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Collision-induced conformational changes in glycine

Miller, Thomas F., III and Clary, David C. and Meijer, Anthony J. H. (2005) Collision-induced conformational changes in glycine. Journal of Chemical Physics, 122 (24). Art. No. 244323. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:MILjcp05c

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Abstract

We present quantum dynamical calculations on the conformational changes of glycine in collisions with the He, Ne, and Ar rare-gas atoms. For two conformer interconversion processes (III-->I and IV-->I), we find that the probability of interconversion is dependent on several factors, including the energy of the collision, the angle at which the colliding atom approaches the glycine molecule, and the strength of the glycine-atom interaction. Furthermore, we show that attractive interactions between the colliding atom and the glycine molecule catalyze conformer interconversion at low collision energies. In previous infrared spectroscopy studies of glycine trapped in rare-gas matrices and helium clusters, conformer III has been consistently observed, but conformer IV has yet to be conclusively detected. Because of the calculated thermodynamic stability of conformer IV, its elusiveness has been attributed to the IV-->I conformer interconversion process. However, our calculations present little indication that IV-->I interconversion occurs more readily than III-->I interconversion. Although we cannot determine whether conformer IV interconverts during experimental Ne- and Ar-matrix depositions, our evidence suggests that the conformer should be present in helium droplets. Anharmonic vibrational frequency calculations illustrate that previous efforts to detect conformer IV may have been hindered by the overlap of its IR-absorption bands with those of other conformers. We propose that the redshifted symmetric –CH2 stretch of conformer IV provides a means for its conclusive experimental detection.


Item Type:Article
Additional Information:©2005 American Institute of Physics. Received 17 March 2005; accepted 15 April 2005; published 6 July 2005. Two of the authors (T.F.M. and D.C.C.) acknowledge fellowships from the National Science Foundation and the Leverhulme Trust, respectively. Another author (A.J.H.M.M.) acknowledges funding from the University of Sheffield. The authors thank Dr. Pierre Çarçabal for his helpful comments.
Subject Keywords:organic compounds, helium neutral atoms, neon, argon, atom-molecule collisions, molecular configurations, vibrational states, infrared spectra, red shift
Record Number:CaltechAUTHORS:MILjcp05c
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MILjcp05c
Alternative URL:http://dx.doi.org/10.1063/1.1927527
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11062
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:25 Jun 2008
Last Modified:26 Dec 2012 10:08

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