报告题目：Actinides in the Gas Phase: Clarifying Established Chemistry; Revealing New Chemistry

报 告 人：John K. Gibson (Lawrence Berkeley National Laboratory)

报告时间：2015年5月25日（星期一）上午9:00

报告地点：嘉定园区学术活动中心307

报告简介：

Better understanding and control of the chemistry of the actinide elements is necessary for improvements in technological applications, as well as in environmental remediation.　The actinides furthermore present distinctive scientific opportunities and challenges due to the potential bonding character of the partially occupied 5f orbitals, and relativistic effects resulting from their high nuclear charges.　Advantages of studying metal ion chemistry in the gas phase include the ability to examine molecules and complexes absent perturbations in condensed phase, the feasibility to accurately model such systems, and the accessibility of elusive new chemistry.　An important and unusual aspect of this work is the capability to perform experiments on the actinides from thorium through curium, providing opportunities to reveal variations in chemistry across the series as the occupancy of the 5f orbitals increases.　Electrospray ionization of solutions is employed to produce a variety of ionic molecules and complexes for chemical interrogation in a quadrupole ion trap mass spectrometer.　Two primary types of gas-phase processes are studied:　spontaneous exothermic reactions of ions with neutral gases, and endothermic ion fragmentation via collision induced dissociation.　An example of spontaneous reactions is the exchange of the oxygen atoms in actinyl ions, {O=An=O}+　where An = Pa, U, Np, Pu and Am, with the oxygen atom in water; differences in the efficiency of this process among the actinyls provide insights into enigmatic solution behavior, as well as into variations in the nature of An-O bonding across the series.　Whereas oxo-exchange is an example of exothermic activation of the strong An-O bonds, fragmentation of actinyl complexes comprising the isocyanate ligand, NCO-, has been demonstrated to result in endothermic elimination of CO2 concomitant with conversion of an An-O bond to an An-N bond, an elusive transformation in condensed phase actinide chemistry.　These and other examples of gas-phase actinide ion chemistry will be presented.　A new thrust is to obtain infrared absorption spectra for gas-phase actinide ion complexes.　Initial results reveal the capability of this approach to provide new insights into structures and bonding.

报告人简介：

John K. Gibson　(Lawrence Berkeley National Laboratory)　　　　　　　　　　　　　　　　　　　　　　　　

Education

Ph.D. in Physical Chemistry, University of California, Berkeley, 1983

B.A. in Chemistry with a minor in Mathematics, Boston University, 1979

Professional Experience

2007-Present:　Senior Scientist, Lawrence Berkeley National Laboratory

2000-2007:　Senior Research Staff, Oak Ridge National Laboratory

1986-2000:　Research Staff, Oak Ridge National Laboratory

1983-1986:　Research Associate, Oak Ridge National Laboratory

1983:　　　 Postdoctoral Research Associate, Lawrence Berkeley National Laboratory　

1981-1983:　Graduate Student Research Associate, Lawrence Berkeley National Laboratory

1979-1981:　Graduate Student Teaching Assistant, UC Berkeley

Selected Current Research Interests in Gas-Phase Ion Chemistry

? Fundamental aspects of f-element chemistry probed by mass spectrometry

? Role of the 5f electrons in molecular actinide chemistry probed by ion-molecule reactions

? Actinide molecular bond energies and ionization energies

? Synthesis of novel actinide complexes by fragmentation/decomposition of clusters

? Catalytic processes mediated by bare and ligated actinide ions in the gas phase

? Interplay between theoretical and experimental thermodynamics and mechanisms

? Electrospray ionization mass spectrometry of actinide complexes

? Actinide bio-inorganic chemistry from the bottom up

? Elucidating solution chemistry:　hydration, solvation, hydrolysis and complexation

? Gas-phase cluster synthesis by laser ablation of solids

Dr. Gibson has given close to 80 invited conference/ seminars, and has published over 150 papers in refereed journals.