Search

Fundamental chemistry in heterogeneous catalysis is increasingly explored using operando techniques in order to address the pressure gap between ultrahigh vacuum studies and practical operating pressures. Because most operando experiments focus on the surface and surface-bound species, there is a knowledge gap of the near-surface gas phase and the fundamental information the properties of this region convey about catalytic mechanisms. We demonstrate in situ visualization and measurement of gas-phase species and temperature distributions in operando catalysis experiments using complementary near-surface optical and mass spectrometry techniques. The partial oxidation of methanol over a silver catalyst demonstrates the value of these diagnostic techniques at 600 Torr (800 mbar) pressure and temperatures from 150 to 410 °C. Planar laser-induced fluorescence provides two-dimensional images of the formaldehyde product distribution that show the development of the boundary layer above the catalyst under different flow conditions. Raman scattering imaging provides measurements of a wide range of major species, such as methanol, oxygen, nitrogen, formaldehyde, and water vapor. Near-surface molecular beam mass spectrometry enables simultaneous detection of all species using a gas sampling probe. Detection of gas-phase free radicals, such as CH3 and CH3O, and of minor products, such as acetaldehyde, dimethyl ether, and methyl formate, provides insights into catalytic mechanisms of the partial oxidation of methanol. The combination of these techniques provides a detailed picture of the coupling between the gas phase and surface in heterogeneous catalysis and enables parametric studies under different operating conditions, which will enhance our ability to constrain microkinetic models of heterogeneous catalysis. (Less)

Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key characteristic for high-quality hydrocarbon reservoirs. A standard procedure within Improved Oil Recovery (IOR) is seawater-injection which repressurizes the reservoir pore pressure. Long-term seawater-injection will influence mineralogical processes as dissolution and precipitation of secondary minerals. These secondary minerals (

International audience; Alsingle bondSi coated boron steels have been of interest for many years because of their superior mechanical properties and their excellent oxidation resistance. These high strength steels are particularly used in hot stamping processes during which the Alsingle bondSi coating undergoes multiple microstructural transformations. In this study, morphology and structure transformations are investigated using an original approach. Most of the time, the coating evolution is studied in cross section, by ex situ characterization of its different layers after heat treatment. In this work, the evolution of the surface is explored for the first time using in situ high-temperature Environmental Scanning Electron Microscopy (HT-ESEM). The austenitization step reproduced in the ESEM chamber allows a precise description of several surface changes occurring, depending on the temperature range. Among them, the main change in morphology is occurring between 650 and 800 °C and is linked to different reactions between aluminium and bi- and ternary Fe-Al-Si phases. The heating rate is also pointed out as a key parameter that affects the surface morphology. In fact, with low heating rates the surface is mostly composed of hexagonal and rectangular elements coming from τ5 (Fe2Al8Si) structuration, while needle-shaped FeAl3 structures are found for higher heating rates. In addition, it is observed that the heating rate also affects the surface roughness depending on the surface morphology. Finally, the origin of the presence of micrometrics pores appearing between 800 and 900 °C at the coating surface is discussed. Our hypothesis supported by ex situ characterization is that they result from formation of a crystallized oxide layer, probably close to α-Al2O3 structure.

Exquisite control of the electrodeposition of metal films and coatings is critical to a number of high technology and manufacturing industries, delivering functionality as\ud diverse as anti-corrosion and anti-wear coatings, electronic device interconnects and energy storage. The frequent involvement of more than one metal motivates the\ud capability to control, maintain and monitor spatial disposition of the component metals, whether as multilayers, alloys or composites. Here we investigate the deposition, evolution and dissolution of single and two-component metal layers involving Ag, Cu, and Sn on Au substrates immersed in the deep eutectic solvent (DES) Ethaline. During galvanostatically controlled stripping of the metals from two-component systems the potential signature in simultaneous thickness electrochemical potential (STEP) measurements provides identification of the dissolving metal; coulometric assay of deposition efficiency is an additional outcome. When combined with quartz crystal microbalance (QCM) frequency responses, the mass change : charge ratio provides oxidation state data; this is significant for Cu in the high chloride environment provided by Ethaline. The spatial distribution (solvent penetration and external roughness) of multiple components in bilayer systems is provided by specular neutron reflectivity (NR). Significantly, the use of the recently established event mode capability shortens the\ud observational timescale of the NR measurements by an order of magnitude, permitting dynamic in situ observations on practically useful timescales. Ag,Cu bilayers of both\ud spatial configurations give identical STEP signatures indicating that, despite theextremely low layer porosity, thermodynamic constraints (rather than spatial accessibility) dictate reactivity; thus, surprisingly, Cu dissolves first in both instances. Sn penetrates the Au electrode on the timescale of deposition; this can be prevented by interposing a layer of either Ag or Cu.

Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. Here, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inlet providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. The results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.

Naturally occurring pradimicins (PRMs) show specific recognition of d-mannose (d-Man) in aqueous media, which has never been achieved by artificial small molecules. Although the Ca2+-mediated dimerization of PRMs is essential for their d-Man binding, the dimeric structure has yet to be elucidated, leaving the question open as to how PRMs recognize d-Man. Thus, we herein report the structural elucidation of the dimer by a combination of X-ray crystallography and solid-state NMR spectroscopy. Coupled with our previous knowledge regarding the d-Man binding geometry of PRMs, elucidation of the dimer allowed reliable estimation of the mode of d-Man binding. Based on the binding model, we further developed an azide-functionalized PRM derivative (PRM-Azide) with d-Man binding specificity. Notably, PRM-Azide stained Candida rugosa cells having mannans on their cell surface through conjugation with the tetramethylrhodamine fluorophore. The present study provides the practical demonstration that PRMs can serve as lectin mimics for use in glycobiological studies., ファイル公開：2020-07-18

Lithium ions in LiMn2O4 crystals have been shown observable by using an aberration corrected electron microscope (R005) which has achieved a sub-50 pm resolution. Based on the annular bright-field image of the observed image, surface imaging of a LiMn2O4 crystal is discussed through simulation. The present simulation showed that ABF images with large convergence angles are sensitive to the top surface profile. A vacancy locating at the top surface of the lithium or manganese atomic columns can be observable with contrast reduced by 10-25% from the columns without vacancy. [DOI: 10.1380/ejssnt.2012.454]

Surface metallization by plasma coating enhances desorption/ionization of membrane components such as lipids and sterols in imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) of tissues and cells. High-resolution images of cholesterol and other membrane components were obtained for neuroblastoma cells and revealed subcellular details (resolving power 1.5 mum). Alternatively, in matrix-enhanced SIMS, 2,5-dihydroxybenzoic acid electrosprayed on neuroblastoma cells allowed intact molecular ion imaging of phosphatidylcholine and sphingomyelin at the cellular level. Gold deposition on top of matrix-coated rat brain tissue sections strongly enhanced image quality and signal intensity in stigmatic matrix-assisted laser desorption/ionization imaging mass spectrometry. High-quality total ion count images were acquired, and the neuropeptide vasopressin was localized in the rat brain tissue section at the hypothalamic area around the third ventricle. Although the mechanism of signal enhancement by gold deposition is under debate, the results we have obtained for cells and tissue sections illustrate the potential of this sample preparation technique for biomolecular surface imaging by mass spectrometry.

Application of atop-surface imaging(TSI) process by silylation to ArF lithography is desirable for ULSI production with minimum feature size for sub-120nm. We evaluated lithographic performances of non-chemically amplified positive TSI photoresist and chemically amplified negative TSI photoresist, both based on phenolic polymer. When off-axis illumination was used, 120nm and 110nm L/S patterns were obtained with non-chemically amplified resist(non-CAR) and chemically amplified resist(CAR) respectively. 100nm L/S patterns of CAR were obtained with strong off-axis illumination using binary intensity mask. CAR was superior to non-CAR in terms of lithographic performances, but inferior to non-CAR in terms of resist pattern collapse. Line edge roughness(LER) of CAR was sufficiently minimized by optimizing silylation bake temperature and it was comparable to that of single layer resist. For the prevention of resist pattern collapse in dry development process, the property of adhesion and resist rigidity is impor ant. This results can help the design of matrix resin of TSI resist for sub-100nm lithography.

