Total dissociative electron attachment cross sections of selected amino acids

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 * orbital. The authors discuss evidence that direct attachment to the lowest * 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 − .

Dependence of E-H transition in argon ICP discharges for treatment of organic molecules

“…H-mode is known to have a higher ion temperature than E-mode [12,13,15] and this is a considerable source of heating in plasmas. Additionally, the higher electron density and electron energy distribution function (EEDF) at lower values, found in H-mode, can also lead to dissociative electron attachment (DEA) on sample surface, which could also increase heating by bond dissociation [26].…”

Low-energy electron collisions with the alanine molecule

“…The lower 2.7 and 3.5 eV resonance energy are associated with the π * unoccupied orbital of the carboxyl group. The broad resonances at 9.8 and 8.6 eV cannot be easily assigned to a specific process, but it has been suggested [71] that it could arise from a core-excited states or σ * unoccupied orbital of OH group [50].…”

“…The most important positive fragments obtained were ions with m/Z of 74, 44 and 28 and appearance energies of 10.74, 9.10 and 10.85 eV, respectively. Total dissociative electron attachment cross sections have been measured for the amino acids glycine, alanine, proline, phenylalanine, and tryptophan, at energies below the first ionization energy by Scheer et al [50].…”

Low energy electron attachment to condensed formic acid

“…It has been already found that DNA damage by LEE, involves electron capture by a particular DNA components followed by the decay into dissociative electron attachment (DEA) and other dissociative channels [12]. Moreover, the common feature in the DEA cross sections of formic acid and some selected amino acids was attributed to the attachment into the -COOH π* orbital, but very recently also the evidence of direct attachment to the lowest σ* orbital was reported [13]. There are many recent experimental studies concerning DEA to the monomeric [14,15,16,17,18,19] and cluster [20] forms of formic acid in the gas phase.…”