UV-photoelectron Spectroscopy of Unhindered Germylenes and Carbon-arsenic Multiple-bonded Species

2010 ◽  
Vol 63 (12) ◽  
pp. 1608 ◽  
Author(s):  
Anna Chrostowska ◽  
Alain Dargelos ◽  
Alain Graciaa
Keyword(s):  
Experimental Data ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Group Iv ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Fundamental Information ◽  
Structure And Bonding ◽  
Uv Photoelectron Spectroscopy ◽  
Established Technique

Ultraviolet photoelectron spectroscopy (UV-PES) is a well established technique that provides ionization energies of molecules in the gas phase. Flash vacuum thermolysis or vacuum gas-solid reactions coupled with UV-PES are especially suited for the generation and analysis of small amounts of short-lived species in real-time. These experimental data, supported by quantum chemical calculations for the consistency of the assignments of PES spectra, provide fundamental information about electronic structure and bonding that is obtained by no other technique. This paper aims to give some representative original examples chosen from Pau’s research group that illustrate the advantages and wide applicability of these techniques. These examples show the selected data and conclusions which focus on the reactivity of low-coordinated of Main Group IV and V elements. Germylenes and simplest carbon-arsenic multiple bonded species ware successfully characterized using UV photoelectron spectroscopy – a very powerful, direct characterization instrument.

Recent Studies on Flash Vacuum Thermolysis in Tandem with UV-Photoelectron Spectroscopy and Quantum Calculations

2014 ◽  
Vol 67 (9) ◽  
pp. 1166 ◽  
Author(s):  
Anna Chrostowska ◽  
Stanisław Leśniak
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Quantum Calculations ◽  
Fundamental Information ◽  
Spectroscopic Characterisation ◽  
Uv Photoelectron Spectroscopy ◽  
Unambiguous Interpretation

Flash vacuum thermolysis (FVT) is a particular method that allows the synthesis of stable compounds or the generation of short-lived species. Its coupling with spectroscopic characterisation provides very useful tools for mechanistic investigations. One of the most efficient and especially well suited techniques for this purpose is ultraviolet–photoelectron spectroscopy (UV-PES), which in tandem with FVT provides the ionisation energies of in situ formed molecules in the gas phase. The experimental data thus obtained in real-time are supported by quantum chemical calculations for consistency of the assignments of PES spectra and constitute fundamental information about electronic structure and bonding. The FVT/UV-PES technique has been known for more than 40 years, but one advantage in the present age is the greater confidence in electronic structure computations for predicting ionisation energies, thus providing the necessary tool for unambiguous interpretation of experimental data. This mini-review aims to give some representative, original examples, chosen from a French–Polish collaboration that illustrates the efficiency and wide applicability of the FVT/UV-PES tandem methodology. The selected examples on the FVT of thione and imine derivatives will be presented.

Study of Sulfur-Sulfur Nonbonded Interactions in Substituted Diphosphine Disulfides by Gas-Phase UV Photoelectron Spectroscopy

1981 ◽  
Vol 36 (1) ◽  
pp. 68-71
Author(s):  
Lucilla Alagna ◽  
Carla Cauletti ◽  
Marco Andreocci ◽  
Claudio Furlani ◽  
Gerhard Hagele
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectra ◽  
Coupling Mechanism ◽  
Nonbonded Interactions ◽  
Lone Pairs ◽  
Uv Photoelectron Spectroscopy

Ultraviolet photoelectron spectra (UPS) of tetrasubstituted diphosphine disulfides RR'P(S)- P(S)RR' exhibit peculiar 1:2:1 splitting patterns in the region 7.5-9.5 eV for which a throughbond coupling mechanism between the sulfur lone pairs lying in the PPS planes is proposed. Further bond orbitals are related to bands at higher I. E. in the UP spectra

Realization of Detailed Kinetic Models for the Growth of II-VI Compounds: Adopting DFT Calculations and Experimental Evidences

1999 ◽  
Vol 584 ◽  
Author(s):  
Carlo Cavallotti ◽  
Valeria Bertani ◽  
Maurizio Masi ◽  
Sergio Carrà
Keyword(s):  
Experimental Data ◽  
Kinetic Theory ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Kinetic Scheme ◽  
Kinetic Constants ◽  
Surface Processes ◽  
Gas Phase Reactions ◽  
Elementary Reactions ◽  
Kinetics Of

