scholarly journals Photoelectron Spectroscopy using Pulsed Free Jets

1986 ◽  
Vol 39 (5) ◽  
pp. 789 ◽  
Author(s):  
Frank Carnovale ◽  
J Barrie Peel ◽  
Richard G Rothwell
Keyword(s):  
Band Structure ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Free Jets ◽  
Free Jet ◽  
Hot Band ◽  
The One ◽  
Ammonia Clusters

The use of pulsed gaseous free jets in the study of atomic and molecular species by ultraviolet photoelectron spectroscopy (UPS) offers a number of advantages over the usual continuous flow room temperature technique. Pulsed free jet expansions provide, on the one hand, 'cold' molecules for which spectroscopy is simplified through the absence of hot band structure and, on the other hand, cluster species including dimers, trimers and higher clusters, as well as intermolecular species, all generally of low intermolecular binding energies. Furthermore a high pressure gas pulse is a suitable medium for the preparation, relaxation and transport of reactive species formed in processes such as pyrolysis, photodissociation or electrical discharge. This paper describes the modifications made to an ultraviolet photoelectron spectrometer to allow measurements on pulsed free jet expansions. The important features of the modified instrument concern the control of the gas beam and the timing electronics for photoelectron detection. Examples of He I photoelectron spectra presented include (a) the demonstration of hot band structure in the room temperature UPS of ammonia, (b) the preparation of the dimer (NOh and higher clusters (NO) n of nitric oxide, (c) the UPS of sulfur dioxide clusters (S02) n' and (d) the UPS of ammonia clusters (NH 3) n'

scholarly journals Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 202
Author(s):  
Miranda Martinez ◽  
Anil R. Chourasia
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Increasing Trend ◽  
Substrate Temperatures ◽  
Beam Technique

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO2 upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

Theoretical core spectroscopy of molecules interacting with ice surfaces 

2021 ◽  
Author(s):  
Richard Asamoah Opoku
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Trace Gases ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Development Fund ◽  
Xps Spectra ◽  
The Core ◽  
Ice Surfaces

<p><strong>Céline TOUBIN</strong><strong><sup>2</sup></strong><strong> and </strong><strong>André Severo Pereira GOMES</strong><strong><sup> 3</sup></strong></p><p><sup>2,3</sup> Laboratoire de Physique des Lasers, des atomes et des Molécules, Université de Lille, Cité Scientifique, 59655 Villeneuve d’Ascq Cedex, France</p><p>E-mail : [email protected]<sup>2</sup> ; [email protected]<sup>3</sup></p><p>Ice plays an essential role as a catalyst for reactions between atmospheric trace gases. The uptake of trace gases to ice has been proposed to have a major impact on geochemical cycles, human health, and ozone depletion in the stratosphere [1]. X-ray photoelectron spectroscopy (XPS) [2], serves as a powerful technique to characterize the elemental composition of such interacting species due to its surface sensitivity. Given the existence of complex physico-chemical processes such as adsorption, desorption, and migration within ice matrix, it is important to establish a theoretical framework to determine the electronic properties of these species under different conditions such as temperature and concentration. The focus of this work is to construct an embedding methodology employing Density Functional (DFT) and Wave Function Theory (WFT) to model and interpret photoelectron spectra of adsorbed halogenated species on ice surfaces at the core level with the highest accuracy possible. </p><p>We make use of an embedding approach utilizing full quantum mechanics to divide the system into subunits that will be treated at different levels of theory [3].</p><p>The goal is to determine core electron binding energies and the associated chemical shifts for the adsorbed halogenated species such as molecular HCl and the dissociated form Cl- at the surface and within the uppermost bulk layer of the ice respectively [4]. The core energy shifts are compared to the data derived from the XPS spectra [4].</p><p>We show that the use of a fully quantum mechanical embedding method, to treat solute-solvent systems is computationally efficient, yet accurate enough to determine the electronic properties of the solute system (halide ion) as well as the long-range effects of the solvent environment (ice).</p><p>We acknowledge support by the French government through the Program “Investissement d'avenir” through the Labex CaPPA (contract ANR-11-LABX-0005-01) and I-SITE ULNE project OVERSEE (contract ANR-16-IDEX-0004), CPER CLIMIBIO (European Regional Development Fund, Hauts de France council, French Ministry of Higher Education and Research) and French national supercomputing facilities (grants DARI x2016081859 and A0050801859).</p><p> </p>

