Studies of Structure and Reactions by Mass Spectrometry 1947-67

Techniques initially devised for analysis of isotopic abundances of volatile mixtures have been extended to the study of the structure of complex molecules and to the investigation of ion-molecule reactions. Brookhaven has pioneered in both areas.

The mass spectrum of ketene dimer, whose structure was unknown, was compared with the spectra of six known compounds in the first attempt to use the mass spectrum of a molecule as a guide to the determination of structure. This study was followed by the successful utilization of the technique in an investigation of structure of metal dicyclopentadienyl compounds. Organic molecular structural analysis by mass spectrometry is now rather standard practice.

In the field of ion-molecule reactions, this laboratory was the first to demonstrate the nature of energy transfer processes in H2+ ion-molecule reactions. The role of internal energy of excitation produced by the electron impact ionization process had not been generally recognized prior to 1962; it was first discussed in a quantitative fashion in studies of the H2+-He and H2+-Ne reactions. These studies and the early investigations of intramolecular isotope effects in HD ion-molecule reactions showed that with these relatively simple systems, failure to observe the theoretically predicted E-1/2 dependence for some reaction cross-sections is not due to breakdown of theory but is the result of the failure to observe important energy dependent channels of reaction.

In the area of high temperature chemistry, the first mass spectrometric study of alkali halide vapor in which the existence of polymeric species was demonstrated and in which the heat of formation was obtained was made at BNL. This work was followed by a large number of similar investigations at other laboratories.

F. A. Long and L. Friedman, "Mass Spectra and Appearance Potentials of Ketene Monomer and Dimer; Relation to Structure of Dimer," J. Am. Chem. Soc. 21, 2837 (1953).
L. Friedman, A. P. Irsa, and G. Wilkinson, "Mass Spectra of Cyclopentadienyl Metal Compounds. Part I. Bis-Cyclopentadienyl. Compounds of V, Cr, Fe, Co, Ni, Re, and Ru, and Manganese and Magnesium Cyclopentadienides," J. Am. Chem. Soc. 72, 3689 (1955).
L. Friedman, "The Mass Spectrum of Lithium Iodide," J. Chem. Phys. 23, 477 (1955).
F. S. Klein and L. Friedman, "Intramolecular Isotope Effects in the HD-Rare Gas Ion-Molecule Reactions," J. Chem. Phys. 41, 1789 (1964).

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Last Modified: June 28, 2012