On the origin of metastable decay in Ar sup + sub 2
- School of Molecular Sciences, University of Sussex, Brighton BN1 9QJ (United Kingdom)
Metastable Ar{sup +}{sub 2} (Ar{sup +}{sub 2} {r arrow}Ar{sup +}+Ar) has been observed in a double-focusing mass spectrometer from ions created by 70 eV electron bombardment of an Ar cluster beam. New ground and excited state potential energy curves have been calculated for Ar{sup +}{sub 2}, and these have been used to show that metastability is due to radiative decay from the II(1/2){sub {ital u}} state of the ion. It is shown that vertical (FC) ionization from neutral Ar{sub 2}, with a vibrational temperature of approximately 30 K, results in a significant fraction of the ions occupying the II(1/2){sub {ital u}} state. Detailed pressure dependent measurements show that collision-induced dissociation does not contribute to the observed Ar{sup +} signal. The mean kinetic energy released to the Ar{sup +} has been measured as 44 cm{sup {minus}1} in the center-of-mass frame, and calculations show that this value is consistent with the proposed mechanism.
- OSTI ID:
- 6741777
- Journal Information:
- Journal of Chemical Physics; (USA), Vol. 93:1; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARGON COMPLEXES
ELECTRON-MOLECULE COLLISIONS
RADIATIVE DECAY
CATIONS
DISSOCIATION
MASS SPECTROSCOPY
METASTABLE STATES
MOLECULAR BEAMS
MOLECULAR IONS
BEAMS
CHARGED PARTICLES
COLLISIONS
COMPLEXES
ELECTRON COLLISIONS
ENERGY LEVELS
EXCITED STATES
IONS
MOLECULE COLLISIONS
SPECTROSCOPY
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena