scholarly journals Montecarlo Simulation and HAXPES Analysis of Organosilane Segregation in Titania Xerogel Films; Towards a Generic Surface Chemofunctionalization Process

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 352-365
Author(s):  
Javier Mateo Moreno ◽  
Rodrigo Calvo Membibre ◽  
Sergio Pinilla Yanguas ◽  
Juan Rubio Zuazo ◽  
Miguel Manso Siván
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Segregation ◽  
Titanium Isopropoxide ◽  
Condensation Process ◽  
X Ray ◽  
Depth Profiles ◽  
Partial Charges ◽  
Xerogel Films ◽  
Non Destructive

The formation of xerogels implies a sequence of hydrolysis and condensation reactions, which are intricate to analyze in heteromolecular sols. We analyze by probabilistic Montecarlo methods the development of hybrid organosilane–titania xerogels and illustrate how partial charges of the reacting molecules can help estimating relative probabilities for the condensation of the molecules. Since the condensation rate of Ti alkoxides is much higher than the corresponding rate of Si alkoxides (especially if bearing a non-hydrolizable group), by imposing a fast condensation process in agreement with low pH kinetics, the process leads to a surface segregation of the organosilane. The simulation results are compared with results of characterization of thin condensates of two different organosilanes within a titanium–isopropoxide matrix. Non-destructive in-depth profiles were obtained by hard x-ray photoelectron spectroscopy, which can resolve through estimation of Si and specific moieties of the organosilane molecules the progress of the condensation. These results are relevant for the generalization of chemo-functionalization processes by kinetic demixing of organosilanes, which have myriad applications in biomedicine and biotechnology.

Surface Characterization of Clean Gd5Ge4(010)

2012 ◽  
Vol 1517 ◽  
Author(s):  
Chad D. Yuen ◽  
Gordon J. Miller ◽  
Patricia A. Thiel
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Surface Segregation ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Show Evidence ◽  
Bulk Structure

AbstractBased on X-ray photoelectron spectroscopy, Gd5Ge4(010) does not show evidence of surface segregation. Scanning tunneling microscopy reveals two types of terraces which alternate laterally on the surface. From the step heights, these two surface terminations are assigned as dense, Gd-pure layers in the bulk structure. There is evidence of reconstruction on one type of terrace.

Characterization of thin Chemical/Native Oxides on Si (100) by Auger and Angle-Resolved XPS

1993 ◽  
Vol 318 ◽  
Author(s):  
Eddie D. Pylant ◽  
Carolyn F. Hoener ◽  
Mark F. Arendt ◽  
Bob Witowski
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Depth Distribution ◽  
Oxidation States ◽  
State Distribution ◽  
X Ray ◽  
Depth Profiles ◽  
Native Oxides ◽  
Target Factor Analysis

ABSTRACTChemical/native oxides grown on Si(100) after several standard wet cleans are characterized by Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS), and Auger Electron Spectroscopy using sputter depth profiles. Target Factor Analysis (TFA) was used to separate the Si LVV Auger peak into three components identified by their lineshapes and positions as Si, SiO2, and SiOx- Auger depth profiles were used to quantify the thickness of the oxides, the depth distribution, and amount of SiOx in the interface region. ARXPS was used to study the chemical state distribution in the native oxides as a function of depth. The depth distribution function from the Auger data was converted to an angle-resolved format for direct comparison to the angle-resolved XPS data. With this comparison, the SiOx lineshape is correlated to a 3:1 mixture of Si 3+ and Si 2+ oxidation states.

Non-destructive depth profile evaluation of multi-layer thin film stack using simultaneous analysis of data from multiple X-ray photoelectron spectroscopy instruments

2022 ◽  
Author(s):  
Yutaka Hoshina ◽  
Kazuya Tokuda ◽  
Yoshihiro SAITO ◽  
Yugo Kubo ◽  
Junji Iihara
Keyword(s):  
Thin Film ◽  
Data Analysis ◽  
Depth Profile ◽  
Photoelectron Spectroscopy ◽  
Simultaneous Analysis ◽  
Analysis Tool ◽  
X Ray ◽  
Depth Profiles ◽  
Layer Thin Film ◽  
Non Destructive

Abstract Non-destructive depth profile evaluation of multi-layer thin film stacks using simultaneous analysis of angle-resolved x-ray photoelectron spectroscopy data from multiple instruments is demonstrated. The data analysis algorithm, called the maximum smoothness method, was originally designed to handle data from a single XPS instrument with a single x-ray energy; in this work, the algorithm is extended to provide a simultaneous analysis tool which can handle data from multiple instruments with multiple x-ray energies. The analysis provides depth profiles for multilayer stacks that cannot be obtained by conventional data analysis methods. In this paper, metal multi-layer stack samples with total thickness greater than 10 nm are analyzed with the maximum smoothness method to nondestructively obtain depth profiles, with precise information on the chemical states of atoms in the surface layer (< 2 nm) and the overall layer stack structure, which can only be obtained by analyzing the data from multiple instruments.

