, John P., Mehta, Nili, Murrell, Matthew T., Painter, Nathan, Ricci, William, Sbrollini, Kaitlyn, Sharma, Rahul, Steel, Peter A.D., Steinkamp, Michele, Weinberg, Roniel, Stephenson Wellman, David, Nader, Antoun, Fitzgerald, Paul, Ritz, Michaela, Bryson, Greg, Craig, Alexandra, Farhat, Cassandra, Gammon, Braden, Gofton, Wade, Harris, Nicole, Lalonde, Karl, Liew, Allan, Meulenkamp, Bradley, Sonnenburg, Kendra, Wai, Eugene, Wilkin, Geoffrey, Troxell, Karen, Alderfer, Mary Ellen, Brannen, Jason, Cupitt, Christopher, Gerhart, Stacy, McLin, Renee, Sheidy, Julie, Yurick, Katherine, Chen, Fei, Dragert, Karen, Kiss, Geza, Malveaux, Halina, McCloskey, Deborah, Mellender, Scott, Mungekar, Sagar S., Noveck, Helaine, Sagebien, Carlos, Biby, Luat, McKelvy, Gail, Richards, Anna, Abola, Ramon, Ayala, Brittney, Halper, Darcy, Mavarez, Ana, Rizwan, Sabeen, Choi, Stephen, Awad, Imad, Flynn, Brendan, Henry, Patrick, Jenkinson, Richard, Kaustov, Lilia, Lappin, Elizabeth, McHardy, Paul, Singh, Amara, Donnelly, Joanne, Gonzalez, Meera, Haydel, Christopher, Livelsberger, Jon, Pazionis, Theresa, Slattery, Bridget, Vazquez-Trejo, Maritza, Baratta, Jaime, Cirullo, Michael, Deiling, Brittany, Deschamps, Laura, Glick, Michael, Katz, Daniel, Krieg, James, Lessin, Jennifer, Mojica, Jeffrey, Torjman, Marc, Jin, Rongyu, Salpeter, Mary Jane, Powell, Mark, Simmons, Jeffrey, Lawson, Prentiss, Kukreja, Promil, Graves, Shanna, Sturdivant, Adam, Bryant, Ayesha, Crump, Sandra Joyce, Verrier, Michelle, Green, James, Menon, Matthew, Applegate, Richard, Arias, Ana, Pineiro, Natasha, Uppington, Jeffrey, Wolinsky, Phillip, Gunnett, Amy, Hagen, Jennifer, Harris, Sara, Hollen, Kevin, Holloway, Brian, Horodyski, Mary Beth, Pogue, Trevor, Ramani, Ramachandran, Smith, Cameron, Woods, Anna, Warrick, Matthew, Flynn, Kelly, Mongan, Paul, Ranganath, Yatish, Fernholz, Sean, Ingersoll-Weng, Esperanza, Marian, Anil, Seering, Melinda, Sibenaller, Zita, Stout, Lori, Wagner, Allison, Walter, Alicia, Wong, Cynthia, Orwig, Denise, Goud, Maithri, Helker, Chris, Mezenghie, Lydia, Montgomery, Brittany, Preston, Peter, Schwartz, J. Sanford, Weber, Ramona, Fleisher, Lee A., Mehta, Samir, Stephens-Shields, Alisa J., Dinh, Cassandra, Schwartz, Aron, Chelly, Jacques E., Goel, Shiv, Goncz, Wende, Kawabe, Touichi, Khetarpal, Sharad, Monroe, Amy, Shick, Vladislav, Breidenstein, Max, Dominick, Timothy, Friend, Alexander, Mathews, Donald, Lennertz, Richard, Sanders, Robert, Akere, Helen, Balweg, Tyler, Bo, Amber, Doro, Christopher, Goodspeed, David, Lang, Gerald, Parker, Maggie, Rettammel, Amy, Roth, Mary, White, Marissa, Whiting, Paul, Allen, Brian F.S., Baker, Tracie, Craven, Debra, McEvoy, Matt, Turnbo, Teresa, Kates, Stephen, Morgan, Melanie, Willoughby, Teresa, Weigel, Wade, Auyong, David, Fox, Ellie, Welsh, Tina, Cusson, Bruce, Dobson, Sean, Edwards, Christopher, Harris, Lynette, Henshaw, Daryl, Johnson, Kathleen, McKinney, Glen, Miller, Scott, Reynolds, Jon, Segal, B. Scott, Turner, Jimmy, VanEenenaam, David, Weller, Robert, Lei, Jineli, Treggiari, Miriam, Akhtar, Shamsuddin, Blessing, Marcelle, Johnson, Chanel, Kampp, Michael, Kunze, Kimberly, OʼConnor, Mary, Gaskins, Lakisha J., Looke, Thomas, Tadros, Rafik, Vlassakov, Kamen, Cardenas, Louis, Hassan, Manal, Bolkus, Kelly, Mitrev, Ludmil, Kwofie, M. Kwesi, Dabiri, Jared, Lobel, Gregg, Poler, Mark, Giska, Mark, Sanders, David, Schwartz, Gary, Giuca, Matthew, Tedore, Tiffany, Nader, Antoun, Papp, Stephen, Bryson, Greg, Troxell, Karen, Kiss, Geza, Choi, Stephen, Powell, Mark, Applegate, Richard, Warrick, Matthew, Ranganath, Yatish, Elkassabany, Nabil, Chelly, Jacques E., Hoeft, Mark A., Lennertz, Richard, Sanders, Robert, Allen, Brian F.S., Kates, Stephen, Weigel, Wade, Li, Jinlei, Wijeysundera, Duminda N., Kheterpal, Sachin, Moore, Reneé H., Smith, Alexander K., Tosi, Laura L., Elkassabany, Nabil, Looke, Thomas, Menio, Diane, Mehta, Samir, Fleisher, Lee, Menio, Diane, Hruslinski, Jennifer, Ramsey, Lolita, Gaskins, Lakisha J., Langlois, Christine, Gaskins, Lakisha J., Mezenghie, Lydia, Montgomery, Brittany, Oduwole, Samuel, and Rose, Thomas

Published
2024
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7. Evaluation of molecular orbital symmetry via oxygen-induced charge transfer quenching at a metal-organic interface

Author

Cojocariu, Iulia, Sturmeit, Henning Maximilian, Zamborlini, Giovanni, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, D'Incecco, Enrico, Stredansky, Matus, Vesselli, Erik, Jugovac, Matteo, Cinchetti, Mirko, Feyer, Vitaliy, and Schneider, Claus M.

Subjects
Condensed Matter - Materials Science
Abstract

Thin molecular films under model conditions are often exploited as benchmarks and case studies to investigate the electronic and structural changes occurring on the surface of metallic electrodes. Here we show that the modification of a metallic surface induced by oxygen adsorption allows the preservation of the geometry of a molecular adlayer, giving access to the determination of molecular orbital symmetries by means of near-edge x-ray absorption fine structure spectroscopy, NEXAFS. As a prototypical example, we exploited Nickel Tetraphenyl Porphyrin molecules deposited on a bare and on an oxygen pre-covered Cu(100) surface. We find that adsorbed atomic oxygen quenches the charge transfer at the metal-organic interface but, in contrast to a thin film sample, maintains the ordered adsorption geometry of the organic molecules. In this way, it is possible to disentangle {\pi}* and {\sigma}* symmetry orbitals, hence estimating the relative oscillator strength of core level transitions directly from the experimental data, as well as to evaluate and localize the degree of charge transfer in a coupled system. In particular, we neatly single out the {\sigma}* contribution associated with the N 1s transition to the mixed N 2px,y-Ni 3dx2-y2 orbital, which falls close to the leading {\pi}*-symmetry LUMO resonance.