Near-infrared (NIR) optical imaging is a noninvasive and nonionizing modality that is emerging as a diagnostic tool for breast cancer. The handheld optical devices developed to date using the NIR technology are predominantly developed for spectroscopic applications. A novel handheld probe-based optical imaging device has been recently developed toward area imaging and tomography applications. The three-dimensional (3D) tomographic imaging capabilities of the device have been demonstrated from previous fluorescence studies on tissue phantoms. In the current work, fluorescence imaging studies are performed on tissue phantoms, in vitro, and in vivo tissue models to demonstrate the fast two-dimensional (2D) surface imaging capabilities of this flexible handheld-based optical imaging device, toward clinical breast imaging studies. Preliminary experiments were performed using target(s) of varying volume (0.23 and 0.45 cm(3)) and depth (1-2 cm), using indocyanine green as the fluorescence contrast agent in liquid phantom, in vitro, and in vivo tissue models. The feasibility of fast 2D surface imaging ( approximately 5 seconds) over large surface areas of 36 cm(2) was demonstrated from various tissue models. The surface images could differentiate the target(s) from the background, allowing a rough estimate of the target's location before extensive 3D tomographic analysis (future studies).

The surface imaging processes using germylating agents are investigated. The removability of the resist is expected to be improved by using germylation instead of silylation. The reactivity of several germylating agents with phenolic OH group is evaluated. And germylamine compounds are found to exhibit the highest reactivity among them. Three different types of surface imaging processes are demonstrated and submicron patterns are obtained with each process. Bis(triethylgermyl)amine (BGA) as the germylating agent and PLASMASK 200G-C are used for these processes. The reactivity of BGA is higher than that of HMDS.In the deep UV exposure process, the differences between the germylation and the silylation are investigated on the oxygen dry etching characteristics and the diffusion depth of the reaction. The process using the germylation by BGA is found to have higher oxygen dry etching resistance and lower swelling which corresponds to the diffusion depth in germylated area as compared with the silylation by HMDS. From these results the surface imaging process is expected to have high controllability for linewidth by using the germylation.

Poly(p-vinylbenzoic acid) and its ester are opaque below 300nm and therefore useful in deep UV top surface imaging (TSI), which is a viable technique to overcome the shallow depth of focus and topography effects. In this paper are described two TSI systems utilizing the benzoic acid derivatives in the chemical amplification scheme. The first system is a single-layer negative TSI based on gas-phase silylation of poly(t-butyl p-vinylbenzoate) resist. The second case is the use of poly(p-vinylbenzoic acid) as a strippable bottom layer in conjunction with a thermally-developable, oxygen RIE barrier resist, which comprises an all-dry bilayer, positive TSI system.

A novel design concept for the electron optical column has been implemented in the realization of a new ultra-high performance SEM. A compound magnetic/ electrostatic objective lens is at the heart of the high-performance column: the imaging aberrations of this new lens type decrease with decreasing beam energy. Any beam cross-over between the electron source (Schottky FE-gun) and the sample has been eliminated in order to avoid broadening of the beam energy spread (Boersch effect). A high beam energy is maintained throughout the column regardless of the electron probe energy selected by the operator. This protects the beam against the effect of stray fields and minimizes any loss of beam brigthness due to stochastic electron-electron interactions. The new SEM achieves outstanding resolution, particularly at the low beam energies (3 nm achievable at E(PE) = 1 keV). The secondary electrons emitted by the sample are detected with very high efficiency by an internal annular detector situated above the final lens. Due to the low imaging aberration level, a high current can easily be focused in a very small probe, thus making the new SEM ideally suited for high-resolution, quantitative X-ray analysis.

The atomic force microscope was introduced in 198A as a new instrument lor examining the surface of insulating crystals. There was a clear implication in the first paper that it was capable of resolving single atoms. Unambiguous evidence for atomic resolution with the AFM did not appear until 1993. In the intervening years the AFM evolved into a mature instrument that provides us with new insights in the fields of surface science, electrochemistry, biology and the technology. In this paper we will discuss the evolution of this new high resolution microscope and describe some of the events that led up to the present state-of-the-art instrument.

In this paper, liquid-phase silylation process for Top Surface Imaging Lithography systems incorporating e-beam exposure has been experimentally investigated using FT-IR spectroscopy, UV spectroscopy, SIM spectrometry and SEM cross-sectionals. The impact of different silylating agents on Shipley SPR505A resist system is presented for both the UV exposed and e-beam crosslinked regions of the resist. Results show that an e-beam dose of 50/spl mu/C/cm/sup 2/ at 30keV is sufficient to crosslink the resist and prevent silylation. The silylation contrast using HMCTS was found to be the highest (11:1) in comparison with other two agents. It was found that the silicon incorporation in SPR505A resist follows Case II diffusion mechanisms.

