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The distribution of molecules between the gas and solid phase during star and planet formation determines the trajectory of gas and grain surface chemistry, as well as the delivery of elements to nascent planets. This distribution is primarily set by the binding energies of different molecules to water ice surfaces. We computationally estimated the binding energies of 10 astrochemically relevant P-bearing species on water surfaces. We also validate our method for 20 species with known binding energies. We used Density Functional Theory (DFT) calculations (M06-2X/aug-cc-pVDZ) to calculate the energetics of molecules and water-molecule clusters (1–3 H2O molecules) and from this determined the binding energy by comparing the complex and the separate molecule and cluster energies. We also explore whether these estimates can be improved by first calibrating our computational method using experimentally measured binding energies. Using the 20 reference molecules we find that the 2H2O cluster size yields the best binding energy estimates and that the application of a calibration to the data may improve the results for some classes of molecules, including more-refractory species. Based on these calculations we find that small P-bearing molecules such as PH3, PN, PO, HPO, PO2, and POOH are relatively volatile and should desorb prior or concomitantly with water ice, while H2PO, HPO2, PO3, and PO2OH can strongly bind to any hydroxylated surface and will likely remain on the interstellar grains surface past the desorption of water ice. The depletion of P carriers on grains constitutes a pathway for the inclusion of phosphorous molecules in planets and planetesimals.

Benzonitrile (c-C6H5CN) has been recently detected in cold and dense regions of the interstellar medium, where it has been used as a signpost of a rich aromatic organic chemistry that might lead to the production of polycyclic aromatic hydrocarbons. One possible origin of this benzonitrile is interstellar ice chemistry involving benzene (c-C6H6) and nitrile molecules (organic molecules containing the −C≡N group). We have addressed the plausibility of this c-C6H5CN formation pathway through laboratory experiments using our new setup SPACE TIGER. The SPACE TIGER experimental setup is designed to explore the physics and chemistry of interstellar ice mantles using laser-based ice processing and product detection methods. We have found that c-C6H5CN is formed upon irradiation of c-C6H6:CH3CN binary ice mixtures with 2 keV electrons and Lyα photons at low temperatures (4−10 K). Formation of c-C6H5CN was also observed when c-C6H6 and CH3CN were embedded in a CO ice matrix, but it was efficiently quenched in a H2O ice matrix. The results presented in this work imply that interstellar ice chemistry involving benzene and nitrile molecules could contribute to the formation of the observed benzonitrile only if these species are present on top of the ice mantles or embedded in the CO-rich ice layer, instead of being mixed into the H2O-rich ice layer.

With the advent of technologies such as ion array detectors and high energy permanent magnet materials, there is renewed interest in the unique focusing properties of the cycloidal mass analyzer and its ability to enable small, high-resolution, and high-sensitivity instruments. However, most literature dealing with the design of cycloidal mass analyzers assumes a single channel detector because at the time of those publications, compatible multichannel detectors were not available. This manuscript introduces and discusses considerations and a procedure for designing cycloidal mass analyzers coupled with focal plane ion array detectors. To arrive at a set of relevant design considerations, we first review the unique focusing properties of the cycloidal mass analyzer and then present calculations detailing how the dimensions and position of the focal plane array detector relative to the ion source determine the possible mass ranges and resolutions of a cycloidal mass analyzer. We present derivations and calculations used to determine the volume of homogeneous electric and magnetic fields needed to contain the ion trajectories and explore the relationship between electric and magnetic field homogeneity on resolving power using finite element analysis (FEA) simulations. A set of equations relating the electric field homogeneity to the geometry of the electric sector electrodes was developed by fitting homogeneity values from 78 different FEA models. Finally, a sequence of steps is suggested for designing a cycloidal mass analyzer employing an array detector.

In 1938, Walker Bleakney and John A. Hipple first described the cycloidal mass analyzer as the only mass analyzer configuration capable of "perfect" ion focusing. Why has their geometry been largely neglected for many years and how might it earn a respectable place in the world of modern chemical analysis? This Perspective explores the properties of the cycloidal mass analyzer and identifies the lack of suitable ion array detectors as a significant reason why cycloidal mass analyzers are not widely used. The recent development of capacitive transimpedance amplifier array detectors can enable several techniques using cycloidal mass analyzers including spatially coded apertures and single particle mass analysis with a "virtual-slit", helping the cycloidal mass analyzer earn a respectable place in chemical analysis.

A series of zinc-based catalysts was evaluated for their efficiency in decomposing formic acid into molecular hydrogen and carbon dioxide in the gas phase using quadrupole ion trap mass spectrometry experiments. The effectiveness of the catalysts in the series [(L)Zn(H)]+ , where L=2,2':6',2''-terpyridine (tpy), 1,10-phenanthroline (phen) or 2,2'-bipyrydine (bpy), was found to depend on the ligand used, which turned out to be fundamental in tuning the catalytic properties of the zinc complex. Specifically, [(tpy)Zn(H)]+ displayed the fastest reaction with formic acid proceeding by dehydrogenation to produce the zinc formate complex [(tpy)Zn(O2 CH)]+ and H2 . The catalysts [(L)Zn(H)]+ are reformed by decarboxylating the zinc formate complexes [(L)Zn(O2 CH)]+ by collision-induced dissociation, which is the only reaction channel for each of the ligands used. The decarboxylation reaction was found to be reversible, since the zinc hydride complexes [(L)Zn(H)]+ react with carbon dioxide yielding the zinc formate complex. This reaction was again substantially faster for L=tpy than L=phen or bpy. The energetics and mechanisms of these processes were modelled using several levels of density functional theory (DFT) calculations. Experimental results are fully supported by the computational predictions.

