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.

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.

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

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.

Design of a high-resolution mass spectrometer for studying the photodissociation of organic ions in the gas phase

1981 ◽  
Vol 374 (1759) ◽  
pp. 461-473 ◽  
Keyword(s):  
Mass Spectrometer ◽  
Ion Source ◽  
Operating Conditions ◽  
Electron Multiplier ◽  
Electric Sector ◽  
Positive Ions ◽  
Free Region ◽  
Field Free Region ◽  
Ion Laser ◽  
Double Focusing

The design and operating conditions of an apparatus to study photodissociation of ions is described. Ions in a large, double-focusing, mass spectrometer are irradiated with photons from an argon-ion laser. A path length of 706 mm for interaction between the ion and laser beams is obtained by passing the radiation through the ion source and then along the same path as that followed by the ions in the first field-free region of the mass spectrometer. By scanning the voltage of the electric sector, different fragment ions resulting from photodissociation are transmitted in turn to an electron multiplier. They are distinguished from ions resulting from unimolecular dissociation by mechanically chopping the laser beam and using the technique of phase-sensitive detection. The photodissociations of the molecular, positive ions of the three isomers of nitrotoluene have been investigated. It is found that, after excitation of the ions with 2.541 eV photons, the resulting fragmentation pathways are different from those for the corresponding unimolecular dissociations.

Effect of cesium on H− production in a field free region of a volume source

1998 ◽  
Vol 69 (2) ◽  
pp. 974-976 ◽  
Author(s):  
M. Nishiura ◽  
M. Sasao ◽  
M. Wada
Keyword(s):  
Volume Source ◽  
Free Region ◽  
Field Free Region
Sign in / Sign up

Export Citation Format

Share Document