Kent M. Ervin
Physical and Analytical Chemistry; Chemical Physics
B.S., B.A. (1981), University of Kansas; Ph.D. (1986), University of California, Berkeley (P. B. Armentrout); Postdoctoral (1986-1990), JILA, University of Colorado (W. C. Lineberger).
Office: CB 115
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Kent M. Ervin
Tandem mass spectrometry techniques are used to study chemical systems relevant to combustion kinetics and the dissociation dynamics of molecular ions. Two custom-built tandem mass spectrometers have been developed for these studies: a guided ion beam tandem mass spectrometer with a magnetic sector initial mass spectrometer and a 2D quadrupole final mass spectrometer, and a crossed ion beam/molecular beam apparatus with a 3D quadrupole ion trap initial mass spectrometer and a time-of-flight mass spectrometer for detection. Both systems allow the measurement of ion-molecule reactions as a function of collision energy and time-resolved examination of photodissociation processes. In addition, laser-induced fluorescence studies of ions may be conducted in the ion trap. Current research focuses on the following projects:
Proton transfer and hydrogen atom transfer reactions of organic molecules are used to investigate thermochemical properties of hydrocarbon radicals important in combustion kinetics and environmental chemistry. Reaction threshold energies measured with the guided ion beam mass spectrometer can be related to the R-H bond dissociation energies. Competitive threshold collision-induced dissociation of proton-bound complex ions is used to measure relative gas-phase acidities and proton affinities. Product velocity distributions are investigated to probe microscopic reaction mechanisms and the energy disposal into vibrational and translational degrees of freedom.
Multi-photon dissociation, fluorescence emission, and collisional quenching of cations of molecular dyes have been studied in the quadrupole ion trap/time-of-flight mass spectrometer in collaboration with the Cline research group. The ions are obtained in the gas phase using a electrospray ionization source. These studies provide information on the kinetics of excitation and stabilization of large molecular systems in a controlled environment.
Collision-induced dissociation and photodissociation of biomolecular ions are examined and compared for their utility in bioanalytical chemistry. Systems of interest include polypeptides and oligonucleotides, with or without fluorescent labels.
Nickel, A. A.; Lanorio, J. G.; Ervin, K. M. Energy-resolved collision-induced dissociation of peroxyformate anion: Enthalpies of formation of peroxyformic acid and peroxyformyl radical, J. Phys. Chem. A 2012, DOI: 10.1021/jp302089q (in press).
Dangi, B. B.; Ervin, K. M. Optimization of a quadrupole ion storage trap as a source for time-of-flight mass spectrometry, J. Mass Spectrom. 2012, 47, 41-48.
Dangi, B.B.; Sassin, N.A.; Ervin, K.M. Pulsed ion extraction diagnostics in a quadrupole ion trap linear time-of-flight mass spectrometer. Rev. Sci. Instrum. 2010, 81, 063302.
Sassin, N.A.; Everhart, S.C.; Dangi, B.; Ervin, K.M.; Cline, J.I. Fluorescence and photodissociation of rhodamine 575 cations in a quadrupole ion trap. J. Am. Soc. Mass Spectrom. 2009, 104, 96-104.
Sassin, N.A.; Everhart, S.C.; Cline, J.I.; Ervin, K.M. Photodissociation and collisional cooling of rhodamine 575 cations in a quadrupole ion trap. J. Chem. Phys. 2008, 128, 234305.
Armentrout, P.B.; Ervin, K.M.; Rodgers, M.T. Statistical rate theory and kinetic energy-resolved ion chemistry: Theory and applications. J. Phys. Chem. A 2008, 112, 10071-10085.
Shi, Y.; Ervin, K.M. Hydrogen atom transfer reactions of C2-, C4-, and C6-. Bond dissociation energies of H-C2n- and H-C2n (n = 1,2,3). J. Phys. Chem. A 2008, 112, 1261-1267.
Jia, B.; Ervin, K.M. Threshold collision-induced dissociation of hydrogen-bonded dimers of carboxylic acids. J. Phys. Chem. A 2008, 112, 1773-1782.
Angel, L.A.; Ervin, K.M. Gas-phase acidities and O-H bond dissociation enthalpies of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid. J. Phys. Chem. A 2006, 110, 10392-10403.
Akin, F.A.; Ervin, K.M. Collision-induced dissociation of HS-(HCN): Unsymmetrical hydrogen bonding in a proton-bound dimer anion. J. Phys. Chem. A 2006, 110, 1342-1349.
Akin, F.A.; Ree, J.; Ervin, K.M.; Shin, H.K. Threshold collision-induced dissociation of diatomic molecules: A case study of the energetics and dynamics of O2- collisions with Ar and Xe. J. Chem. Phys. 2005, 123, 064308.
Ervin, K.M.; Armentrout, P.B. Systematic and random errors in ion affinities and activation entropies from the extended kinetic method. J. Mass Spectrom. 2004, 39, 1004-1015.
Angel, L.A.; Ervin, K.M. Competitive threshold collision-induced dissociation: Gas-phase acidity and O-H bond dissociation enthalpy of phenol. J. Phys. Chem. A 2004, 108, 8346-8352.
Angel, L.A.; Ervin, K.M. Gas-phase reactions of the iodide ion with chloromethane and bromomethane: Competition between nucleophilic displacement and halogen abstraction. J. Phys. Chem. A 2004, 108, 9827-9833.