This article focuses on the technical issues of imaging of dynamic adsorbate pattern formation on platinum surfaces using laser light to illuminate the area of interest. In particular, ellipsomicroscopy for surface imaging (EMSI) is a powerful tool to follow spatio-temporal patterns of adsorbate layers on catalyst surfaces at arbitrary pressures. This novel method is uniquely sensitive to submonolayer coverages of adsorbates. It expands the range of observable pressure conditions by many orders of magnitude, thus bridging the pressure gap in imaging surface reactions. EMSI is a versatile technique that opens new avenues of potential applications to resolve dynamic surface processes, such as adsorbate diffusion or coating formation.

Optical imaging of fluorescent objects embedded in a tissue simulating medium was characterized using non-contact based approaches to fluorescence remittance imaging (FRI) and sub-surface fluorescence diffuse optical tomography (FDOT). Using Protoporphyrin IX as a fluorescent agent, experiments were performed on tissue phantoms comprised of typical in-vivo tumor to normal tissue contrast ratios, ranging from 3.5:1 up to 10:1. It was found that tomographic imaging was able to recover interior inclusions with high contrast relative to the background; however, simple planar fluorescence imaging provided a superior contrast to noise ratio. Overall, FRI performed optimally when the object was located on or close to the surface and, perhaps most importantly, FDOT was able to recover specific depth information about the location of embedded regions. The results indicate that an optimal system for localizing embedded fluorescent regions should combine fluorescence reflectance imaging for high sensitivity and sub-surface tomography for depth detection, thereby allowing more accurate localization in all three directions within the tissue.

Reflection ion microscopy (RIM) is a technique that uses a low angle of incidence and scattered ions to form an image of the specimen surface. This paper reports on the development of the instrumentation and the analysis of the capabilities and limitations of the scanning RIM in a helium ion microscope (HIM). The reflected ions were detected by their “conversion” to secondary electrons on a platinum surface. An angle of incidence in the range 5–10° was used in the experimental setup. It was shown that the RIM image contrast was determined mostly by surface morphology but not by the atomic composition. A simple geometrical analysis of the reflection process was performed together with a Monte Carlo simulation of the angular dependence of the reflected ion yield. An interpretation of the RIM image formation and a quantification of the height of the surface steps were performed. The minimum detectable step height was found to be approximately 5 nm. RIM imaging of an insulator surface without the need for charge compensation was successfully demonstrated.

Group III−V nanowires offer the exciting possibility of epitaxial growth on a wide variety of substrates, most importantly silicon. To ensure compatibility with Si technology, catalyst-free growth schemes are of particular relevance, to avoid impurities from the catalysts. While this type of growth is well-documented and some aspects are described, no detailed understanding of the nucleation and the growth mechanism has been developed. By combining a series of growth experiments using metal−organic vapor phase epitaxy, as well as detailed in situ surface imaging and spectroscopy, we gain deeper insight into nucleation and growth of self-seeded III−V nanowires. By this mechanism most work available in literature concerning this field can be described.

The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (10(15)-10(19) atoms cm(-3)) and covered with dielectric thin films of SiO2 (100-400 nm thickness) are measured to demonstrate the sensitivity of scanning microwave microscopy (SMM) for sub-surface imaging. Using standard SMM imaging conditions the dopant areas could still be sensed under a 400 nm thick oxide layer. Non-contact SMM imaging in lift-mode and constant height mode is quantitatively demonstrated on a 50 nm thick SiO2 test pad. The differences between non-contact and contact mode capacitances are studied with respect to the main parameters influencing the imaging contrast, namely the probe tip diameter and the tip-sample distance. Finite element modelling was used to further analyse the influence of the tip radius and the tip-sample distance on the SMM sensitivity. The understanding of how the two key parameters determine the SMM sensitivity and quantitative capacitances represents an important step towards its routine application for non-contact and sub-surface imaging.