Published
2019
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8. Enhanced ambient stability of exfoliated black phosphorus by passivation with nickel nanoparticles

Author

Caporali, Maria, Serrano-Ruiz, Manuel, Telesio, Francesca, Heun, Stefan, Verdini, Alberto, Cossaro, Albano, Miglio, Matteo Dal, Goldoni, Andrea, and Peruzzini, Maurizio

Subjects
Physics - Chemical Physics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Since its discovery, the environmental instability of exfoliated black phosphorus (2D bP) has emerged as a challenge that hampers its wide application in chemistry, physics, and materials science. Many studies have been carried out to overcome this drawback. Here we show a relevant enhancement of ambient stability in few-layer bP decorated with nickel nanoparticles as compared to pristine bP. In detail, the behavior of the Ni-functionalized material exposed to ambient conditions in the dark is accurately studied by TEM (Transmission Electron Microscopy), Raman Spectroscopy, and high resolution X-ray Photoemission and Absorption Spectroscopy. These techniques provide a morphological and quantitative insight of the oxidation process taking place at the surface of the bP flakes. In the presence of Ni NPs, the decay time of 2D bP to phosphorus oxides is more than three time slower compared to pristine bP, demonstrating an improved structural stability within twenty months of observation.

Published
2019
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12. Identifying site-dependent reactivity in oxidation reactions on single Pt particles.

Author

Dery, Shahar, Kim, Suhong, Haddad, David, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, TOSTE, F. Dean, and Gross, Elad

Abstract

Catalytic nanoparticles are heterogeneous in their nature and even within the simplest particle various surface sites exist and influence the catalytic reactivity. Thus, detailed chemical information at the nanoscale is essential for understanding how surface properties and reaction conditions direct the reactivity of different surface sites of catalytic nanoparticles. In this work, hydroxyl-functionalized N-heterocyclic carbene molecules (NHCs) were anchored to the surface of Pt particles and utilized as chemical markers to detect reactivity variations between different surface sites under liquid and gas phase oxidizing conditions. Differences in the chemical reactivity of surface-anchored NHCs were identified using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 20 nanometers. By conducting IR nanospectroscopy measurements, along with complementary spatially averaged IR and X-ray spectroscopy measurements, we identified that enhanced reactivity occurred on the particles periphery under both gas and liquid phase oxidizing conditions. Under gas phase reaction conditions the NHCs hydroxyl functional groups underwent preferential oxidization to the acid along the perimeter of the particle. Exposure of the sample to harsher, liquid phase oxidizing conditions induced modification of the NHCs, which was mostly identified at the particles periphery. Analysis of X-ray absorption spectroscopy measurements revealed that exposure of the sample to oxidizing conditions induced aromatization of the NHCs, presumably due to oxidative dehydrogenation reaction, along with reorientation of the NHCs from perpendicular to parallel to the Pt surface. These results, based on single particle measurements, demonstrate the high reactivity of surface sites that are located at the nanoparticles periphery and the influence of reaction conditions on site-dependent reactivity.

Published
2018

13. Oxygen Promoted On‐Surface Synthesis of Polyboroxine Molecules

Author

Toffoli, Daniele, primary, Turco, Elia, additional, Stredansky, Matus, additional, Costantini, Roberto, additional, Dell’Angela, Martina, additional, Floreano, Luca, additional, Goldoni, Andrea, additional, Morgante, Alberto, additional, Kladnik, Gregor, additional, Cvetko, Dean, additional, de Oteyza, Dimas G., additional, Colazzo, Luciano, additional, Mohammed, Mohammed S. G., additional, Sala, Alessandro, additional, Comelli, Giovanni, additional, Africh, Cristina, additional, Fronzoni, Giovanna, additional, Balducci, Gabriele, additional, Stener, Mauro, additional, Ustunel, Hande, additional, and Cossaro, Albano, additional

Published
2024
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14. On-Surface Synthesis of Boroxine-Based Molecules

Author

Elia Turco, Matus Stredansky, Roberto Costantini, Javier A. Martinez, Martina Dell’Angela, Elena Zerbato, Daniele Toffoli, Giovanna Fronzoni, Alberto Morgante, Luca Floreano, and Albano Cossaro

Subjects
boroxine, on-surface synthesis, NEXAFS, STM, functionalization, DFT calculations, Chemistry, QD1-999
Abstract

The on-surface synthesis of boroxine-containing molecules can be a convenient method of introducing specific functionalities. Here, we show the validity of a previously described synthesis protocol on the Au (111) surface by applying it to a different molecular precursor. We study in detail the assembly of the precursor, highlighting possible intermediate stages of the condensation process. We combine scanning tunneling microscopy and X-ray spectroscopies to fully characterize both the morphology and the electronic properties of the system. DFT calculations are presented to assign the main electronic transitions originating the B K-edge absorption spectrum. The study paves the way to a facile strategy for functionalizing a surface with molecules of tailored sizes and compositions.

Published
2021
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15. Light-Induced Charge Accumulation in PTCDI/Pentacene/Ag(111) Heterojunctions

Author

Roberto Costantini, Albano Cossaro, Alberto Morgante, and Martina Dell’Angela

Subjects
organic heterojunction, pump–probe photoemission, exciton dynamics, transient energy level alignment, interface dipole, Chemistry, QD1-999
Abstract

The incorporation of singlet fission (SF) chromophores in solar cells is expected to bring significant increases in the power conversion efficiency thanks to multiexciton generation. However, efficient charge generation in the device is determined by the energy level alignment (ELA) between the active materials, which should favor exciton transport and separation under illumination. By combining ultraviolet photoemission spectroscopy and optical differential reflectance measurements, we determine the ELA in a prototypical SF heterojunction between pentacene (Pc) and perylene-tetracarboxylic-diimide (PTCDI) grown on Ag(111). Time-resolved X-ray photoelectron spectroscopy on such a system reveals light-induced modifications of the ELA; by measuring the transient shift of the core level photoemission lines we observe an accumulation of long-lived holes in the PTCDI within the first hundred picoseconds after the optical pump.

Published
2021
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18. Engaging patients as partners in a multicentre trial of spinal versus general anaesthesia for older adults