X-Ray photoelectron spectroscopy of monosubstituted perfluorobenzenes

1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Sophisticated Analysis ◽  
Charge Calculations

The gas phase X-ray photoelectron spectra, XPS, were observed for the series C6F5X (X = F, Cl, I, Br, H). Binding energies were determined from the spectra using the ESCAPLOT Program. Charge calculations were carried out using Equalization of Electronegativity, CNDO/2, and ACHARGE approaches on each molecule. The more sophisticated analysis leads to the following equation correlating the (C 1s) binding energies and the atomic charges qi[Formula: see text]

Electronic Structure of One-Dimensional Biradical Molecular Chain

2014 ◽  
Vol 1605 ◽  
Author(s):  
H. Koike ◽  
K. Ogawa ◽  
T. Kubo ◽  
K. Uchida ◽  
M. Chikamatsu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Photoelectron Spectroscopy ◽  
Organic Molecules ◽  
Molecular Chain ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Deposition Method ◽  
One Dimensional ◽  
The One

ABSTRACTWe investigated electronic structure of one-dimensional biradical molecular chain which is constructed by exploiting the covalency between organic molecules of a diphenyl derivative of s-indacenodiphenalene (Ph2-IDPL). To control the crystallinity, we used gas deposition method. Ultraviolet photoelectron spectroscopy (UPS) revealed developed band structure with wide dispersion of the one-dimensional biradical molecular chain.

Study of transition metal oxides by photoelectron spectroscopy

1979 ◽  
Vol 367 (1729) ◽  
pp. 239-252 ◽  
Keyword(s):  
Transition Metal Oxides ◽  
Photoelectron Spectroscopy ◽  
Metal Ion ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Final State ◽  
Metal Insulator ◽  
X Ray ◽  
Valence States ◽  
Related Series

Systematics in the X-ray photoelectron spectra (X. p. e. s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row transi­tion metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit inter­esting variations with the oxidation state of the metal or the nuclear charge The 3d binding energies of the monoxides show a proportionality to Goodenough’s ( R — R c ). Other aspects of interest in the study are the satellite structure and final state effects in the X. p. e. s. of the oxides, and identification of different valence states in oxides of the general formulae M n O 2 n -1 and M 3 O 4 . The nature of changes in the 3d bands of oxides under­-going metal-insulator transitions is also indicated.

Anion Photoelectron Spectroscopy and High Level Ab Initio Calculations of the Halide–Nitric Oxide Dimer Complexes

2018 ◽  
Vol 71 (4) ◽  
pp. 265 ◽  
Author(s):  
Kim M. L. Lapere ◽  
Allan J. McKinley ◽  
Duncan Wild
Keyword(s):  
Nitric Oxide ◽  
Photoelectron Spectroscopy ◽  
Experimental Studies ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Basis Set ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Anion Photoelectron Spectroscopy ◽  
High Level

Anion photoelectron spectra are presented for gas phase complexes formed between halide anions and nitric oxide, X−⋯NO where X− = Cl−, Br−, and I−. Electron binding energies are experimentally determined to be 3.82, 3.51, and 3.17 eV. Results from CCSD(T)/aug-cc-pVTZ calculations are presented for the anion species, whereby a single minimum of Cs symmetry is predicted. Binding energies (D0) of 15.3, 13.3, and 11.7 kJ mol−1 are predicted from complete basis set limit extrapolation, and are found to be in line with previous experimental studies.