The Growth and Characterization of Germanium-Carbon Alloy Thin Films

1992 ◽  
Vol 270 ◽  
Author(s):  
Haojie Yuan ◽  
R. Stanley Williams
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Vacuum Chamber ◽  
Optical Band Gap ◽  
High Vacuum ◽  
Optical Absorption Spectroscopy ◽  
Alloy Thin Film ◽  
New Materials ◽  
X Ray

ABSTRACTThin films of pure germanium-carbon alloys (GexC1−x with x ≈ 0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) have been grown on Si(100) and A12O3 (0001) substrates by pulsed laser ablation in a high vacuum chamber. The films were analyzed by x-ray θ-2θ diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), conductivity measurements and optical absorption spectroscopy. The analyses of these new materials showed that films of all compositions were amorphous, free of contamination and uniform in composition. By changing the film composition, the optical band gap of these semiconducting films was varied from 0.00eV to 0.85eV for x = 0.0 to 1.0 respectively. According to the AES results, the carbon atoms in the Ge-C alloy thin film samples has a bonding configuration that is a mixture of sp2 and sp3 hybridizations.

Monitoring and characterization of creation of geopolymers prepared from fly ash and metakaolin by X-ray photoelectron spectroscopy method

2014 ◽  
Vol 34 (3) ◽  
pp. 841-849 ◽  
Author(s):  
M. Kanuchova ◽  
L. Kozakova ◽  
M. Drabova ◽  
M. Sisol ◽  
A. Estokova ◽  
...  
Keyword(s):  
Fly Ash ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Method ◽  
X Ray

Characterization of columns grown during KrF laser micromachining of Al2O3–TiC ceramics

2003 ◽  
Vol 18 (5) ◽  
pp. 1123-1130 ◽  
Author(s):  
V. Oliveira ◽  
R. Vilar
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Laser Pulses ◽  
Formation Mechanisms ◽  
X Ray ◽  
Reducing Conditions ◽  
Transmission Electron ◽  
Column Formation ◽  
Krf Laser

This paper aims to contribute to the understanding of column formation mechanisms in Al2O3–TiC ceramics micromachined using excimer lasers. Chemical and structural characterization of columns grown in Al2O3–TiC composite processed with 200 KrF laser pulses at 10 J/cm2 was carried out by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction analysis. Fully developed columns consist of a core of unprocessed material surrounded by an outer layer of Al2TiO5, formed in oxidizing conditions, and an inner layer, formed in reducing conditions, composed of TiC and Al3Ti or an AlTi solid solution. Possible mechanisms of column formation are discussed.

Preparation of Carbon Nanofibers from Polyacrylonitrile Nanofibers by Electrospinning

2011 ◽  
Vol 415-417 ◽  
pp. 642-647
Author(s):  
En Zhong Li ◽  
Da Xiang Yang ◽  
Wei Ling Guo ◽  
Hai Dou Wang ◽  
Bin Shi Xu
Keyword(s):  
Electron Microscope ◽  
Carbon Nanofibers ◽  
Photoelectron Spectroscopy ◽  
Solution Concentration ◽  
Dimethyl Formamide ◽  
Ultrafine Fibers ◽  
X Ray ◽  
Scanning Electron ◽  
Pan Fibers

Ultrafine fibers were electrospun from polyacrylonitrile (PAN)/N,N-dimethyl formamide (DMF) solution as a precursor of carbon nanofibers. The effects of solution concentration, applied voltage and flow rate on preparation and morphologies of electrospun PAN fibers were investigated. Morphologies of the green fibers, stabilized fibers and carbonized fibers were compared by scanning electron microscope (SEM). The diameter of PAN nanofibers is about 450nm and the distribution of diameter is well-proportioned. Characterization of the elements changes of fibers were performed by X-ray photoelectron spectroscopy (XPS).

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