On the origin of metastable decay in Ar sup + sub 2

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.459536· OSTI ID:6741777

Whitaker, B J; Woodward, C A; Knowles, P J; Stace, A J ^[1]

---

1. 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), Journal Name: Journal of Chemical Physics; (USA) Vol. 93:1; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON COMPLEXES
BEAMS
CATIONS
CHARGED PARTICLES
COLLISIONS
COMPLEXES
DISSOCIATION
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ENERGY LEVELS
EXCITED STATES
IONS
MASS SPECTROSCOPY
METASTABLE STATES
MOLECULAR BEAMS
MOLECULAR IONS
MOLECULE COLLISIONS
RADIATIVE DECAY
SPECTROSCOPY