This work demonstrates a novel approach to mass spectrometry using the “virtual-slit” created by the small, localized volume from which ions are generated by localized ionization techniques such as laser ionization of particles and surfaces, and spark ionization. That is, the volume in which the ions are generated creates a localized source of ions in much the same way as a slit that allows only ions from a specific cross sectional area to pass. As demonstrated in this work, the unique perfect focusing properties of a cycloidal mass analyzer can enable the localized ionization volume to function as a virtual-slit. In this manuscript, we provide a proof-of-concept (POC) demonstration of a virtual-slit cycloidal mass spectrometer (VS-CMS) consisting of a cycloidal mass analyzer, a laser ionization source, and an ion array detector. The laser is used to ionize either bulk or thin film samples of Cu, Ti, Ni, and Cr. Results indicate that the width of the peaks at the detector is the same as the laser spot size, validating the concept of virtual-slit focusing. Furthermore, the Ti and Cu ablated with each laser pulse is estimated at 60 and 140 fg, respectively, indicating that a very low detection limit is possible given the ability of the cycloidal mass analyzer to collect ions generated by laser ionization that have wide energy and angular dispersions. The VS-CMS concept has the potential to enable development of fieldable instruments for chemical, elemental, and isotopic analysis of organic and inorganic samples, that are relatively small compared to currently used laser ionization time-of-flight and laser ablation inductively coupled plasma mass spectrometers.

A new decarbonylation reaction is observed for [(K2-acetate)Pd(K2-diphosphine)]+ complexes. Gas-phase IR experiments identify the product as [CH3Pd(OP(Ph2)CH2PPh2)]+. DFT calculations uncovered a plausible mechanism involving O atom abstraction by the diphosphine ligand within the coordination sphere to yield the acetyl complex, [CH3COPd(OP(Ph2)CH2PPh2)]+, which then undergoes decarbonylation.

The expanding use of emerging synthetic drugs such as synthetic cathinones, or “bath salts”, is a growing public health concern and a continual challenge for drug analysts. In the tandem mass spectra of protonated α-pyrrolidinophenone cathinones, the tropylium ion at m/z 91 is often among the most abundant product ions, but its mechanistic origin is currently unexplained. This project combined electrospray ionization multi-stage mass spectrometry (ESI-MSn), high-resolution mass spectrometry (HRMS), isotopic labeling and ion spectroscopy to enhance our understanding of the fragmentation pathways and mechanisms of a variety of α-pyrrolidinophenone cathinones. The fragmentation trends derived from these ESI-MS/MS studies are: 1) unlike N-alkylated cathinones, abundant radical cations are not observed from even-electron precursors of α-pyrrolidinophenones; 2) the loss of a 71 Da pyrrolidine neutral to form an alkylphenone cation is always observed; 3) a series of neutral alkenes are lost from the alkylphenone cation to form intermediate cations with phthalane-like structures. The phthalane intermediates then eliminate the carbonyl carbon as CO or C2H2O to form a tropylium ion at m/z 91. The α-carbon of the original cathinone is almost exclusively retained in the tropylium ion. If the original cathinone is substituted on the aromatic ring, the observed tropylium ion will be shifted by the mass of the substitution. These findings explain the characteristic ions in ESI-MS/MS spectra of synthetic cathinones and will help analysts better employ mass spectral observations in future casework.

Two pseudohalide thiocyanate ions (SCN � ) have been used to replace two iodides in CH3NH3PbI3, and the resulting perovskite material was used as the active material in solar cells. In accelerated stability tests, the CH3NH3Pb(SCN)2I perovskite films were shown to be superior to the conventional CH3NH3PbI3 films as no significant degradation was observed after the film had been exposed to air with a relative humidity of 95 % for over four hours, whereas CH3NH3PbI3 films degraded in less than 1.5 hours. Solar cells based on CH3NH3Pb(SCN)2I thin films exhibited an efficiency of 8.3 %, which is comparable to that of CH3NH3PbI3 based cells fabricated in the same way. Perovskite-type CH3NH3PbX3 solid-state solar cells with over 19 % efficiency have recently been reported. (1) They represent promising candidates for next-generation photo- voltaic devices owing to their astoundingly high efficiency, the low costs associated with their solution-based fabrication, and tunable optical properties. (2) Furthermore, this material performs very well in terms of both charge transport (electron/hole diffusion lengths of ca. 1 mm and 1.2 um, respectively, for CH3NH3PbI3� xClx), (3) and light absorption (1.5 � 10 4 cm � 1 at 550 nm). (4) In general, perovskite solar cells