Author

Looke, Thomas, Bent, Sandra, Franco-Mora, Ariana, Hedrick, Pamela, Newbern, Matthew, Tadros, Rafik, Pealer, Karen, Marcantonio, Edward, Vlassakov, Kamen, Buckley, Carolyn, Gorbatov, Svetlana, Gosnell, James, Steen, Talora, Vafai, Avery, Zeballos, Jose, Cardenas, Louis, Berry, Ashley, Getchell, John, Quercetti, Nicholas, Sessler, Daniel I., Ayad, Sabry, Hassan, Manal, Ali, Assad, Bajracharya, Gauasan, Billow, Damien, Bloomfield, Michael, Elliott, Kavita, Hampton, Robert, He, Linda, Honar, Hooman, Khoshknabi, Dilara, Kim, Daniel, Minko, Paul, Morris, Adam, Niazi, Azfar, Nutcharoen, Tara, Roberts, Jeffrey, Saha, Partha, Salih, Ahmed, Skolaris, Alexis, Stang, Taylor, Strimbu, Victor, Templeton, Jesse, Volio, Andrew, Wang, Jiayi, Bolkus, Kelly, DeAngelis, Matthew, Dodson, Gregory, Gerritsen, Jeffrey, McEniry, Brian, Mitrev, Ludmil, Kwofie, Kwesi, Bonazza, Flynn, Lloyd, Vera, Panek, Izabela, Dabiri, Jared, Chavez, Chris, Craig, Jason, Davidson, Todd, Dietrichs, Chad, Fleetwood, Cheryl, Foley, Mike, Getto, Chris, Hailes, Susie, Hermes, Sarah, Hooper, Andy, Koener, Greg, Kohls, Kate, Law, Leslie, Lipp, Adam, Losey, Allison, Nelson, William, Nieto, Mario, Rogers, Pam, Rutman, Steve, Scales, Garrett, Sebastian, Barbara, Stanciu, Tom, Lobel, Gregg, Giampiccolo, Michelle, Herman, Dara, Kaufman, Margit, Murphy, Bryan, Pau, Clara, Puzio, Thomas, Veselsky, Marlene, Stone, Trevor, Apostle, Kelly, Boyer, Dory, Fan, Brenda Chen, Lee, Susan, Lemke, Mike, Merchant, Richard, Moola, Farhad, Payne, Kyrsten, Perey, Bertrand, Viskontas, Darius, Poler, Mark, D'Antonio, Patricia, Sheppard, Richard, Abdullah, Amer, Fish-Fuhrmann, Jamie, Giska, Mark, Fidkowski, Christina, Guthrie, Trent, Hakeos, William, Hayes, Lillian, Hoegler, Joseph, Nowak, Katherine, Hymes, Robert, Beck, Jeffery, Cuff, Jaslynn, Gaski, Greg, Haaser, Sharon, Holzman, Michael, Malekzadeh, A. Stephen, Ramsey, Lolita, Schulman, Jeff, Schwartzbach, Cary, Sieber, Frederick, Azefor, Tangwan, Brown, Charles, Davani, Arman, Jaberi, Mahmood, Masear, Courtney, Sharma, Balram, Haider, Syed Basit, Chungu, Carolyn, Ebrahimi, Ali, Fikry, Karim, Gannon, Kerri, Marcantonio, Andrew, Pace, Meredith, Sanders, David, Clarke, Collin, Lawendy, Abdel, Schwartz, Gary, Garg, Mohit, Kim, Joseph, Marshall, Mitchell, Caurci, Juan, Commeh, Ekow, Cuevas, Randy, Cuff, Germaine, Franco, Lola, Furguiele, David, Giuca, Matthew, Allman, Melissa, Barzideh, Omid, Cossaro, James, D'Arduini, Armando, Farhi, Anita, Gould, Jason, Kafel, John, Patel, Anuj, Peller, Abraham, Reshef, Hadas, Safur, Mohammed, Toscano, Fiore, Tedore, Tiffany, Akerman, Michael, Brumberger, Eric, Clark, Sunday, Friedlander, Rachel, Jegarl, Anita, Lane, Joseph, Lyden, John P., Mehta, Nili, Murrell, Matthew T., Painter, Nathan, Ricci, William, Sbrollini, Kaitlyn, Sharma, Rahul, Steel, Peter A.D., Steinkamp, Michele, Weinberg, Roniel, Wellman, David Stephenson, Nader, Antoun, Fitzgerald, Paul, Ritz, Michaela, Papp, Steven, Bryson, Greg, Craig, Alexandra, Farhat, Cassandra, Gammon, Braden, Gofton, Wade, Harris, Nicole, Lalonde, Karl, Liew, Allan, Meulenkamp, Bradley, Sonnenburg, Kendra, Wai, Eugene, Wilkin, Geoffrey, Donegan, Derek, Dinh, Cassandra, Elkassabany, Nabil, Horan, Annamarie, Mehta, Samir, Troxell, Karen, Alderfer, Mary Ellen, Brannen, Jason, Cupitt, Christopher, Gerhart, Stacy, McLin, Renee, Sheidy, Julie, Yurick, Katherine, Carson, Jeffrey, Chen, Fei, Dragert, Karen, Kiss, Geza, Malveaux, Halina, McCloskey, Deborah, Mellender, Scott, Mungekar, Sagar S., Noveck, Helaine, Sagebien, Carlos, Perlman, Barry, Biby, Luat, McKelvy, Gail, Richards, Anna, Azim, Syed, Abola, Ramon, Ayala, Brittney, Halper, Darcy, Mavarez, Ana, Choi, Stephen, Awad, Imad, Flynn, Brendan, Henry, Patrick, Jenkinson, Richard, Kaustov, Lilia, Lappin, Elizabeth, McHardy, Paul, Singh, Amara, Hauck, Ellen, Donnelly, Joanne, Gonzalez, Meera, Haydel, Christopher, Livelsberger, Jon, Pazionis, Theresa, Slattery, Bridget, Vazquez-Trejo, Maritza, Schwenk, Eric, Baratta, Jaime, Deiling, Brittany, Deschamps, Laura, Glick, Michael, Katz, Daniel, Krieg, James, Lessin, Jennifer, Torjman, Marc, Chin, Ki Jinn, Jin, Rongyu, Salpeter, Mary Jane, Powell, Mark, Simmons, Jeffrey, Lawson, Prentiss, Kukreja, Promil, Graves, Shanna, Sturdivant, Adam, Bryant, Ayesha, Crump, Sandra Joyce, Dillane, Derek, Taylor, Michael, Verrier, Michelle, Applegate, Richard, Arias, Ana, Pineiro, Natasha, Uppington, Jeffrey, Wolinsky, Phillip, Sappenfield, Joshua, Gunnett, Amy, Hagen, Jennifer, Harris, Sara, Hollen, Kevin, Holloway, Brian, Horodyski, Mary Beth, Pogue, Trevor, Ramani, Ramachandran, Smith, Cameron, Woods, Anna, Warrick, Matthew, Flynn, Kelly, Mongan, Paul, Ranganath, Yatish, Fernholz, Sean, Ingersoll-Weng, Esperanza, Marian, Anil, Seering, Melinda, Sibenaller, Zita, Stout, Lori, Wagner, Allison, Walter, Alicia, Wong, Cynthia, Magaziner, Jay, Orwig, Denise, Brown, Trina, Dattilo, Jim, Ellenberg, Susan, Feng, Rui, Fleisher, Lee, Gaskins, Lakisha, Goud, Maithri, Helker, Chris, Mezenghie, Lydia, Montgomery, Brittany, Preston, Peter, Stephens, Alisa, Schwartz, J. Sanford, Tierney, Ann, Weber, Ramona, Chelly, Jacques, Goel, Shiv, Goncz, Wende, Kawabe, Touichi, Khetarpal, Sharad, King, Kevin, Kunkel, Frank, Luke, Charles, Monroe, Amy, Shick, Vladislav, Silipo, Anthony, Stehle, Caroline, Szabo, Katherine, Yennam, Sudhakar, Hoeft, Mark, Breidenstein, Max, Dominick, Timothy, Friend, Alexander, Mathews, Donald, Lennertz, Richard, Akere, Helen, Balweg, Tyler, Bo, Amber, Doro, Christopher, Goodspeed, David, Lang, Gerald, Parker, Maggie, Rettammel, Amy, Roth, Mary, Sanders, Robert, White, Marissa, Whiting, Paul, Allen, Brian, Baker, Tracie, Craven, Debra, McEvoy, Matt, Turnbo, Teresa, Kates, Stephen, Morgan, Melanie, Willoughby, Teresa, Weigel, Wade, Auyong, David, Fox, Ellie, Welsh, Tina, Jaffe, J. Douglas, Cusson, Bruce, Dobson, Sean, Edwards, Christopher, Harris, Lynette, Henshaw, Daryl, Johnson, Kathleen, McKinney, Glen, Miller, Scott, Reynolds, Jon, Turner, Jimmy, VanEenenaam, David, Weller, Robert, Akhtar, Shamsuddin, Blessing, Marcelle, Johnson, Chanel, Kampp, Michael, Kunze, Kimberly, Li, Jinlei, O'Connor, Mary, Treggiari, Miriam, Hruslinski, Jennifer, Menio, Diane A., Hymes, Robert A., Langlois, Christine, Gaskins, Lakisha J., and Neuman, Mark D.