International audience; Photoelectron emission microscopy (PEEM) is a powerful non-destructive tool for spatially resolved, spectroscopic analysis of surfaces with sub-micron chemical heterogeneities. However, in the case of micron scale patterned semiconductors, band line-ups at pn junctions have a built-in lateral electric field which can significantly alter the PEEM image of the structure with respect to its physical dimensions. Furthermore, real surfaces may also have physical topography which can reinforce or counteract the electrically induced distortion at a pn junction. We have measured the experimental PEEM image distortion at such a junction and carried out numerical simulations of the PEEM images. The simulations include energy filtering and the use of a contrast aperture in the back focal plane in order to describe the changes in the PEEM image of the junction with respect to its real physical dimensions. Threshold imaging does not give a reliable measurement of micron sized p and n type patterns. At higher take-off energies, for example using Si 2p electrons, the pattern width is closer to the real physical size. Physical topography must also be quantitatively accounted for. The results can be generalized to PEEM imaging of any structure with a built-in lateral electric field.

We measured the fully resolved 3-dimensional velocity distributions of nitric oxide photodesorbed from a gold single crystal. These experiments combine time-of-flight measurements and the velocity map imaging technique to yield velocity distributions resolved in three dimensions for a prototypical surface-adsorbate system. Nitric oxide adsorbed on Au(100) was photodesorbed using a 355 nm laser beam. The desorbed NO molecules were ionised in the gas-phase by resonance-enhanced multi-photon ionisation within a set of velocity map imaging optics. The NO molecules preferentially leave the surface along the surface normal with a very narrow angular distribution, indicating a non-thermal desorption process.

As a model surface, graphite slides were treated by pure nitrogen gas plasma for different periods (15 sec - 5 min). These samples were kept in air or under argon atmosphere in sealed holders. STM images were obtained at constant current mode. Results showed that both the number and the size of clusters formed by plasma deposition increased with exposure time.As a model surface, graphite slides were treated by pure nitrogen gas plasma for different periods (15 sec- 5 min). These samples were kept in air or under argon atmosphere in sealed holders. STM images were obtained at constant current mode. Result showed that both the number and the size of clusters formed by plasma deposition increased with exposure time.

BACKGROUND: In vivo reflectance confocal microscopy (RCM) is well established in non-melanoma skin cancer detection and screening. However, there is no sufficient validation regarding intraoperatively obtained images of wound margins. A reliable and fast resection margin detection is of high clinical relevance. Hence, we aimed to investigate feasibility and validity of in vivo RCM imaging for wound margins assessment compared with standard skin surface imaging and the gold standard histopathology. METHODS: A surgical incision through the center of a large basal cell carcinoma (BCC) affected area in the head and face region was performed. After removing half of the tumor, the wound margins of the remaining half as well as the corresponding skin surface were scanned with an in vivo RCM. A total of 50 wound margin images with BCC, 50 images of BCC-free margins and the corresponding skin surface images from 50 patients were compared with each other and with histopathological findings. Presence of confocal diagnostic criteria for BCC in images was analyzed. RESULTS: An overall sensitivity and specificity in detection of BCC in wound margins was 88.5%, and 91.7% compared to skin surface imaging and 97.8% and 90.7%, respectively, compared to histopathology. We identified all known confocal patterns of healthy skin and BCC in wound margin scans: damage of the epidermal layer above the lesion and cellular pleomorphism, elongated and monomorphic basaloid nuclei, nuclear polarization, an increased number of dilated blood vessels with high leukocyte traffic, inflammatory cells. CONCLUSIONS: The accuracy of in vivo RCM imaging of wound margins is comparable with a standard skin surface imaging. The intraoperative detection of BCC areas in wound margins is as precise as the standard skin imaging and may be supportive for surgical interventions.

Herein, we report knitting of a thiophenyltriazine-based porous organic polymer (TTPOP) with high surface area and high abundance of nitrogen and sulfur sites, synthesized through a simple one-step Friedel–Crafts reaction of 2,4,6-tri(thiophen-2-yl)-1,3,5-triazine and formaldehyde dimethyl acetal in the presence of anhydrous FeCl3, and thereafter grafting of Cu(OAc)2·H2O in the porous polymer framework to achieve the potential catalyst (CuII-TTPOP). TTPOP and CuII-TTPOP were characterized thoroughly utilizing solid-state 13C-CP MAS NMR, Fourier transform infrared, wide-angle powder X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy and surface imaging by transmission electron microscopy and field emission scanning electron microscopy. The porosity of the nanomaterials was observed in the surface imaging and verified through conducting N2 gas adsorption techniques. Keeping in mind the tremendous importance of C-C and C-N coupling and cyclization processes, the newly synthesized CuII-TTPOP was employed successfully for a wide range of organic catalytic transformations under mild conditions to afford directly valuable diindolylmethanes and spiro-analogues, phthalimidines, propargyl amines, and their sugar-based chiral compounds with high yields using readily available substrates. The highly stable new heterogeneous catalyst showed outstanding sustainability, robustness, simple separation, and recyclability.

