M.S. (Master of Science)
Department of Chemistry
Dissociation; Mass spectrometry; Aldehydes
An RMU-7 Hitachi Perkin-Elmer spectrometer was modified to allow the study of both the metastable ion (MI) and collision induced dissociation (CID) reactions of acetaldehyde (CH₃CHO) and acetaldehyde -1-d₁ (CH₃CDO). Metastable ion kinetic energy releases (T values) and ion abundance measurements were determined by the high voltage (HV) scanning technique. Mass analyzed Ion Kinetic Energy Spectroscopy (MIKES) was used to determine kinetic energy release values and reactant ion kinetic energy losses (Q values) associated with the collisional excitation of CH₃CHO⁺, CH₃CDO⁺, HCO⁺, and DCO⁺ ions. Ion source fragmentation patterns and collisional activation results are in agreement with predictions based upon the primary isotope effect. The metastable ion decomposition results, however, indicate that some other effect, possibly quantum mechanical tunneling, contributes to the observed T values. This is consistent with a much lower average excess internal energy distribution (ca. 0.1 eV) of the fragmenting molecular ions in metastable ion dissociation relative to that present for ion source or collisionally activated molecular ions (ca. 0.5 eV or more). Other researchers have observed this same effect and have also been unable to satisfactorily explain its source.
Samuelson, William R., "A mass spectrometric study of metastable ion and collision induced dissociation reactions of CH₃CHO and CH₃CDO" (1981). Graduate Research Theses & Dissertations. 392.
v, 68 pages
Northern Illinois University
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