Research Papers in Physics and Astronomy

 

Date of this Version

April 2007

Comments

Published in THE JOURNAL OF CHEMICAL PHYSICS 126, 174301 2007. © 2007 American Institute of Physics. Used by permission.

Abstract

Total dissociative electron attachment cross sections are presented for the amino acids, glycine, alanine, proline, phenylalanine, and tryptophan, at energies below the first ionization energy. Cross section magnitudes were determined by observation of positive ion production and normalization to ionization cross sections calculated using the binary-encounter-Bethe method. The prominent 1.2 eV feature in the cross sections of the amino acids and the closely related HCOOH molecule is widely attributed to the attachment into the –COOH π * orbital. The authors discuss evidence that direct attachment to the lowest σ * orbital may instead be responsible. A close correlation between the energies of the core-excited anion states of glycine, alanine, and proline and the ionization energies of the neutral molecules is found. A prominent feature in the total dissociative electron attachment cross section of these compounds is absent in previous studies using mass analysis, suggesting that the missing fragment is energetic H−.

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