Etude par activation collisionnelle des ions [C4H7O]+ provenant des ions penténols et méthylcetones [C5H10O]•+ métastables

1984 ◽  
Vol 62 (9) ◽  
pp. 1740-1746 ◽  
Author(s):  
G. Bouchoux ◽  
Y. Hoppilliard ◽  
R. Flammang ◽  
A. Maquestiau ◽  
P. Meyrant
Keyword(s):  
Mass Spectrometer ◽  
Collisional Activation ◽  
Molecular Ions ◽  
Side Chain ◽  
Molecular Ion ◽  
Free Region ◽  
Field Free Region

The [C4H7O]+ ions arising from 2-pentanone (1), 3-methylbutanone (2), 2-methylbut-3-en-2-ol (3), pent-3-en-2-ol (4), and 3-methylbut-3-en-2-ol (5) by methyl loss were studied by collisional activation. A triple sector (E/B/E) mass spectrometer was used to distinguish between fragment ion structures produced in the source and in the first field free region. The collision induced dissociations confirm or demonstrate that: (i) in the source, the methyl originally on the position 1 in compounds 1–5 is lost to give, respectively, [n-C3H7CO]+ (a), [i-C3H7CO] + (b), [CH3COHCHCH2] + (c), [CH3CHCHCHOH]+ (d), and [CH2C(CH3)CHOH]+ (e), while the methyl loss from the side chain gives, competitively, ion c for the five precursors; (ii) in the first field free region molecular ions 1,3,4, and 5 produce an identical mixture of structures a, b, and c; the molecular ion 2 leads essentially to acylium ion b. The mechanisms and the thermochemistry of the isomerization path of 1–5 are discussed.

Carbon and hydrogen scrambling in the ions C(9+n)H(9+2n)+. Rearrangements of cyclooctatetraene derivatives

1972 ◽  
Vol 25 (5) ◽  
pp. 1107 ◽  
Author(s):  
JH Bowie ◽  
GE Gream ◽  
M Mular
Keyword(s):  
Mass Spectrometer ◽  
Side Chain ◽  
Free Region ◽  
Field Free Region ◽  
Hydrogen Rearrangement ◽  
Hydrogen Scrambling

Carbon and hydrogen scrambling occurs either prior to, or during, the decompositions of the ions C9H9+, CllH13+, and C12H15+ in the first field-free region of the mass spectrometer. The ions may be produced from various substrates, and the decompositions of CllH13+ may be interpreted in terms of a decomposing ion in which some, but not all, of the C-H bonds have broken and reformed. The ions C9H9+ and C10H11+ may be produced by complex hydrogen rearrangement in the side-chain of particular bromo-and hydroxy-alkylcyclooctatetraene derivatives.

The ionization of fast neutrals by electron impact in the second field-free region of a mass spectrometer of reversed geometry

1988 ◽  
Vol 23 (6) ◽  
pp. 495-498 ◽  
Author(s):  
M. C. Blanchette ◽  
J. L. Holmes ◽  
C. E. C. A. Hop ◽  
A. A. Mommers
Keyword(s):  
Electron Impact ◽  
Mass Spectrometer ◽  
Free Region ◽  
Field Free Region

Correlations between spectroscopic properties of aromatic molecules and fragmentation rates of their metastable molecular ions in a mass spectrometer

1982 ◽  
Vol 60 (19) ◽  
pp. 2484-2499 ◽  
Author(s):  
Robert K. Boyd ◽  
Bori Shushan
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Mass Spectrometer ◽  
Aromatic Hydrocarbons ◽  
Spectroscopic Properties ◽  
Molecular Ions ◽  
Steric Interaction ◽  
Quasi Equilibrium ◽  
Ancillary Data ◽  
Free Region ◽  
Polycyclic Aromatic

Unexpected correlations have been found between spectroscopic (uv and nmr) properties of some aromatic systems (specifically polycyclic aromatic hydrocarbons and chlorinated biphenyls) and fragmentation rates of the corresponding metastable molecular ions in a field-free region of a mass spectrometer. The meaning of these empirical correlations is explored via the quasi-equilibrium theory of mass spectra. For the case of the polycyclic aromatic hydrocarbons for which more complete ancillary data are available, a reasonably self-consistent account of the correlations can be obtained via the ionisation energy as the crucial parameter. The case of the chlorinated biphenyls is less clear, due to a lack of subsidiary data. However, the best explanation available appears to involve a systematic shift in the energy deposition function with increasing steric interaction around the biphenyl linkage.

Alteration of the benzene molecular ion and substituted benzene molecular ions by their mode of formation in the mass spectrometer

1969 ◽  
Vol 10 (40) ◽  
pp. 3469-3472 ◽  
Author(s):  
Maurice K. Bursey ◽  
Fred E. Tibbetts ◽  
William F. Little ◽  
Marvin D. Rausch ◽  
Glenn A. Moser
Keyword(s):  
Mass Spectrometer ◽  
Molecular Ions ◽  
Molecular Ion

The Ion Kinetic Energy Spectra of Benzyl Fluoride and the Isomeric Fluorotoluenes

1974 ◽  
Vol 52 (6) ◽  
pp. 867-869 ◽  
Author(s):  
S. Safe ◽  
W. D. Jamieson ◽  
D. J. Embree
Keyword(s):  
Mass Spectrometry ◽  
Kinetic Energy ◽  
Mass Spectrometer ◽  
Aromatic Compounds ◽  
Mass Spectra ◽  
Energy Spectra ◽  
Model Compounds ◽  
Free Region ◽  
Field Free Region ◽  
Ion Kinetic Energy

One of the classical problems in mass spectrometry is the structure and formation of the C7H7+ and XC7H6+ ions which are generated in the mass spectra of alkylbenzenes and many other aromatic compounds. The intermediacy of both symmetrical tropylium ion structures and unsymmetrical benzyl ions has been postulated using a number of different approaches. We have investigated this problem using ion kinetic energy spectroscopy, a relatively new technique, with the isomeric fluorobenzenes and benzyl fluoride as model compounds. Our results indicated incomplete substituent (i.e. fluorine) scrambling in the first field-free region of the mass spectrometer and thus incomplete equilibration in the decomposing FC7H6+ ions and these conclusions are in contrast to results obtained using other techniques.

scholarly journals Kinetic Energy Release in Metastable Transitions. I

1967 ◽  
Vol 22 (1) ◽  
pp. 15-19 ◽  
Author(s):  
M. Barber ◽  
K. R. Jennings ◽  
R. Rhodes
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Mass Spectrometer ◽  
Kinetic Energy Release ◽  
Peak Shape ◽  
Free Region ◽  
Field Free Region ◽  
Product Ions ◽  
Electrostatic Analyser

A method is described for detecting metastable transitions which take place with the release of kinetic energy in the field-free region between the source and electrostatic analyser of a doublefocusing mass spectrometer, and a procedure is given for evaluating the kinetic energy release. Values are given for a number of transitions and are in agreement with those obtained by other methods where comparison is possible. The variation of peak shape with accelerating voltage is ascribed to the varying efficiency with which product ions are collected.

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