PolyU IR
 

PolyU Institutional Repository >
Applied Biology and Chemical Technology >
ABCT Journal/Magazine Articles >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/5045

Title: A study of the dissociation of CH₃CH₂SH⁺ by collisional activation: evidence of nonstatistical behavior
Authors: Chen, Y.-J.
Stimson, S.
Fenn, P. T.
Ng, C. Y.
Li, Wai-kee
Ma, N. L.
Subjects: Ab initio calculations
Organic sulfur compounds
Cations
Dissociation
Ion-atom collisions
Argon
Chemical reaction kinetics
Charge exchange
Photoionization
Total cross sections
Issue Date: 15-May-1998
Publisher: American Institute of Physics
Citation: Journal of chemical physics, 15 May 1995, v. 108, no. 19, p. 8020-8028.
Abstract: The absolute total cross sections for CH₃CH₂⁺, C₂H₄⁺,C₂H₃⁺,CH₃⁺,CH₂SH⁺(CH₃S⁺), CH₂S⁺(HCSH⁺), CHS⁺(CSH⁺), and H₂S⁺ produced by the collision-induced dissociation (CID) reaction of CH₃CH₂SH⁺+Ar have been measured in the center-of-mass collision energy (E[sub c.m.]) range of 1–42 eV. Using the charge transfer probing technique, we found that the mass 47 product ions have overwhelmingly the CH₂SH⁺ structure. The onsets for CH₃CH₂⁺, C₂H₄⁺, C₂H₃⁺, CH₂SH⁺, H₂S⁺, and CH₃⁺ are consistent with their corresponding thermochemical thresholds. The formation of the higher energy channels CH₃CH₂⁺+sH and CH₃+CH₂SH⁺, which involve the C–S and C–C bond scissions, are found to dominate in the entire E[sub c.m.]) range. The lower energy channel corresponding to the formation of CH₃CHSH⁺+H is not found. The strong preference observed for the formation of the higher energy channels is in accord with the conclusion obtained in the recent CID study of CH₃SH⁺, providing evidence that the CID of CH₃CH₂SH⁺ is also nonstatistical. The high yields of CH₃CH₂⁺+SH and CH₂SH⁺+CH₃are attributed to the more efficient translational to vibrational energy transfer for the low frequencies C–S and C–C stretching modes than for the high frequencies C–H and S–H stretching modes, along with the weak couplings between these low and high frequencies vibrational modes of CH₃CH₂SH⁺. The relative abundances of product ions formed by the single-photon ionization of CH₃CH₂SH were also measured for comparison with the CID results. The CH₃CHSH⁺+H channel is observed in the photoionization of CH₃CH₂SH. Similar to the finding in the photoionization of CH₃SH, the relative abundances of fragment ions formed in the photoionization of CH₃CH₂SH are in qualitative accord with statistical predictions. To rationalize the dissociation mechanisms of CH₃CH₂SH⁺, we have also performed ab initio calculations to locate the possible transition structures for the observed dissociation channels.
Description: DOI: 10.1063/1.476241
Rights: © 1998 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Y.-J. Chen et al., J. Chem. Phys. 108, 8020 (1998) and may be found at http://link.aip.org/link/?jcp/108/8020.
Type: Journal/Magazine Article
URI: http://hdl.handle.net/10397/5045
ISSN: 0021-9606 (print)  
1089-7690 (online)
Appears in Collections:ABCT Journal/Magazine Articles

Files in This Item:

File Description SizeFormat
Chen_Study_dissociation_collisional.pdf805.81 kBAdobe PDFView/Open



Facebook Facebook del.icio.us del.icio.us LinkedIn LinkedIn


All items in the PolyU Institutional Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
No item in the PolyU IR may be reproduced for commercial or resale purposes.

 

© Pao Yue-kong Library, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
Powered by DSpace (Version 1.5.2)  © MIT and HP
Feedback | Privacy Policy Statement | Copyright & Restrictions - Feedback