Published
2021
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19. Mechanistic insights into on-surface reactions from isothermal temperature-programmed X-ray photoelectron spectroscopy

Author

Grossmann, Lukas, Hocke, Manuela, Galeotti, Gianluca, Contini, Giorgio, Floreano, Luca, Cossaro, Albano, Ghosh, Amit, Schmittel, Michael, Rosén, Johanna, Heckl, Wolfgang M., Björk, Jonas, Lackinger, Markus, Grossmann, Lukas, Hocke, Manuela, Galeotti, Gianluca, Contini, Giorgio, Floreano, Luca, Cossaro, Albano, Ghosh, Amit, Schmittel, Michael, Rosén, Johanna, Heckl, Wolfgang M., Björk, Jonas, and Lackinger, Markus

Abstract

On-surface synthesis often proceeds under kinetic control due to the irreversibility of key reaction steps, rendering kinetic studies pivotal. The accurate quantification of reaction rates also bears potential for unveiling reaction mechanisms. Temperature-Programmed X-ray Photoelectron Spectroscopy (TP-XPS) has emerged as an analytical tool for kinetic studies with splendid chemical and sufficient temporal resolution. Here, we demonstrate that the common linear temperature ramps lead to fitting ambiguities. Moreover, pinpointing the reaction order remains intricate, although this key parameter entails information on atomistic mechanisms. Yet, TP-XPS experiments with a stepped temperature profile comprised of isothermal segments facilitate the direct quantification of rate constants from fitting time courses. Thereby, rate constants are obtained for a series of temperatures, which allows independent extraction of both activation energies and pre-exponentials from Arrhenius plots. By using two analogous doubly versus triply brominated aromatic model compounds, we found that their debromination on Ag(111) is best modeled by second-order kinetics and thus proceeds via the involvement of a second, non-obvious reactant. Accordingly, we propose that debromination is activated by surface supplied Ag adatoms. This hypothesis is supported by Density Functional Theory (DFT) calculations. We foresee auspicious prospects for this TP-XPS variant for further exploring the kinetics and mechanisms of on-surface reactions. The temporal evolution of the reactant concentrations as measured by XPS for different temperature profiles reveals that the debromination of organic molecules on Ag(111) is activated by Ag adatoms., Funding Agencies|Deutsche Forschungsgemeinschaft grant [LA 1842/9-1]; CALIPSOplus from the EU Framework Programme for Research and Innovation HORIZON 2020 [730872]; Swedish Research Council; Goran Gustafsson Foundation for Research in Natural Sciences and Medicine

Published
2024
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24. Mechanistic Insights into On-Surface Reactions from Isothermal Temperature-Programmed X-ray Photoelectron Spectroscopy

Author

Grossmann, Lukas, primary, Hocke, Manuela, additional, Galeotti, Gianluca, additional, CONTINI, GIORGIO, additional, Floreano, Luca, additional, Cossaro, Albano, additional, Ghosh, Amit, additional, Schmittel, Michael, additional, Rosen, J., additional, Heckl, Wolfgang M, additional, Björk, Jonas, additional, and Lackinger, Markus, additional

Published
2024
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26. Relating Energy Level Alignment and Amine-Linked Single Molecule Junction Conductance

Author

Dell'Angela, M., Kladnik, G., Cossaro, A., Verdini, A., Kamenetska, M., Tamblyn, I., Quek, S. Y., Neaton, J. B., Cvetko, D., Morgante, A., and Venkataraman, L.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Using photoemission spectroscopy, we determine the relationship between electronic energy level alignment at a metal-molecule interface and single-molecule junction transport data. We measure the position of the highest occupied molecular orbital (HOMO) relative to the Au metal Fermi level for three 1,4-benzenediamine derivatives on Au(111) and Au(110) with ultraviolet and resonant x-ray photoemission spectroscopy. We compare these results to scanning tunnelling microscope based break-junction measurements of single molecule conductance and to first-principles calculations. We find that the energy difference between the HOMO and Fermi level for the three molecules adsorbed on Au(111) correlate well with changes in conductance, and agree well with quasiparticle energies computed from first-principles calculations incorporating self-energy corrections. On the Au(110) which present Au atoms with lower-coordination, critical in break-junction conductance measurements, we see that the HOMO level shifts further from the Fermi level. These results provide the first direct comparison of spectroscopic energy level alignment measurements with single molecule junction transport data.

Published
2010
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27. Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)

Author

Cudia, C. Castellarin, Vilmercati, P., Larciprete, R., Cepek, C., Zampieri, G., Sangaletti, L., Pagliara, S., Verdini, A., Cossaro, A., Floreano, L., Morgante, A., Petaccia, L., Lizzit, S., Battocchio, C., Polzonetti, G., and Goldoni, A.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

The electronic properties and the molecular orientation of Zn-tetraphenyl-porphyrin films deposited on Si(111) have been investigated using synchrotron radiation. For the first time we have revealed and assigned the fine structures in the electronic spectra related to the HOMOs and LUMOs states. This is particularly important in order to understand the orbital interactions, the bond formation and the evolution of the electronic properties with oxidation or reduction of the porphyrins in supramolecular donor-acceptor complexes used in photovoltaic devices., Comment: text 11 pages, 4 figures submitted for publication

Published
2005
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29. The pseudomorphic to bulk fcc phase transition of thin Ni films on Pd(100)

Author

Rizzi, G. A., Cossaro, A., Petukhov, M., Sedona, F., Granozzi, G., Bruno, F., Cvetko, D., Morgante, A., and Floreano, L.

Subjects
Condensed Matter - Materials Science
Abstract

We have measured the transformation of pseudomorphic Ni films on Pd(100) into their bulk fcc phase as a function of the film thickness. We made use of x-ray diffraction and x-ray induced photoemission to study the evolution of the Ni film and its interface with the substrate. The growth of a pseudomorphic film with tetragonally strained face centered symmetry (fct) has been observed by out-of-plane x-ray diffraction up to a maximum thickness of 10 Ni layers (two of them intermixed with the substrate), where a new fcc bulk-like phase is formed. After the formation of the bulk-like Ni domains, we observed the pseudomorphic fct domains to disappear preserving the number of layers and their spacing. The phase transition thus proceeds via lateral growth of the bulk-like phase within the pseudomorphic one, i.e. the bulk-like fcc domains penetrate down to the substrate when formed. This large depth of the walls separating the domains of different phases is also indicated by the strong increase of the intermixing at the substrate-film interface, which starts at the onset of the transition and continues at even larger thickness. The bulk-like fcc phase is also slightly strained; its relaxation towards the orthomorphic lattice structure proceeds slowly with the film thickness, being not yet completed at the maximum thickness presently studied of 30 Angstrom (i.e. about 17 layers)., Comment: 8 pages, 7 figures

Published
2004
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30. Surfactant-like Effect and Dissolution of Ultrathin Fe Films on Ag(001)

Author

Terreni, S., Cossaro, A., Gonella, G., Mattera, L., Duo', L., Ciccacci, F., Cvetko, D., Floreano, L., Morgante, A., Verdini, A., and Canepa, M.

Subjects
Condensed Matter - Materials Science
Abstract

The phase immiscibility and the excellent matching between Ag(001) and Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field of low dimensionality magnetic systems. Intermixing could be drastically limited at deposition temperatures as low as 140-150 K. The film structural evolution induced by post-growth annealing presents many interesting aspects involving activated atomic exchange processes and affecting magnetic properties. Previous experiments, of He and low energy ion scattering on films deposited at 150 K, indicated the formation of a segregated Ag layer upon annealing at 550 K. Higher temperatures led to the embedding of Fe into the Ag matrix. In those experiments, information on sub-surface layers was attained by techniques mainly sensitive to the topmost layer. Here, systematic PED measurements, providing chemical selectivity and structural information for a depth of several layers, have been accompanied with a few XRD rod scans, yielding a better sensitivity to the buried interface and to the film long range order. The results of this paper allow a comparison with recent models enlightening the dissolution paths of an ultra thin metal film into a different metal, when both subsurface migration of the deposit and phase separation between substrate and deposit are favoured. The occurrence of a surfactant-like stage, in which a single layer of Ag covers the Fe film is demonstrated for films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the formation of two Ag capping layers is also reported. As the annealing temperature was increased beyond 700 K, the surface layers closely resembled the structure of bare Ag(001) with the residual presence of subsurface Fe aggregates., Comment: 4 pages, 3 figures

Published
2004
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31. Computational NEXAFS Characterization of Molecular Model Systems for 2D Boroxine Frameworks

Author

Daniele Toffoli, Elisa Bernes, Albano Cossaro, Gabriele Balducci, Mauro Stener, Silvia Mauri, and Giovanna Fronzoni

Subjects
DFT calculations, X-ray absorption spectroscopy, boroxine network, Chemistry, QD1-999
Abstract

The electronic properties of 2D boroxine networks are computationally investigated by simulating the NEXAFS spectra of a series of molecular models, with or without morphologic defects, with respect to the ideal honeycomb structure. The models represent portions of an irregular 2D boroxine framework obtained experimentally, as supported by the Au(111) surface. The B K-edge NEXAFS spectra are calculated within the transition potential (TP) approximation (DFT-TP). The role of the Au(111) supporting surface on the spectral features has also been investigated by comparing the calculated spectra of a defect-rich model in its free-standing and supported form. The calculated NEXAFS spectra differ from the experimental ones, as the position of the main resonance does not match in the two cases. This finding could suggest the presence of a strong interaction of the 2D boroxine network with the Au substrate, which is not captured in the model calculations. However, good agreement between measured and calculated B K-edge NEXAFS spectra is obtained for a model system, namely, trihydroxy boroxine, in which the B atoms are less screened by the valence electrons compared to the B–B linked boroxine network models considered here. These results suggest catalytic activity in the gold substrate in promoting a weakening or even the breaking of the B–B bond, which is not revealed by calculations.