The performance of mercury cadmium telluride (MCT)-based infrared (IR) focal-plane arrays is closely related to the crystalline perfection of the HgCdTe thin film. In this work, Te-rich, (111)B-oriented HgCdTe epilayers grown by liquid-phase epitaxy on CdZnTe substrates have been studied. Surface atomic steps are shown on as-grown MCT materials using atomic force microscopy (AFM) and white-light interferometry (WLI), suggesting step-flow growth. Locally, quasiperfect surface spirals are also evidenced. A demonstration is given that these spirals are related to the emergence of almost pure screw threading dislocations. A nondestructive and quantitative technique to measure the threading dislocation density is proposed. The technique consists of counting the surface spirals on the as-grown MCT surface from images obtained by either AFM or WLI measurements. The benefits and drawbacks of both destructive—chemical etching of HgCdTe dislocations—and nondestructive surface imaging techniques are compared. The nature of defects is also discussed. Finally, state-of-the-art threading dislocation densities in the low 104 cm−2 range are evidenced by both etch pit density (EPD) and surface imaging measurements.

Graphical abstract, Highlights • Electromechanical properties of metal films are studied with in-situ AFM-4PP tensile straining. • AFM characterizes the surface damage and 4PP measures the resistance under tensile strain. • The difference between local film necking and through thickness cracks can be made. • It will be shown when the strain is removed, cracks bridge and the resistance decreases., In order to advance flexible electronic technologies it is important to study the electrical properties of thin metal films on polymer substrates under mechanical load. At the same time, the observation of film deformation and fracture as well as the stresses that are present in the films during straining are also crucial to investigate. To address both the electromechanical and deformation behavior of metal films supported by polymer substrates, in-situ 4 point probe resistance measurements were performed with in-situ atomic force microscopy imaging of the film surface during straining. The 4 point probe resistance measurements allow for the examination of the changes in resistance with strain, while the surface imaging permits the visualization of localized thinning and crack formation. Furthermore, in-situ synchrotron tensile tests provide information about the stresses in the film and show the yield stress where the deformation initiates and the relaxation of the film during imaging. A thin 200 nm Cu film on 23 μm thick PET substrate will be used to illustrate the combined techniques. The combination of electrical measurements, surface imaging, and stress measurements allow for a better understanding of electromechanical behavior needed for the improvement and future success of flexible electronic devices.

When ductile metal films on compliant polymer substrates are strained in tension catastrophic failure can be suppressed by the substrate, thus allowing for their use in flexible electronics and sensors. However, the charge carrying ductile films must be of an optimum thickness and microstructure for the suppression of cracking to occur. Studies of strained films on polymer substrates tend to have more emphasis on the electrical properties and thickness effects than on the film microstructure or deformation behaviour. To address both the electrical degradation and deformation behaviour of metal films supported by polymer substrates two types of combined electro-mechanical in-situ tests were performed. First, is a combination of in-situ resistance measurements with in-situ confocal scanning laser microscopy imaging of the film surface during cycling. The 4 point probe resistance measurements allow for the examination of the changes in resistance with strain, while the surface imaging permits the visualization of extrusion and crack formation. Second, is the combination of in-situ resistance with in-situ X-ray diffraction measurements of the film stresses during cycling. The combination of electrical measurements, surface imaging, and stress measurements allow for a complete picture of electro-mechanical behaviour needed for the improvement and future success of flexible electronic devices.

