Veronica M . Bierbaum

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We present an overview of the interstellar medium, including physical and chemical conditions, spectroscopic observations, and current challenges in characterizing interstellar chemistry. Laboratory studies of ion-atom reactions, including experimental approaches and instrumentation, are described. We also tabulate and discuss comprehensive summaries of(More)
The competition between bimolecular nucleophilc substitution and base-induced elimination is investigated through kinetic isotope effect measurements for gas-phase reactions of RCl + ClO- (R = methyl, ethyl, isopropyl, and tert-butyl) utilizing a FA-SIFT instrument. The overall reaction rate constants and the kinetic isotope effect for the reaction of(More)
Reaction rate constants and deuterium kinetic isotope effects for the reactions of BrOwith RCl (R ) methyl, ethyl, isopropyl, and tert-butyl) were measured using a tandem flowing afterglow-selected ion flow tube instrument. These results provide qualitative insight into the competition between two classical organic mechanisms, nucleophilic substitution(More)
The α-effect-enhanced nucleophilicity of an anion with a lone pair of electrons adjacent to the attacking atom-has been well documented in solution; however, there is continuing disagreement about whether this effect is a purely solvent-induced phenomenon or an intrinsic property of the α-nucleophiles. To resolve these discrepancies, we explore the α-effect(More)
Direct comparisons of the reactivity and mechanistic pathways for anionic systems in the gas phase and in solution are presented. Rate constants and kinetic isotope effects for the reactions of methyl, ethyl, isopropyl, and tert-butyl iodide with cyanide ion in the gas phase, as well as for the reactions of methyl and ethyl iodide with cyanide ion in(More)
Chemical-ionization mass spectrometry (CIMS) using flow reactors is an emerging method for on-line monitoring of trace concentrations of organic compounds in the gas phase. In this study, a flow-reactor CIMS instrument, employing the H(3)O(+) cation as the ionizing reagent, was used to simultaneously monitor several volatile metabolic products as they are(More)
A rapid and highly sensitive method for the detection of formaldehyde utilizing selected ion flow tube-chemical ionization mass spectrometry is reported. Formaldehyde in aqueous biological samples is preconcentrated by distillation and directly analyzed using gas-phase thermal energy proton transfer from H30+; this procedure can be performed in 30 min. The(More)
Selected ion flow tube-chemical ionization mass spectrometry was used to measure formaldehyde levels in human breast cancer cells in comparison with levels in cells treated with the antitumor drugs doxorubicin (DOX) and daunorubicin (DAU) and the daunorubicin-formaldehyde conjugate Daunoform (DAUF). The measurement was performed on cell lysates and showed(More)
The 364-nm photoelectron spectrum of pyrrolide anion, prepared by deprotonation of pyrrole, has been measured. The electron affinity (EA) of pyrrolyl radical has been determined to be 2.145 ( 0.010 eV. Harmonic vibrational frequencies of 925 ( 65, 1012 ( 25, and 1464 ( 20 cm-1 are observed in the spectrum of the A2 ground state of pyrrolyl. This spectrum is(More)