Published
2022
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32. Quantum size effects in the low temperature layer-by-layer growth of Pb on Ge(001)

Author

Floreano, L., Cvetko, D., Bruno, F., Bavdek, G., Cossaro, A., Gotter, R., Verdini, A., and Morgante, A.

Subjects
Condensed Matter - Materials Science
Abstract

The electronic properties of thin metallic films deviate from the corresponding bulk ones when the film thickness is comparable with the wavelength of the electrons at the Fermi level due to quantum size effects (QSE). QSE are expected to affect the film morphology and structure leading to the low temperature (LT) ``electronic growth'' of metals on semiconductors. In particular, layer-by-layer growth of Pb(111) films has been reported for deposition on Ge(001) below 130 K. An extremely flat morphology is preserved throughout deposition from four up to a dozen of monolayers. These flat films are shown to be metastable and to reorganize into large clusters uncovering the first Pb layer, pseudomorphic to the substrate, already at room temperature. Indications of QSE induced structural variations of the growing films have been reported for Pb growth on Ge(001), where the apparent height of the Pb(111) monatomic step was shown to change in an oscillatory fashion by He atom scattering (HAS) during layer-by-layer growth. The extent of the structural QSE has been obtained by a comparison of the HAS data with X-ray diffraction (XRD) and reflectivity experiments. Whereas step height variations as large as 20 % have been measured by HAS reflectivity, the displacement of the atomic planes from their bulk position, as measured by XRD, has been found to mainly affect the topmost Pb layer, but with a lower extent, i.e. the QSE observed by HAS are mainly due to a perpendicular displacement of the topmost layer charge density. The effect of the variable surface relaxation on the surface vibration has been studied by inelastic HAS to measure the acoustic dispersion of the low energy phonons., Comment: 28 pages (laTex,elsart) and 13 figures (eps); updated references

Published
2002
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33. From pseudomorphic to orthomorphic growth of Fe films on Cu3Au(001)

Author

Bruno, F., Terreni, S., Floreano, L., Cossaro, A., Cvetko, D., Luches, P., Mattera, L., Morgante, A., Moroni, R., Repetto, M., Verdini, A., and Canepa, M.

Subjects
Condensed Matter - Materials Science
Abstract

A few theoretical models predict Fe to display both ferromagnetic and antiferromagnetic phases, depending on the volume of the unit cell. A proper choice of the substrate allows the growth of thin Fe overlayers with structures different from the bcc bulk one. The Cu3Au(001) substrate is a suitable candidate for testing these magnetic properties since it has a lattice parameter (3.75 Angstroms) which lies closer to the ferromagnetic fcc Fe phase (3.66 Angstroms) than to the ferromagnetic bcc phase (4.07 Angstroms). We have investigated Fe films up to 40 Angstroms thickness by means of Grazing Incidence X-Ray Diffraction (GIXRD) and Photo/Auger--Electron Diffraction (ED). The combination of GIXRD and ED allows one to obtain quantitative information on the in--plane spacing "a" from the former technique, and the ratio between the vertical spacing "c" and "a", from the latter one. At low coverage the film grows pseudomorphic to the fcc substrate up to a limit thickness of 8 Angstroms. Above this limit the film is characterized by the coexistence of the pseudomorphic phase with another tetragonally strained phase. The latter phase is shown to fall on the epitaxial curve of tetragonally distorted fcc Fe phase. Finally, above 17 Angstroms the development of a body centered phase "alpha", whose unit cell is rotated of 45 deg. with respect to the substrate one, has been clearly observed. "alpha" is the dominating phase for film thickness higher than 25 Angstroms and its lattice constant evolves towards the orthomorphic phase in strict quantitative agreement with epitaxial curves calculated for the tetragonally distorted bcc iron phase., Comment: 1 new figure, updated references; to be published in Phys. Rev. B

Published
2001
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35. Well-ordered surface metal atoms complexation by deposition of Pd cyclometallated compounds on Ag (1 1 0)

Author

Stojkovska, M, Perilli, D, Eduardo Barcelon, J, Smerieri, M, Carraro, G, Hien Dinh, T, Vattuone, L, Rocca, M, Bracco, G, Dell'Angela, M, Costantini, R, Cossaro, A, Vaghi, L, Papagni, A, DI VALENTIN, C, Savio, L, Marija Stojkovska, Daniele Perilli, Jose Eduardo Barcelon, Marco Smerieri, Giovanni Carraro, Thuy Hien Dinh, Luca Vattuone, Mario Rocca, Gianangelo Bracco, Martina Dell'Angela, Roberto Costantini, Albano Cossaro, Luca Vaghi, Antonio Papagni, Cristiana Di Valentin, Letizia Savio, Stojkovska, M, Perilli, D, Eduardo Barcelon, J, Smerieri, M, Carraro, G, Hien Dinh, T, Vattuone, L, Rocca, M, Bracco, G, Dell'Angela, M, Costantini, R, Cossaro, A, Vaghi, L, Papagni, A, DI VALENTIN, C, Savio, L, Marija Stojkovska, Daniele Perilli, Jose Eduardo Barcelon, Marco Smerieri, Giovanni Carraro, Thuy Hien Dinh, Luca Vattuone, Mario Rocca, Gianangelo Bracco, Martina Dell'Angela, Roberto Costantini, Albano Cossaro, Luca Vaghi, Antonio Papagni, Cristiana Di Valentin, and Letizia Savio

Abstract

In this paper we performed the deposition and self-assembly of a Pd-cyclometallated compound on Ag(1 1 0) surface for the first time. The system is investigated from the morphological and chemical point of view by scanning tunneling microscopy and x-ray photoemission spectroscopy, respectively, and the results are validated by ab-initio calculations. Our combined experimental and theoretical study aims at elucidating the atomistic details of the chemical steps following Pd cyclometallate deposition on the metallic substrate. To do that, we analyze the electronic and chemical properties of the species present on the surface at the end of the preparation process at room temperature and at 150 °C. We observe an unexpected complex chemistry: on one side, the organometallic molecules are found to dissociate into fragments, forming a well-ordered metal–carbon network; on the other side, Pd atoms become buried in the bulk of the metal substrate following metal exchange with surface Ag atoms. The details of this mechanistic study reveal the active role played by the metal substrate in promoting the chemistry of the deposited Pd cyclometallates and could open new perspectives for the application of this class of materials in heterogeneous catalysis.

