Mass pulsed-electron high-pressure

Kebarle P 1988 Pulsed electron high pressure mass spectrometer Techniques for the Study of Ion-Molecule Reactions ed J M Farrar and W FI Saunders (New York Wiley-Interscience)... 

Concerning the first field of application, the kinetics and equilibrium constants for several halide transfer reactions (equation 1) were measured in a pulsed electron high pressure mass spectrometer (HPMS)4 or in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR)5. From measurements of equilibrium constants performed at different temperatures, experimental values were obtained for the thermochemical quantities AG°, AH° and AS° for the reaction of equation 1. The heat of formation (AH°) of any carbocation of interest, R+, was then calculated from the AH0 of reaction and the AH° values of the other species (RC1, R Cl and R +) involved. 

Structural characterization of (butadiene)tricarbonyliron complexes has been carried out by microwave spectro-scopy/" " solution calorimetry/" pulsed-electron high pressure mass spectrometry/ infrared spectro-scopy/ and vibrational overtone spectroscopy/ Theoretical investigations using DFT have also been reported/ " Extended Hiickel calculations have been employed to study structure and stereodynamic relationships in a variety of ( 7" -diene)iron carbonyl complexes/ ... 

Szule]ko J E and McMahon T B 1991 A pulsed electron beam, variable temperature, high pressure mass... 

Williamson, D.H. Knighton, W.B. Grimsrud, E.P. Effect of Buffer Gas Alterations on the Thermal Electron Attachment and Detachment Reactions of Azu-lene by Pulsed High Pressure Mass Spectrometry. Int. J. Mass Spectrom. 2000, 795/796,481-489. 

The free energy for electron attachememt (AGa°) was determined for perfluorobenzenes C6F5X (X = F, Cl, Br, CF3, COMe, CHO, CN, N02, C6F5, COC6F5) by measuring the electron transfer equilibria with some reference anions A- (A was primarily S02) in a pulsed high pressure mass spectrometer (equation 29)273. 

The equilibrium constant for the case X = Cl and i = 1 agrees well with that obtained in a pulsed electron beam high pressure mass spectrometer, the other data have not been previously reported. 

Gas-phase acidities and basicities for many organic compounds are now available, primarily due to the development within the past decades of three new experimental techniques pulsed high-pressure i.e. 0.1... 1300 Pa) mass spectrometry (HPMS) [22, 23, 118], the flowing afterglow (FA) technique with a fast-flowing gas like helium in the pressure range of ca. 10 . .. 10 Pa [119], and pulsed electron beam, trapped ion cell, ion cyclotron resonance (ICR) spectrometry, carried out at ca. 10 ... 10 Pa [24-26, 115]. 

Szulejkc J E and McMahon T B 1991 A pulsed electron beam, variable temperature, high pressure mass spectrometrio re-evaluation of the proton affinity difference between 2-methylpropene and ammcnia Int. J. Mass Spectrom. Ion Proc. 109 279-94... 

This topic was the subject of the occasional review in last year s volume. " Pulsed electron beam high energy source pressure mass spectrometry has been used in combination with photoelectron spectra to determine the gas-phase basicities of methyl and phenyl tertiary phosphines and also primary phosphines. Fragmentation patterns in the mass spectra of various phosphanes, cyanophosphines, and the naphthyldiphosphine (90) have been described. 

Electron affinities of molecules are of interest not only in gas-phase reactions, e.g. in negative chemical ionization mass spectrometry, but also in the field of condensed-phase chemistry. It is characteristic that negative ions are by far not studied to the same level of detail as the corresponding positive ions. However, during the last decade a large number of EA determinations based on measurements of electron transfer equilibria utilizing pulsed high-pressure mass spectrometry have been reported . ... 

High-pressure mass spectrometry and pulsed high-pressure mass spectrometry have also been a source of thermochemical data for organometaiiic compounds (e.g., proton affinities, electron affinities, and bond dissociation enthalpies). The essential difference between both techniques is the fact that in the former the reactants are produced outside the collision cell. 

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