Abstract

Molecular orbital calculations were used to study the energetics of four different mechanisms used to explain the collision-induced decomposition mass spectra of saturated fatty acid carboxylate anions produced by fast atom bombardment and chemical ionization. The most abundant homologous series of anions, terminally unsaturated carboxylate anions, arose from the concerted cleavage of <i>gauche</i> segments of the hydrocarbon backbone via a six-atom transition state. A series of anions of lower abundance arose by homolytic cleavage of <i>anti</i> segments of the hydrocarbon backbone into two radical fragments. The loss of methane from the parent anion is produced by the concerted cleavage of the terminal methyl group via a four-atom transition state. The computed activation energies for the reaction mechanisms were in the following order: six-atom transition state < four-atom transition state ≪ homolytic cleavage of hydrocarbon backbone. Dehydration of the parent anion is rationalized to occur by loss of a carboxylate oxygen and two hydrogen atoms on the alpha carbon from the carboxylate carbon.

Effect of hydrocarbon molecular decomposition on palladium-assisted laser-induced plasma ablation

Alireza Moosakhani, Parviz Parvin, Seyedeh Zahra Mortazavi, Ali Reyhani, and Shariar Abachi
Appl. Opt. 56(11) E64-E71 (2017)

Molecular Beam Studies of Internal Excitation of Reaction Products

D. R. Herschbach
Appl. Opt. 4(S1) 128-144 (1965)

Far Ultraviolet Spectrophotometric Studies of Fatty Acids by Photoelectric and Spectrographic Methods*†

D. M. Kerns, R. Belkengren, Harold Clark, and Elmer S. Miller
J. Opt. Soc. Am. 31(3) 271-279 (1941)

Utility of Gaussian-Type Orbitals in Molecular Collisions: Electronic Excitation of the First Positive System of the Nitrogen Molecule

S. Chung and Chun C. Lin
Appl. Opt. 10(8) 1790-1794 (1971)

Measurement of Energy Transfer in Molecular Collisions

A. B. Callear
Appl. Opt. 4(S1) 145-170 (1965)