Published
2022

36. Two-Dimensional Self-Assembly Driven by Intermolecular Hydrogen Bonding in Benzodi-7-azaindole Molecules on Au(111)

Author

Abad, José Luis, Martínez, José I., Gómez, Paula, Más-Montoya, Miriam, Rodríguez, Luis, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, Martín-Gago, José A., Curiel, David, Méndez, Javier, Abad, José Luis, Martínez, José I., Gómez, Paula, Más-Montoya, Miriam, Rodríguez, Luis, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, Martín-Gago, José A., Curiel, David, and Méndez, Javier

Published
2023

37. Well-ordered surface metal atoms complexation by deposition of Pd cyclometallated compounds on Ag (1 1 0)

Author

Marija Stojkovska, Daniele Perilli, Jose Eduardo Barcelon, Marco Smerieri, Giovanni Carraro, Thuy Hien Dinh, Luca Vattuone, Mario Rocca, Gianangelo Bracco, Martina Dell'Angela, Roberto Costantini, Albano Cossaro, Luca Vaghi, Antonio Papagni, Cristiana Di Valentin, Letizia Savio, Stojkovska, Marija, Perilli, Daniele, Eduardo Barcelon, Jose, Smerieri, Marco, Carraro, Giovanni, Hien Dinh, Thuy, Vattuone, Luca, Rocca, Mario, Bracco, Gianangelo, Dell'Angela, Martina, Costantini, Roberto, Cossaro, Albano, Vaghi, Luca, Papagni, Antonio, DI VALENTIN, Cristiana, Savio, Letizia, Stojkovska, M, Perilli, D, Eduardo Barcelon, J, Smerieri, M, Carraro, G, Hien Dinh, T, Vattuone, L, Rocca, M, Bracco, G, Dell'Angela, M, Costantini, R, Cossaro, A, Vaghi, L, Papagni, A, DI VALENTIN, C, and Savio, L

Subjects
Pd cyclometallated compounds, Self-assembly, C-based networks, STM, DFT, Photoemission spectroscopy, C-based network, General Physics and Astronomy, Surfaces and Interfaces, General Chemistry, Condensed Matter Physics, Surfaces, Coatings and Films, Pd cyclometallated compound
Abstract

In this paper we performed the deposition and self-assembly of a Pd-cyclometallated compound on Ag(1 1 0) surface for the first time. The system is investigated from the morphological and chemical point of view by scanning tunneling microscopy and x-ray photoemission spectroscopy, respectively, and the results are validated by ab-initio calculations. Our combined experimental and theoretical study aims at elucidating the atomistic details of the chemical steps following Pd cyclometallate deposition on the metallic substrate. To do that, we analyze the electronic and chemical properties of the species present on the surface at the end of the preparation process at room temperature and at 150 degrees C. We observe an unexpected complex chemistry: on one side, the organometallic molecules are found to dissociate into fragments, forming a well-ordered metal-carbon network; on the other side, Pd atoms become buried in the bulk of the metal substrate following metal exchange with surface Ag atoms. The details of this mechanistic study reveal the active role played by the metal substrate in promoting the chemistry of the deposited Pd cyclometallates and could open new perspectives for the application of this class of materials in heterogeneous catalysis.

Published
2022

39. Corrigendum to “Well-ordered surface metal atoms complexation by deposition of Pd cyclometallated compounds on Ag (1 1 0)” [Appl. Surf. Sci. 606 (2022) 154960]

Author

Stojkovska, Marija, primary, Perilli, Daniele, additional, Barcelon, Jose Eduardo, additional, Smerieri, Marco, additional, Carraro, Giovanni, additional, Dinh, Thuy Hien, additional, Vattuone, Luca, additional, Rocca, Mario, additional, Bracco, Gianangelo, additional, Dell'Angela, Martina, additional, Costantini, Roberto, additional, Cossaro, Albano, additional, Vaghi, Luca, additional, Papagni, Antonio, additional, Di Valentin, Cristiana, additional, and Savio, Letizia, additional

Published
2023
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40. Deciphering Electron Interplay at the Fullerene/Sputtered TiOx Interface: A Barrier-Free Electron Extraction for Organic Solar Cells

Author

Nicolas Casaretto, Dylan Amelot, Hervé Cruguel, Nadine Witkowski, Albano Cossaro, Mehrad Ahmadpour, Luca Floreano, Quim Ros, Morten Madsen, Amelot, D., Ahmadpour, M., Ros, Q., Cruguel, H., Casaretto, N., Cossaro, A., Floreano, L., Madsen, M., and Witkowski, N.

Subjects
Free electron model, Materials science, Fullerene, Organic solar cell, Band gap, interface state, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, light-soaking, organic solar cell, General Materials Science, Electronic band structure, fullerene, gap state, resonant photoemission, titanium dioxide, business.industry, Photovoltaic system, Energy conversion efficiency, 021001 nanoscience & nanotechnology, Acceptor, 0104 chemical sciences, Optoelectronics, 0210 nano-technology, business
Abstract

Organic photovoltaics (OPVs) technology now offers power conversion efficiency (PCE) of over 18% and is one of the main emerging photovoltaic technologies. In such devices, titanium dioxide (TiOx) has been vastly used as an electron extraction layer, typically showing unwanted charge-extraction barriers and the need for light-soaking. In the present work, using advanced photoemission spectroscopies, we investigate the electronic interplay at the interface between low-temperature-sputtered TiOx and C70 acceptor fullerene molecules. We show that defect states in the band gap of TiOx are quenched by C70 while an interfacial state appears. This new interfacial state is expected to support the favorable energy band alignment observed, showing a perfect match of transport levels, and thus barrier-free extraction of charges, making low-temperature-sputtered TiOx a good candidate for the next generation of organic solar cells.

Published
2021
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41. Detection of Spin Polarized Band in VO2/TiO2(001) Strained Films via Orbital Selective Constant Initial State Spectroscopy

Author

Alessandro D’Elia, Cesare Grazioli, Albano Cossaro, Bowen Li, Chongwen Zou, Seyed Javad Rezvani, Augusto Marcelli, and Marcello Coreno

Subjects
strain, spin polarization, VO2, orbital selective, constant initial state, resonant photoemission, Physics, QC1-999
Abstract

The VO2 is a 3d1 electron system that undergoes a reversible metal–insulator transition (MIT) triggered by temperature and characterized by an interplay between orbital, charge and lattice degrees of freedom. The characterization of the MIT features are therefore extremely challenging and powerful investigation tools are required. In this work, we demonstrate how a combination of resonant photoemission and constant initial state (CIS) spectroscopy can be used as an orbital selective probe of the MIT studying three different VO2/TiO2(001) strained films. The CIS spectra of the V 3d and V 3p photo-electrons shows sensitivity to different orbital contribution and the presence of a spin polarized band close to the Fermi level.

Published
2020
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43. Bottom-up synthesis of nitrogen-containing graphene nanoribbons from the tetrabenzopentacene molecular motif

Author

Zhijing Feng, Gregor Bavdek, Wilson Ho, Giovanni Comelli, Peter J. Wagner, Amir Mazaheripour, Albano Cossaro, Gregory Czap, Alberto Morgante, Alon A. Gorodetsky, Alberto Verdini, Luca Floreano, Dean Cvetko, David J. Dibble, Gregor Kladnik, Feng, Zhijing, Mazaheripour, Amir, Dibble, David J., Wagner, Peter, Czap, Gregory, Kladnik, Gregor, Cossaro, Albano, Verdini, Alberto, Floreano, Luca, Bavdek, Gregor, Ho, Wilson, Comelli, Giovanni, Cvetko, Dean, Morgante, Alberto, and Gorodetsky, Alon A.

Subjects
Graphene nanoribbon, Graphene nanoribbons, STM, Materials science, Band gap, Graphene, Nanotechnology, 02 engineering and technology, General Chemistry, Semiconductor device, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, law.invention, law, General Materials Science, bottom up, 0210 nano-technology, Nanoscopic scale
Abstract

Atomically-defined graphene nanoribbons (GNRs), which are narrow strips of graphene that feature a quantum confinement-induced bandgap, have shown great promise for applications in the next generation of semiconductor devices. Although numerous studies have demonstrated the bottom-up synthesis of all-carbon GNRs, a comparatively limited number of reports have focused on the preparation of nitrogen-doped GNRs, with two general types of architectures demonstrated to date. Herein, we describe the design, synthesis, and characterization of a new class of nitrogen-containing GNRs consisting of repeating tetrabenzopentacene molecular subunits. Our findings may afford additional possibilities and opportunities with regard to the directed bottom-up synthesis of heteroatom-doped, carbon-based nanoscale electronics. (C) 2020 Elsevier Ltd. All rights reserved.