To improve Organic Thin Film Transistor (OTFT) properties we study OTFT semiconductor/dielectric interfacial properties via examination of the gate dielectric using thin Parylene C layer. Structural and morphology properties of pentacene layers deposited on parylene layer and SiO2/Si substrate structure were compared. The surface morphology was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM topography of pentacene layer in non-contact mode confirmed the preferable pentacene grain formation on parylene surface in dependence on layer thickness. The distribution of chemical species on the surfaces and composition depth profiles were measured by secondary ion mass spectroscopy (SIMS) and surface imaging. The depth profiles of the analyzed structures show a homogenous pentacene layer, characterized with C or C2 ions. Relatively sharp interface between pentacene and parylene layers was estimated by characteristic increased intensity of CCl ions peak. For revealing the pentacene phases in the structures the Micro-Raman spectroscopy was utilized. Conformal coatings of parylene and pentacene layers without pinholes resulted from the deposition process as was confirmed by SIMS surface imaging. For the pentacene layers thicker than 20 nm, both thin and bulk pentacene phases were detected by Micro-Raman spectroscopy, while for the pentacene layer thickness of 5 and 10 nm the preferable thin phase was detected. The complete characterisation of pentacene layers deposited on SiO2 and parylene surface revealed that the formation of large grains suggests 3D pentacene growth at parylene layer with small voids between grains and more than one monolayer step growth. The results will be utilized for optimization of the deposition process.

My thesis work focuses on the integration of scanning tunneling microscopy with infrared spectroscopy, to provide unprecedented �-scale resolution in surface imaging with spatially correlated chemical specificity. Scanning probe techniques generally lack chemical information. Inspired by recent advances coupling optical spectroscopies with scanning probe microscopies, I have developed a nanoscale infrared spectroscopic imaging method applying scanning tunneling microscope probe tips as nanoamplifiers to obtain multiplexed molecular vibrational signals utilizing a Fourier transform interferometer at room temperature and ambient pressure. The sensitivity of the tunneling junction and nanoscale probe area enables the measurement of vibrational spectra orders of magnitude below the diffraction limit. I substantiated the effectiveness of this instrument by designing an air- and temperature-stable model system characterized by infrared absorption that couples to the electronic states of the gold substrate. Specifically, aurous cyanide (AuCN) self-assembled monolayers satisfy these requirements with the added benefit that its IR absorption lies outside of the carbon dioxide and water windows, thereby maintaining high signal-to-noise ratios for these experiments. These atomically pristine hexagonal close-packed AuCN monolayers exhibit a strong absorption at 2140 cm−1. Upon thermal annealing, the surface rearranges into a ribbon structure with a blue-shifted absorption to 2230 cm−1. The unique vibrational contrast in AuCN monolayers resulting from thermally induced structural changes serves as an ideal model system for the new infrared scanning tunneling microscope (IR-STM). Upon prolonged vapor deposition, the self-assembled cyanide monolayers reconfigure into large-scale AuCN crystals, giving two distinct morphologies and significantly different vibrational modes, compared to the AuCN monolayer structures. Once again, temperature can tune gold-cyanide orientation and long-range ordering. This work provides new insights for controlled surface-mediated crystal growth in AuCN systems. Ultimately, combining with the chemical information gained from the developed IR-STM, surface-mediated growth will enable new methodologies for fabricating next-generation nanoscale semiconductors. Nanoscale semiconductors based on AuCN that are similar to nanoribbon structures have been demonstrated to be useful for nanoelectronics as well as in catalytic applications.

X-ray-induced ablation of Si-containing polymers is investigated for application to the surface-imaging process in X-ray lithography. Polysilanes, polystyrene, and polymethacrylates are chosen for this study. Ultraviolet (UV) and Fourier-transfer infrared (FTIR) spectra are observed and all of the polymers are found to have positive tone characteristics against soft X-ray exposure. Based on measurements of remaining film thickness after exposure, polymethacrylates are found to have a high self development sensitivity. However, copolymerization gives no improvement in sensitivity. Oxygen reactive ion etching (O2-RIE) rates of these polymers are also measured and found to depend on the Si content of the polymer. A bilayer resist using the polymer as a surface imaging resist is patterned by X-ray exposure and subsequent dry etching. Applicability of Si-containing X-ray resist to self-development is presented.

