Mass spectrometric studies of gaseous cluster ions
Mass spectrometric studies of gaseous cluster ions
Clusters of a series of lower aliphatic alcohols representing primary, secondary, and tertiary alcohols and acetone have been produced by their adiabatic expansion in a supersonic molecular beam system which has been developed for this study. Fragmentations of the ion clusters have been studied on electron impact ionization of the neutral beams. The fragmentation pathways have been confirmed by their metastable and collision-induced dissociations. In the case of alcohols, protonated cluster ions,. (ROH) H+, are formed while in acetone both the protonated, (CH3000H3)0H+, nas well as simple cluster ions, (CH3000H3)n+, are formed on ionization of their respective cluster beams. The cluster fragmentation processes in all cases, except in primary alcohols, are those which are the most common processes in the mass spectra of their parent molecules. In alcohols, the dehydration reactions of the protonated cluster ions and fragment ions constitute a major part of the reaction sequences observed. The low energy cluster ion spectrum of acetone has been calculated using the RRKM theory. The calculated spectrum at 18 eV is in good agreement with the observed spectrum suggesting that the theory can be extended to more complex ions such as these. The results further suggest that the energy distribution in the cluster ions is similar to that of the acetone molecule ion. Using the quasi-equilibrium theory, an attempt has been made to reproduce experimental peak profiles resulting from the collisioninduced dissociation of ethanol, 1-propanol, and acetone ions. The calculations show that the peak profiles are insensitive to the details of the collisional energy transfer distribution but that the shape of the peaks is influenced by changes in the kinetic energy release distribution. Preliminary results on the kinetic energy released from metastable dissociations of C02 and H20 cluster ions and from the collisioninduced dissociation of C02 cluster ions are also presented.
University of Southampton
1981
Shukla, Anil Kumar
(1981)
Mass spectrometric studies of gaseous cluster ions.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Clusters of a series of lower aliphatic alcohols representing primary, secondary, and tertiary alcohols and acetone have been produced by their adiabatic expansion in a supersonic molecular beam system which has been developed for this study. Fragmentations of the ion clusters have been studied on electron impact ionization of the neutral beams. The fragmentation pathways have been confirmed by their metastable and collision-induced dissociations. In the case of alcohols, protonated cluster ions,. (ROH) H+, are formed while in acetone both the protonated, (CH3000H3)0H+, nas well as simple cluster ions, (CH3000H3)n+, are formed on ionization of their respective cluster beams. The cluster fragmentation processes in all cases, except in primary alcohols, are those which are the most common processes in the mass spectra of their parent molecules. In alcohols, the dehydration reactions of the protonated cluster ions and fragment ions constitute a major part of the reaction sequences observed. The low energy cluster ion spectrum of acetone has been calculated using the RRKM theory. The calculated spectrum at 18 eV is in good agreement with the observed spectrum suggesting that the theory can be extended to more complex ions such as these. The results further suggest that the energy distribution in the cluster ions is similar to that of the acetone molecule ion. Using the quasi-equilibrium theory, an attempt has been made to reproduce experimental peak profiles resulting from the collisioninduced dissociation of ethanol, 1-propanol, and acetone ions. The calculations show that the peak profiles are insensitive to the details of the collisional energy transfer distribution but that the shape of the peaks is influenced by changes in the kinetic energy release distribution. Preliminary results on the kinetic energy released from metastable dissociations of C02 and H20 cluster ions and from the collisioninduced dissociation of C02 cluster ions are also presented.
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Published date: 1981
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Local EPrints ID: 459712
URI: http://eprints.soton.ac.uk/id/eprint/459712
PURE UUID: 75639735-d418-49dc-8cf3-c07b50fd4641
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Date deposited: 04 Jul 2022 17:17
Last modified: 04 Jul 2022 17:17
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Author:
Anil Kumar Shukla
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