Published
2020
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44. Copper-assisted oxidation of catechols into quinone derivatives†

Author

Frédéric Chérioux, Johann Coraux, José I. Martínez, Valérie Guisset, José Angel Martín Gago, Estelle Mazaleyrat, José Abad, Ana Cristina Gómez-Herrero, Albano Cossaro, Simone Lisi, Alberto Verdini, Philippe David, Carlos Sánchez-Sánchez, Luca Floreano, Gomez-Herrero, A. C., Sanchez-Sanchez, C., Cherioux, F., Martinez, J. I., Abad, J., Floreano, L., Verdini, A., Cossaro, A., Mazaleyrat, E., Guisset, V., David, P., Lisi, S., Martin Gago, J. A., Coraux, J., Agence Nationale de la Recherche (France), Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Research Council, Comunidad de Madrid, Centre National de la Recherche Scientifique (France), Consejo Superior de Investigaciones Científicas (España), Martínez, José I., Sánchez Sánchez, Carlos, Martín-Gago, José A., Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Universidad Politecnica de Cartagena, Laboratorio Nazionale TASC (TASC), Consiglio Nazionale delle Ricerche [Roma] (CNR)-INFM, Epitaxie et couches minces (EpiCM), Martínez, José I. [0000-0002-2086-8603], Sánchez Sánchez, Carlos [0000-0001-8644-3766], and Martín-Gago, José A. [0000-0003-2663-491X]

Subjects
Semiquinone, Catechols, Metal nanoparticles, 02 engineering and technology, Cathecols, 010402 general chemistry, Photochemistry, 01 natural sciences, Redox, Intermediate product, chemistry.chemical_compound, Degenerative diseases, Molecule, Catechol, Quinone derivatives, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Substrate (chemistry), General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 3. Good health, 0104 chemical sciences, Quinone, Copper-assisted oxidation, Chemistry, chemistry, Intramolecular force, 0210 nano-technology
Abstract

Catechols are ubiquitous substances often acting as antioxidants, thus of importance in a variety of biological processes. The Fenton and Haber–Weiss processes are thought to transform these molecules into aggressive reactive oxygen species (ROS), a source of oxidative stress and possibly inducing degenerative diseases. Here, using model conditions (ultrahigh vacuum and single crystals), we unveil another process capable of converting catechols into ROSs, namely an intramolecular redox reaction catalysed by a Cu surface. We focus on a tri-catechol, the hexahydroxytriphenylene molecule, and show that this antioxidant is thereby transformed into a semiquinone, as an intermediate product, and then into an even stronger oxidant, a quinone, as final product. We argue that the transformations occur via two intramolecular redox reactions: since the Cu surface cannot oxidise the molecules, the starting catechol and the semiquinone forms each are, at the same time, self-oxidised and self-reduced. Thanks to these reactions, the quinone and semiquinone are able to interact with the substrate by readily accepting electrons donated by the substrate. Our combined experimental surface science and ab initio analysis highlights the key role played by metal nanoparticles in the development of degenerative diseases., This work was supported by the French National Research Agency through contract ORGANI'SO (ANR-15-CE09-0017). A. C. G. H. and J. C. thank Laurence Magaud for fruitful discussion about the simulation of the structure of the molecules. F. C. thanks Sarah Benchabane for fruitful discussion. C. S. S., J. I. M. and J. A. M. G. acknowledge financial support from Spanish MINECO (MAT2017-85089-C2-1-R, RYC-2015-17730, RYC-2018-024364-I), European Research Council (ERC) under contract (ERC-2013-SYG-610256 NANOCOSMOS), Comunidad de Madrid via Programa de Investigación Tecnologías 2018 (FOTOART-CM S2018/NMT-4367), and the innovation program under grant agreements 785219 and 881603 (GrapheneCore2 and GrapheneCore3-Graphene-based disruptive technologies, respectively). E. M. acknowledges financial support from Région Rhône Alpes (ARC6 program) and the Labex LANEF. J. C. and J. A. M. G. acknowledges financial support from CNRS and CSIC via the IEA program (PIC2017-FR4/07981), under the ORGAN'X project.

Published
2020
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45. Mn–Cu Transmetalation as a Strategy for the Assembly of Decoupled Metal–Organic Networks on Sn/Cu(001) Surface Alloys

Author

Alberto Verdini, Silvia Carlotto, J. E. Gayone, S. Schneider, A. Cossaro, Magalí Lingenfelder, P. Machaín, Maurizio Casarin, Hugo Ascolani, Luca Floreano, J. D. Fuhr, Ascolani, H., Machain, P., Fuhr, J. D., Schneider, S., Carlotto, S., Casarin, M., Cossaro, A., Verdini, A., Floreano, L., Lingenfelder, M., and Gayone, J. E.

Subjects
TCNQ, Materials science, MANGANESO, STM, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, purl.org/becyt/ford/1 [https], Metal, Transmetalation, Reactivity (chemistry), Physical and Theoretical Chemistry, elettra, coordination structures, Deposition (law), SUPERFICIES, photoemission, purl.org/becyt/ford/1.3 [https], COORDINACIÓN, 021001 nanoscience & nanotechnology, Copper, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, phthalocyanine, General Energy, chemistry, Chemical engineering, visual_art, visual_art.visual_art_medium, 0210 nano-technology, COORDINATION STRUCTURES, PHTHALOCYANINE, ELETTRA
Abstract

Surface alloying of Cu(001) by Sn deposition is a finely controllable method of tuning the degree of copper reactivity in order to drive the on-surface assembly and synthesis of metal-organic coordination networks. In this work we show that the (32×2)R45° reconstruction of the Sn/Cu(001) surface alloy acts as a weakly interacting substrate ideal for the assembly of rectangular metal-organic networks based on transition metals. As a demonstration, we have grown a two-dimensional coordination network formed by manganese and TCNQ (7,7,8,8-tetracyanoquinodimethane) with 1:1 stoichiometry. In contrast with the same structure grown on Au(111), the use of the Sn/Cu(001) substrate enables a commensurate structure with larger and more regular ordered domains. We show that the formation of a Cu-TCNQ coordination network and subsequent Mn-Cu transmetalation reactions are the key steps of the growth mechanism. Moreover, ab initio density-functional calculations indicate that the system studied in the present work is a unique example of a metal-organic coordination network weakly interacting with the substrate. Fil: Machain, Paloma. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro | Universidad Nacional de Cuyo. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro; Argentina Fil: Schneider, S.. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Carlotto, Silvia. Università di Padova; Italia Fil: Casarin, M.. Università di Padova; Italia Fil: Cossaro, A.. No especifíca; Fil: Verdini, A.. No especifíca; Fil: Floreano, L.. No especifíca; Fil: Lingenfelder, Magalí Alejandra. École Polytechnique Fédérale de Lausanne; Suiza Fil: Gayone, Julio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina Fil: Ascolani, Hugo del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina

Published
2020
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46. Clarifying the Adsorption of Triphenylamine on Au(111): Filling the HOMO-LUMO Gap

Author

Teng Zhang, Pamela H. W. Svensson, Iulia Emilia Brumboiu, Valeria Lanzilotto, Cesare Grazioli, Ambra Guarnaccio, Fredrik O. L. Johansson, Klára Beranová, Marcello Coreno, Monica de Simone, Luca Floreano, Albano Cossaro, Barbara Brena, Carla Puglia, Zhang, T., Svensson, P. H. W., Brumboiu, I. E., Lanzilotto, V., Grazioli, C., Guarnaccio, A., Johansson, F. O. L., Beranová, K., Coreno, M., de Simone, M., Floreano, L., Cossaro, A., Brena, B., and Puglia, C.

Subjects
Triphenylamine, Atom and Molecular Physics and Optics, STM, Physical Chemistry, DFT, Article, NEXAFS, Teoretisk kemi, Physical and Theoretical Chemistry, Au(111), Theoretical Chemistry, Fysikalisk kemi, HOMO-LUMO gap, Molecules, triphenylamine, interface, X-ray absorption near edge spectroscopy, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, electron donor, General Energy, Atom- och molekylfysik och optik, Adsorption, Gold
Abstract

In this article, we analyze the electronic structure modifications of triphenylamine (TPA), a well-known electron donor molecule widely used in photovoltaics and optoelectronics, upon deposition on Au(111) at a monolayer coverage. A detailed study was carried out by synchrotron radiation-based photoelectron spectroscopy, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, scanning tunneling microscopy (STM), and ab initio calculations. We detect a new feature in the pre-edge energy region of the N K-edge NEXAFS spectrum that extends over 3 eV, which we assign to transitions involving new electronic states. According to our calculations, upon adsorption, a number of new unoccupied electronic states fill the energy region between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the free TPA molecule and give rise to the new feature in the pre-edge region of the NEXAFS spectrum. This finding highlights the occurrence of a considerable modification of the electronic structure of TPA. The appearance of new states in the HOMO-LUMO gap of TPA when adsorbed on Au(111) has crucial implications for the design of molecular nanoelectronic devices based on similar donor systems.