Measurements of Chemical Shifts in the Photoelectron Spectra of Arsenic and Bromine Compounds

1971 ◽  
Vol 25 (1) ◽  
pp. 33-36 ◽  
Author(s):  
L. D. Hulett ◽  
T. A. Carlson
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Ionic Character ◽  
X Rays ◽  
Arsenic Pollution ◽  
Oxidation Number ◽  
Hartree Fock ◽  
D Orbitals

Chemical shifts in the binding energies of electrons in 3 d orbitals of bromine and arsenic have been measured by photoelectron spectroscopy, using soft x rays. The bromine salts studied were KBr, KBrO3, and KBrO4; the results are compared to corresponding chlorine and iodine salts studied by other workers. For a given increase in oxidation number, the shift (increase) in binding energy of bromine is intermediate to those for chlorine and iodine, chlorine shifts are higher, and iodine shifts are lower. This trend can be qualitatively explained by Hartree-Fock calculations of differences in binding energies for free halogen ions. Chemical shifts for arsenic can be correlated to variations in the effective charges on arsenic caused by different chemical environments. Calculations of the charge were made by considering the partial ionic character of bonds. A demonstration that photoelectron spectroscopy can be used in arsenic pollution problems has been made.

XPS Studies at the Interface of Ti/AIN Ceramic

1994 ◽  
Vol 357 ◽  
Author(s):  
Dian Hong Shen ◽  
Changlin Bao ◽  
Hua Lu ◽  
Zhangda Lin
Keyword(s):  
Lower Energy ◽  
Room Temperature ◽  
Binding Energies ◽  
Ceramic Substrate ◽  
Photoelectron Spectra ◽  
Oxygen Binding ◽  
Metallic Titanium ◽  
Alumina Layer ◽  
Hydrated Alumina ◽  
Two Peaks

AbstractThe photoelectron spectra for titanium deposition on a AIN ceramic substrate at room temperature have been measured. Before deposition, the binding energies of Ols and Al 2p show that the substrate contained oxygen as a major impurity and a top layer of degeneration was formed. After deposition of a small amount of titanium, it was found that the Nls separated into two peaks(396.5 eV and 402 eV) and Ti 2p corresponded to the oxide state. With an increase of titanium coverage, the Ti 2p peak shifted toward a lower energy. The peak at 402 eV dominated at a titanium coverage of 0.9 nm, showing the nitrogen-oxygen binding character. For a titanium coverage of 3.0 nm, a new peak at 406 eV was formed. These results suggest that during deposition of Ti onto the AIN substrate which has a top hydrated alumina layer, some of nitrogen atoms tend to be bound with oxygen and to form an interfacial oxynitride layer between the metallic titanium and substrate.

scholarly journals Enhancing electrical properties of carbon nanotubes thin films by silicon incorporation

2021 ◽  
Vol 1206 (1) ◽  
pp. 012028
Author(s):  
Sk Faruque Ahmed ◽  
Mohibul Khan ◽  
Nillohit Mukherjee
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Binding Energies ◽  
Xps Spectra ◽  
X Ray ◽  
Vapor Deposition Technique

Abstract Silicon incorporated carbon nanotube (Si-CNTs) thin films was prepared by radio frequency plasma enhanced chemical vapor deposition technique. Tetraethyl orthosilicate solution was used for incorporation of silicon in CNTs thin films. Energy dispersive X-ray analysis shows that the silicon atomic percentage was varied from 0 % to 6.1 %. The chemical binding energies of carbon and silicon were analyzed from X-ray photoelectron spectroscopy data. The various peaks at ~531 eV, ~ 285 eV, ~155 eV and ~104 eV was observed in the XPS spectra due to the oxygen, carbon and silicon respectively. Surface morphologies of Si-CNTs thin films have been analyzed by field emission scanning electron microscopy, which revels that the length of the silicon incorporated carbon nanotubes ~500 nm and corresponding diameter ~80 nm. The room temperature electrical conductivity was increased whereas the activation energy was decreased with the increase of atomic percentage of silicon in Si-CNTs thin films. The room temperature electrical conductivity was increased from 4.3 × 103 to 7.1 × 104 S cm−1 as the silicon atomic percentage in Si-CNTs thin films increases from 0 to 6.1 % respectively.

scholarly journals X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

2015 ◽  
Vol 6 ◽  
pp. 177-192 ◽  
Author(s):  
Toma Susi ◽  
Thomas Pichler ◽  
Paola Ayala
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Nanomaterials ◽  
Compositional Analysis ◽  
Binding Energies ◽  
Graphitic Carbon ◽  
Photoelectron Spectra ◽  
Intrinsic Properties ◽  
Important Work ◽  
X Ray ◽  
General Care

X-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS.

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