On the binding of electrons to nitromethane: Dipole and valence bound anions
- Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)
- Universite Paris-Nord, Institut Galilee/Laboratoire de Physique des Lasers/Unite de Recherche, Associee an au CNRS-URA 282, 93439 Villetaneuse (France)
- Johns Hopkins University, Department of Chemistry, Charles and 34th Streets, Baltimore, Maryland 21218 (United States)
Conventional (valence) and dipole-bound anions of the nitromethane molecule are studied using negative ion photoelectron spectroscopy, Rydberg charge exchange and field detachment techniques. Reaction rates for charge exchange between Cs({ital ns},{ital nd}) and Xe({ital nf}) Rydberg atoms with CH{sub 3}NO{sub 2} exhibit a pronounced maximum at an effective quantum number of {ital n}{asterisk}{approx_equal}13{plus_minus}1 which is characteristic of the formation of dipole-bound anions [{mu}(CH{sub 3}NO{sub 2})=3.46 D]. However, the breadth ({Delta}{ital n}{approx_equal}5, FWHM) of the {ital n}-dependence of the reaction rate is also interpreted to be indicative of direct attachment into a valence anion state via a {open_quote}{open_quote}doorway{close_quote}{close_quote} dipole anion state. Studies of the electric field detachment of CH{sub 3}NO{sup {minus}}{sub 2} formed through the Xe({ital nf}) reactions at various {ital n} values provide further evidence for the formation of both a dipole-bound anion as well as a contribution from the valence bound anion. Analysis of the field ionization data yields a dipole electron affinity of 12{plus_minus}3 meV. Photodetachment of CH{sub 3}NO{sup {minus}}{sub 2} and CD{sub 3}NO{sup {minus}}{sub 2} formed via a supersonic expansion nozzle ion source produces a photoelectron spectrum with a long vibrational progression indicative of a conventional (valence bound) anion with a substantial difference in the equilibrium structure of the anion and its corresponding neutral. Assignment of the origin ({ital v}{prime}=0, {ital v}{double_prime}=0) transitions in the photoelectron spectra of CH{sub 3}NO{sup {minus}}{sub 2} and CD{sub 3}NO{sup {minus}}{sub 2} yields adiabatic electron affinities of 0.26{plus_minus}0.08 and 0.24{plus_minus}0.08 eV, respectively. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 286919
- Journal Information:
- Journal of Chemical Physics, Vol. 105, Issue 9; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Search for {open_quotes}quadrupole-bound{close_quotes} anions. I.
Contribution of electron correlation to the stability of dipole-bound anionic states