Published
2022
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47. Adsorption of glutamic acid on clean and hydroxylated rutile TiO2(110): An XPS and NEXAFS investigation

Author

Giovanni Carraro, Marco Smerieri, Simone Passaglia, Gianangelo Bracco, Luca Vattuone, Mario Rocca, Albano Cossaro, Alberto Verdini, Luca Floreano, Letizia Savio, Carraro, G., Smerieri, M., Passaglia, S., Bracco, G., Vattuone, L., Rocca, M., Cossaro, A., Verdini, A., Floreano, L., and Savio, L.

Subjects
NEXAFS, XPS, General Materials Science, glutamic acid, Condensed Matter Physics
Abstract

Due to its biocompatibility, TiO2 is a relevant material for the study of bio-interfaces. Its electronic and chemical properties are influenced by defects, which mainly consist of oxygen vacancies or adsorbed OH groups and which affect, consequently, also the interaction with biological molecules. Here we report on an x-ray photoemission spectroscopy and near edge adsorption fine structure study of glutamic acid (Glu) adsorption on the rutile TiO2(110) surface, either clean or partially hydroxylated. We show that Glu anchors to the surface through a carboxylate group and that the final adsorption state is influenced by the presence of hydroxyl groups on the surface prior to Glu deposition. Indeed, molecules adsorb both in the anionic and in the zwitterionic form, the former species being favored on the hydroxylated substrate.

Published
2022

48. Probing Intermolecular H-Bonding Interactions in Cyanuric Acid Networks: Quenching of the N K-Edge Sigma Resonances

Author

Valeria Lanzilotto, Daniele Toffoli, Elisa Bernes, Mauro Stener, Elisa Viola, Albano Cossaro, Roberto Costantini, Cesare Grazioli, Roberta Totani, Giovanna Fronzoni, Lanzilotto, V., Toffoli, D., Bernes, E., Stener, M., Viola, E., Cossaro, A., Costantini, R., Grazioli, C., Totani, R., and Fronzoni, G.

Subjects
X-ray electron spectroscopie, H-bond interaction, X-ray electron spectroscopies, Density Functional Theory, Physical and Theoretical Chemistry
Abstract

The electronic characterization of the cyanuric acid both in gas phase and when embedded within an H-bonded scheme forming a monolayer on the Au(111) surface has been performed by means of X-ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The experimental spectra at the N, O, and C K-edges have been assigned with the support of DFT calculations, and the combination between theory and experiment has allowed to us investigate the effect of the H-bonding intermolecular interaction on the spectra. In particular, the H-bond formation in the monolayer leads to a quenching of the N 1s NEXAFS resonances associated with transitions to the sigma empty orbitals localized on the N-H portion of the imide group. On the other hand, the pi* empty states remain substantially unperturbed. From a computational point of view, it has been shown that the DFT-TP scheme is not able to describe the N 1s NEXAFS spectra of these systems, and the configuration mixing has to be included, through the TDDFT approach in conjunction with the range-separated XC CAM-B3LYP functional, to obtain a correct reproduction of the N 1s core spectra.

Published
2022

49. Disproportionation of Nitric Oxide at a Surface-Bound Nickel Porphyrinoid

Author

Matus Stredansky, Stefania Moro, Manuel Corva, Henning Sturmeit, Valentin Mischke, David Janas, Iulia Cojocariu, Matteo Jugovac, Albano Cossaro, Alberto Verdini, Luca Floreano, Zhijing Feng, Alessandro Sala, Giovanni Comelli, Andreas Windischbacher, Peter Puschnig, Chantal Hohner, Miroslav Kettner, Jörg Libuda, Mirko Cinchetti, Claus Michael Schneider, Vitaliy Feyer, Erik Vesselli, Giovanni Zamborlini, Stredansky, M., Moro, S., Corva, M., Sturmeit, H., Mischke, V., Janas, D., Cojocariu, I., Jugovac, M., Cossaro, A., Verdini, A., Floreano, L., Feng, Z., Sala, A., Comelli, G., Windischbacher, A., Puschnig, P., Hohner, C., Kettner, M., Libuda, J., Cinchetti, M., Schneider, C. M., Feyer, V., Vesselli, E., and Zamborlini, G.

Subjects
Porphyrins, 2D Materials, Biomimetic Materials, Disproportionation, Nitrogen Monoxide, Single-Atom Catalysts, Copper, Ferric Compounds, Metals, Oxidation-Reduction, Nickel, Nitric Oxide, Metal, General Chemistry, General Medicine, Physik (inkl. Astronomie), Ferric Compound, Catalysis, Porphyrin, Single-Atom Catalyst, 2D Material, ddc:540, ddc:660, Biomimetic Material
Abstract

Uncommon metal oxidation states in porphyrinoid cofactors are responsible for the activity of many enzymes. The F₄₃₀ and P450nor co-factors, with their reduced NiI- and FeIII-containing tetrapyrrolic cores, are prototypical examples of biological systems involved in methane formation and in the reduction of nitric oxide, respectively. Herein, using a comprehensive range of experimental and theoretical methods, we raise evidence that nickel tetraphenyl porphyrins deposited in vacuo on a copper surface are reactive towards nitric oxide disproportionation at room temperature. The interpretation of the measurements is far from being straightforward due to the high reactivity of the different nitrogen oxides species (eventually present in the residual gas background) and of the possible reaction intermediates. The picture is detailed in order to disentangle the challenging complexity of the system, where even a small fraction of contamination can change the scenario.

Published
2022
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50. Formation of diphenyl-bipyridine units by surface assisted cross coupling in Pd-cyclometalled complexes

Author

Jose Eduardo Barcelon, Marija Stojkovska, Daniele Perilli, Giovanni Carraro, Marco Smerieri, Luca Vattuone, Mario Rocca, Gianangelo Bracco, Martina Dell'Angela, Roberto Costantini, Albano Cossaro, Luca Vaghi, Antonio Papagni, Cristiana Di Valentin, Letizia Savio, Eduardo Barcelon, J, Stojkovska, M, Perilli, D, Carraro, G, Smerieri, M, Vattuone, L, Rocca, M, Bracco, G, Dell'Angela, M, Costantini, R, Cossaro, A, Vaghi, L, Papagni, A, DI VALENTIN, C, and Savio, L

Subjects
History, Polymers and Plastics, Cross coupling reaction, STM, General Physics and Astronomy, Surfaces and Interfaces, General Chemistry, Condensed Matter Physics, DFT, Industrial and Manufacturing Engineering, Surfaces, Coatings and Films, Pd cyclometallated compound, Photoemission spectroscopy, Business and International Management, Surface reconstruction
Abstract

The Pd cyclometallated complex [(5-bromo-2-phenylpyridine)Pd(μ-Cl)]2 is deposited on Ag(1 1 0) at room temperature by sublimation in ultra-high vacuum. The thermal evolution of the system is followed by scanning tunnelling microscopy and X-ray photoemission spectroscopy, while the initial and final configurations are validated by ab-initio calculations. We observe the surface induced dissociation of the molecule and the occurrence of a cross coupling reaction between the two organic fragments, leading to the surface assisted synthesis of diphenyl-bipyridine molecules. Such a process, occurring with low probability at RT, is thermally activated and competes with desorption. At variance with most cross-coupling reactions at surfaces reported in literature, in this case the reactants come from the dissociation of the same compound so that only one precursor is employed, leading to a simplified preparation protocol. The Br and Cl atoms dissociated from the molecule bind to the surface and promote an extended surface reconstruction upon annealing, which was not observed previously upon deposition of halogenated aromatic compounds.

Published
2023
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