Carbon nanospheres (CNS) have tremendous potential in photocatalysis due to their unique opto-electronic properties that facilitated effective electron transfer and high visible-light harvesting nature. The present work deals with the design and synthesis of novel ternary hierarchical SrTiO3/CdS/carbon nanospheres photocatalytic system and evaluated its photocatalytic performance for H2 production under sunlight illumination. The ternary photocatalytic system formation is explained using surface imaging (FE-SEM and TEM) and surface chemical analysis (XPS). At optimized conditions, the ternary SrTiO3/CdS/carbon nanospheres’ photocatalytic system has exhibited excellent H2 production of 3085 μmol h−1 gcat−1 when compared to single and binary photocatalytic systems. The incorporation of carbon nanospheres takes part as an electron nabber and carrier to improve the electron transfer of the SrTiO3/CdS photocatalytic system in the hierarchical ternary photocatalytic system. The high H2 production of the ternary SrTiO3/CdS/carbon nanospheres’ photocatalytic system is demonstrated by photocurrent and lifetime PL studies. Furthermore, a suitable mechanism is also proposed.

Live imaging of Xenopus embryos and organotypic explants can be challenging because of their large size and slippery nature. This protocol covers the preparation of special chambers for immobilizing Xenopus embryos and embryonic explants for live-cell and tissue imaging. The opaque nature of Xenopus embryonic tissues enables simple bright-field imaging techniques for tracking surface movements across large regions. Such surface imaging of embryos or organotypic explants can directly reveal cell behaviors, obviating the need for complex postprocessing commonly required to extract this data from 3D confocal or light-sheet observations of more transparent embryos. Furthermore, Xenopus embryos may be filled with light-absorbing pigment granules and light-scattering yolk platelets, but these limitations are offset by the utilitarian nature of Xenopus organotypic explants that expose and stabilize large embryonic cells in a nearly native context for high-resolution live-cell imaging. Additionally, whole embryos can be stabilized for long-term bright-field and confocal microscopy. Simple explants can be prepared using a single cell type, and organotypic explants can be prepared in which multiple tissue types are dissected while retaining native tissue–tissue interactions. These preparations enable both in-toto imaging of tissue dynamics and super-resolution imaging of protein dynamics within individual cells. We present detailed protocols for these methods together with references to applications.

With the increasing demands for energy utilization and storage, the secondary lithium batteries with high energy-density and high safety performance are being continuously developed and improved. An in-depth understanding of the electrochemical process and corresponding micro-mechanism at the electrode/electrolyte interface of lithium batteries during charging and discharging is beneficial to open new avenues of guiding the optimal design of battery materials. In situ electrochemical atomic force microscopy (AFM) combines high-resolution surface-imaging of AFM with electrochemical characterizations, unraveling the direct visualization and dynamic evolution of the electrode/electrolyte interface in a working battery at nanoscale. This article reviews the latest research progress of in situ electrochemical AFM investigations into the electrode processes of lithium batteries, including the interfacial reaction process of the conversion-type cathode, the dynamic evolution of the solid electrolyte interphase film at the electrode/electrolyte interface, and the structural evolution in solid-state lithium batteries.

Agglomeration in solid composite propellants is known to exacerbate two-phase flow losses. In this experimental study, we investigate the substitution of aluminum particles with metallic alloys in order to reduce agglomeration in aluminized propellants. We consider five different aluminum-based alloys: Al-Mg, Al-Ni, Al-Si, Al-B, and Al-Zn. Through thermogravimetric-differential scanning calorimetry measurements, we find that all five alloys can increase the initial oxidation temperature relative to a baseline Al propellant, but that only Al-Si and Al-Zn exhibit lower melting temperatures. Laser ignition experiments show that Al-Mg produces the most balanced combination of a short ignition delay time and a short self-sustaining combustion time. High-pressure experiments at 0.5 to 3 MPa show that Al-Si has a markedly higher burning rate than the baseline Al propellant, while Al-Mg and Al-Ni have the lowest pressure exponents. High-speed microscopic surface imaging at 0.5 and 1 MPa shows that Al-Ni produces the largest reduction in agglomeration, with an average agglomerate size some 30% smaller than the baseline value. By contrast, Al-Zn produces the worst agglomeration, with an average agglomerate size around 15% larger than the baseline value. From these findings, we propose a qualitative phenomenological mechanism for agglomeration in metallic-alloy propellants based on a competition among four distinct effects: the metal melting temperature, the adhesive force of the agglomerates, the propellant burning rate, and micro-explosions. We then analyze the agglomeration of the different alloys using the proposed mechanism. As well as providing new experimental data on the agglomeration, ignition and combustion characteristics of solid composite propellants containing aluminum-based alloys, this study reinforces the notion that the agglomeration and combustion performance of aluminized propellants can be optimized through a judicious choice of alloying elements.