scholarly journals Photoelectron spectroscopy of reactive intermediates

Recent developments in the use of photoelectron spectroscopy to study reactive intermediates in the gas phase are reviewed. The information to be derived on low-lying cationic states from such studies is illustrated by considering two diatomic molecules, NCI and PF, and one triatomic molecule, HNO. Also, the use of a transition-metal photoelectron spectrum to interpret the photoelectron spectrum of the corresponding transition-metal oxide is discussed by using the spectra of vanadium and vanadium monoxide as examples. The value of super-heating in high-temperature photoelectron spectroscopy is demonstrated by considering the vapour-phase photoelectron spectra of the monomers and dimers of sodium hydroxide.

2006 ◽  
Vol 84 (4) ◽  
pp. 546-554 ◽  
Author(s):  
N H Werstiuk ◽  
A Klys ◽  
J Warkentin

Gas-phase pyrolysis of 2-methoxy-2-methylsulfanyl-5,5-dimethyl-2,5-dihydro[1,3,4]oxadiazole (1) (also known as 2-methoxy-5,5-dimethyl-2-methylthio-2,5-dihydro[1,3,4]oxadiazole and 2-methoxy-2-methylthio-5,5-dimethyl-Δ3-l,3,4-oxadiazoline) in the source of an UV photoelectron spectrometer, by means of a CW CO2 laser as directed heat source, gave a photoelectron (PE) spectrum that included ionization bands belonging to acetone and methoxy(methylthio)carbene (3). Photoelectron spectra of authentic samples of (E)-1,2-dimethoxy-1,2-dimethyl thioethene (4), (Z)-1,2-dimethoxy-1,2-dimethylthioethene (5), S-methyl thioethanoate (6), and O-methyl ethanethioate (7), which can be derived by dimerization and rearrangement of the carbene, established that these compounds are not present in the pyrolysate. DFT calculations at the B3PW91/6-31+G(d,p) level and simulation of PE spectra at the B3LYP/6-31+G(d,p) level were instrumental in the interpretation of the experimental results. From the available experimental and calculated data, 3 is formed in a Sickle conformation upon pyrolysis of 1. Transition states for the rearrangement of 3 were examined with QTAIM. Key words: 2-methoxy-5,5-dimethyl-2-methylthio-2,5-dihydro[1,3,4]oxadiazole, pyrolysis, He(I) photoelectron spectroscopy, methoxy(methylthio)carbene, DFT calculations, QTAIM.


2002 ◽  
Vol 09 (01) ◽  
pp. 583-586
Author(s):  
KOTA IWASAKI ◽  
KOICHIRO MITSUKE

A new angle-resolving electron energy analyzer composed of a conical electrostatic prism and a position-sensitive detector was developed for gas phase photoelectron spectroscopy. The performance of the analyzer has been tested by measuring photoelectron spectra of Ar using a helium discharge lamp. The angular resolution of 3° was achieved at the pass energy E of 5.6 eV. The best energy resolution was ΔE/E = 0.043 at E = 1.4 eV .


1981 ◽  
Vol 36 (11) ◽  
pp. 1246-1252 ◽  
Author(s):  
Michael H. Palmer ◽  
Isobel Simpson ◽  
J. Ross Wheeler

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.


1981 ◽  
Vol 36 (1) ◽  
pp. 68-71
Author(s):  
Lucilla Alagna ◽  
Carla Cauletti ◽  
Marco Andreocci ◽  
Claudio Furlani ◽  
Gerhard Hagele

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


1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price

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]


The He I photoelectron spectra of the chlorides, bromides and iodides of magnesium, strontium and barium (except Mgl 2 ) and of BeCl 2 have been recorded in the vapour phase by the use of a molecular beam technique. Contrary to the study of Hammer et al . (1978) considerable structure was served. Ab initio s. c. f. m. o. calculations were carried out for the lighter members of the group and the calculated ionization potentials allowing for the effects of spin–orbit coupling compared with those obtained from the spectra. In this way valence shell electronic configurations for the mole­cules studied were determined. Evidence for a nonlinear geometry of the heavier metal halides is also discussed both in terms of spectral features expected for a nonlinear geometry from s. c. f. calculation and from a point charge model.


1998 ◽  
Vol 76 (2) ◽  
pp. 238-240
Author(s):  
H M Muchall ◽  
N H Werstiuk ◽  
B Choudhury ◽  
J Ma ◽  
J Warkentin ◽  
...  

Gas phase thermolysis of 2,2-dimethoxy-5,5-dimethyl- Δ3-1,3,4-oxadiazoline (1) in an ultraviolet photoelectron spectrometer by means of a CW CO2 laser as directed heat source at 26 W gave a complex PE spectrum that included ionization bands belonging to acetone, tetramethoxyethylene (3), and dimethyl oxalate (4). Subtraction of the spectra of acetone, 3, and 4 from the pyrolysis spectrum of 1 left a simple PE spectrum that is attributed to dimethoxycarbene (2) along with some ethane. ecke3LYP/6-31+G* calculations gave first adiabatic and vertical ionization potentials of 2 as well as orbital energies that are in perfect agreement with experimental values. From the available experimental and calculational data, 2 is assumed to adopt a w conformation.Key words: dimethoxycarbene, 2,2-dimethoxy- Δ3-1,3,4-oxadiazoline, tetramethoxyethylene, He(I) photoelectron spectroscopy, thermolysis.


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