Determination of kinetic energy release from metastable peak widths: An investigation of the instrument-dependence

2018 ◽  
Vol 429 ◽  
pp. 14-17 ◽  
Author(s):  
Allan C. Petersen ◽  
Theis I. Sølling
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Kinetic Energy Release ◽  
Metastable Peak ◽  
Peak Widths

The mass spectra of pyrimidines. II. 2(1H)-Pyrimidinethiones and some N(1)-substituted derivatives

1984 ◽  
Vol 62 (11) ◽  
pp. 2340-2343 ◽  
Author(s):  
Robin T. B. Rye ◽  
Oswald S. Tee ◽  
Eva M. Kazdan
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Mass Spectra ◽  
Kinetic Energy Release ◽  
Exact Mass ◽  
Metastable Peak ◽  
Fragmentation Pathways

The EI induced fragmentation of 2(1H)-pyrimidinethione (1), some N(1)-substituted derivatives, and 2(1H)-pyrimidineselenone (4) have been studied. Principal fragmentation pathways have been identified using 2H-labelling, metastable defocussing, and exact mass measurements.The fragmentations of 1 and 4 generally parallel those reported for 2(1H)-pyrimidinone. In contrast to the oxo-compound, however, direct expulsion of the exocyclic hetero atom is significant in the fragmentation of 1, and dominates the spectrum of 4.Based on metastable peak abundances and kinetic energy release measurements, it is postulated that the [M – H]+ entity generated from N-ethyl-2-pyrimidinethione has a thiazolinium structure.

The Role of Long-Range Forces in the Determination of Translational Kinetic Energy Release. Loss of C4H4+from the Benzene and Pyridine Cations

2008 ◽  
Vol 112 (41) ◽  
pp. 10086-10095 ◽  
Author(s):  
E. Gridelet ◽  
R. Locht ◽  
A. J. Lorquet ◽  
J. C. Lorquet ◽  
B. Leyh
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Long Range ◽  
Kinetic Energy Release

scholarly journals Ringöffnung CO+- und COOCH3+·-substituierter Cyclopropane und CO-Eliminierung aus isomeren C3H5CO+-Ionen / Ring Opening of CO+ and COOCH3+· Substituted Cyclopropanes and CO Loss from Isomeric C3H5CO+ Ions

1979 ◽  
Vol 34 (3) ◽  
pp. 488-494 ◽  
Author(s):  
Helmut Schwarz ◽  
Chrysostomos Wesdemiotis
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Ring Opening ◽  
Collisional Activation ◽  
Kinetic Energy Release ◽  
Ester Group ◽  
Molecular Ions ◽  
Peak Shape ◽  
Metastable Peak ◽  
Substituted Cyclopropanes

Abstract The non-decomposing molecular ions of methyl cyclopropanecarboxylate (14) are found to rearrange to ionised methyl but-3-enoate (15). For ions with sufficient internal energy to decompose, this isomerization is in competition with · OCH3 loss, via direct cleavage of the ester group. Collisional activation spectroscopy may be used to distinguish between the C3H5CO+ ions formed by · OCH3 loss from the molecular ions of 14, 15 and other isomeric precursors. Four distinct C3H5CO+ species (18-21) can be identified in this way; these C3H5CO+ ions may themselves decompose, via CO elimination. Consideration of the metastable peak shape for CO loss, in conjunction with collisional activation spectroscopy on the resulting C3H5+ -ions, leads to two main conclusions, (i) Two C3H5+ ions (22 and 27) exist in potential energy wells. The very narrow metastable peaks for CO loss from 19 and 21 (leading to 22 and 27, respectively) show that these processes are continuously endothermic. In contrast, CO loss from either 18 or 20 gives rise to much broader metastable peaks. This suggests that rate-determining rearrangement of the incipient C3H5+ cations, to a more stable isomer, occurs prior to decomposition, (ii) Elimination of CO from the [M- · OCH3]+ fragment of 14 gives rise to a composite metastable peak, thus indicating the occurrence of two competing channels for dissociation. These channels are assigned to CO loss from 18 (larger kinetic energy release) and CO loss from 19 (smaller kinetic energy release).

The structure and fragmentation of protonated carboxylic acids in the gas phase

1979 ◽  
Vol 57 (21) ◽  
pp. 2827-2833 ◽  
Author(s):  
Nora E. Middlemiss ◽  
Alex. G. Harrison
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Gas Phase ◽  
Activation Barrier ◽  
Kinetic Energy Release ◽  
Drift Region ◽  
Metastable Peak ◽  
Butyl Esters ◽  
Peak Intensity ◽  
A Minor

Gaseous protonated acids fragment in the first drift region of a double focussing mass spectrometer to yield the corresponding acylium ion and water. The metastable peaks for this fragmentation reaction have been recorded for the protonated acids from acetic to valeric and the kinetic energy release distributions evaluated from the metastable peak shapes. The protonated acids were produced by dissociative ionization of the ethyl, propyl, and butyl esters. The results provide evidence for two structures for gaseous protonated acids. Fragmentation of the hydroxyl protonated structure, a minor contributor to the metastable peak intensity, shows a low kinetic energy release (T(most probable) = 0.02 eV) as would be expected for a simple bond fission reaction. Fragmentation of the carbonyl protonated acid, which represents the major part of the metastable peak, is accompanied by a muchlarger kinetic energy release (T(most probable) = 0.30 to 0.43 eV). This result is interpreted in terms of an activation barrier for fragmentation of the carbonyl protonated acid which is considerably greater than the reaction endothermicity, with the excess energy being partitioned between internal energy and kinetic energy of the fragments. The results indicate that the addition of the acylium ion to water in the gas phase to produce the carbonyl protonated acid has an activation energy barrier.

A method for calculating the shapes of peaks resulting from fragmentations of metastable ions in a mass spectrometer. II. Peak shapes arising from a distribution of kinetic energy releases: determination of distribution function

1980 ◽  
Vol 373 (1752) ◽  
pp. 13-25 ◽  
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Preceding Paper ◽  
Kinetic Energy Release ◽  
Peak Shape ◽  
Doubly Charged Ions ◽  
Metastable Ions ◽  
Product Ions ◽  
Doubly Charged

Following the calculations described in the preceding paper (part I), which determine the MIKE peak shape arising from a discrete kinetic energy release, a method is presented for extending the calculations for the determination of the kinetic energy release distribution, n (T), from any experimental peak shape. This new approach has the advantage, compared to previous work, that the distribution can be obtained directly and does not involve any trial and error methods. It applies equally well where discrimination occurs against some of the product ions having components of velocity parallel to the length of the instrument slits. A variety of peak shapes have been investigated and several examples are given of the energy release distribution for various ionic reactions. Charge separation reactions of doubly-charged ions have been examined and in one case, the reaction 91 2+ -> 52 + in toluene, the energy release function exhibits fine structure, which has not previously been observed.

Sign in / Sign up

Export Citation Format

Share Document