AbstractThe kinetics of deposition of CdTe, ZnS and ZnSe films was studied. An overall microkinetically reversible kinetic scheme consisting of elementary reactions, comprehensive of gas phase and surface processes was developed. Kinetic constants of gas phase reactions were either found in the literature or determined through quantum chemistry methods. Kinetic constants of surface reactions were first guessed combining kinetic theory with quantum chemical calculations and then their values were refined to reproduce experimental data. The kinetics schemes so developed were tested through the simulation of deposition reactors. Measured growth rates and gas phase compositions were thus compared with those calculated. The major finding of this studies is that the growth of CdTe, ZnS and ZnSe can be represented adopting a surface kinetic scheme constituted essentially by the same fundamental steps.

Gas phase flash pyrolysis of 3-azido-1,2,4-triazole: generation and ultraviolet photoelectron spectrum of N-cyanomethanimine

1988 ◽  
Vol 66 (9) ◽  
pp. 2123-2129 ◽  
Author(s):  
I. B'Shary ◽  
C. Guimon ◽  
M. Grimaud ◽  
G. Pfister-Guillouzo ◽  
D. Liotard
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectrum ◽  
Reaction Path ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Pyrolysis Gas ◽  
Flash Pyrolysis ◽  
Ionic States ◽  
Configuration Interaction Calculations

A dimer of HCN, N-cyanomethanimine 6, was prepared by flash pyrolysis (gas phase, 10−2 mbar) from 3-azido-1,2,4-triazole 1a and detected by ultraviolet photoelectron spectroscopy (HeI). Its ionization potentials were measured and the ionic states sequence proposed, with the aid of ab initio – CI (configuration interaction) calculations. The study of the MNDO potential hypersurface enabled us to propose a mechanism of the thermal reorganization of the precursor 1a. It is shown that the reaction path passes through the formation of the protomer 1b before thermal decomposition and the generation of the nitrene 2b.

scholarly journals A study of the vacuum pyrolysis of para-substituted diazoacetophenones with He(I) ultraviolet photoelectron spectroscopy

1998 ◽  
Vol 76 (8) ◽  
pp. 1162-1173 ◽  
Author(s):  
Nick H Werstiuk ◽  
Heidi M Muchall ◽  
Jiagong Ma ◽  
Michael TH Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Laser Power ◽  
Spectroscopic Data ◽  
Power Level ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Wolff Rearrangement ◽  
Vacuum Pyrolysis ◽  
The Subject ◽  
Ab Inito

An ultraviolet photoelectron (PE) spectrometer apparatus that utilizes a tuneable 50 W CW CO2 laser as a directed heat source was used to study the vacuum pyrolysis of diazoacetophenone (1a) and its p-methyl, p-methoxy, p-chloro, and p-nitro analogues 1b, 1c, 1d, and 1e. Analysis of the pyrolysate with He(I) ultraviolet PE spectroscopy shows that at a laser power level of 26 W (500 ± 50°C) 1a, 1b, 1c, and 1d, cleanly yield the corresponding phenylketenes 2a, 2b, 2c, and 2d, respectively, the products of the Wolff rearrangement of the incipient ketocarbenes. Of this group of highly reactive ketenes, which cannot be isolated in the condensed phase at ambient temperature, only 2a has been the subject of a previous PE spectroscopic study. But our work indicates that the sample of 2a prepared in the earlier study was impure. The low volatility of p-nitrodiazoacetophenone (1e) thwarted our attempts to generate 2e and obtain its spectrum. Calculations at semiempirical (AM1) and ab inito (HF/6-31G(d)) levels of theory established that the diazoacetophenones prefer to adopt twisted syn conformations. That the calculated ionization potentials (HAM/3 and Becke3LYP/6-31+G(d)//HF/6-31G(d)) of 1a-1d and the synthesized PE spectra of 1a, 1b, and 1c correlate well with the PE spectroscopic data supports this finding. Shifts observed in the three low-energy ionizations of ketenes 2b, 2c, and 2d induced by the para-substitution can be related to the character of the corresponding occupied molecular orbitals of phenylketene (2a).Key words: diazoacetophenones, phenylketenes, He(I) photoelectron spectroscopy, thermolysis, quantum chemical calculations.

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