On the mechanism for vibrational autoionization in H₂

Journal Article · Fri Dec 31 23:00:00 EST 1976 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.434154· OSTI ID:7230200

Dehmer, Patricia M. ^[1]; Chupka, W. A. ^[2]

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1. Argonne National Laboratory (ANL), Argonne, IL (United States)
2. Yale Univ., New Haven, CT (United States), Dept. of Chemistry

The cross sections for the reactions of H₂⁺ with He and Ne to form HeH⁺ and NeH⁺ are known to depend strongly on the H₂⁺vibrational level. When the H₂⁺ reactant ions are produced by autoionization of Rydberg states, the measurement of these cross sections provides a means for studying the final vibrational state distribution of H₂⁺ ions resulting from the autoionization process. Relative cross sections for hydride ion formation were determined for approximately 100 autoionizing Rydberg states in para-H₂ between the H₂⁺²J_g⁺,v=0 and v=6 convergence limits. The relative cross sections for formation of HeH⁺ and NeH⁺ (and thus the final vibrational state distributions of H₂⁺) are nearly the same for all the autoionizing Rydberg states between any two H₂⁺ vibrational convergence limits v and v+1 regardless of the initial vibrational level of the autoionizing state. Combining this observation with elementary considerations, we show that vibrational autoionization proceeds predominantly (≳ 95%) via a Δv=1 mechanism when this channel is energetically allowed. When autoionization via Δv=1 is forbidden, autoionization proceeds predominantly (≳ 75%) via the minimum change in Δv. In cases when autoionization proceeds via Δv≳1, the fraction of ions left in the highest available vibrational level decreases slightly with increasing initial vibrational level.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7230200
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 5 Vol. 66; ISSN JCPSA6; ISSN 0021-9606
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
AUTOIONIZATION
CATIONS
CHARGED PARTICLES
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
HELIUM
HELIUM COMPOUNDS
HELIUM HYDRIDES
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
ION COLLISIONS
ION-ATOM COLLISIONS
IONIZATION
IONS
NEON
NEON COMPOUNDS
NEON HYDRIDES
NONMETALS
RARE GAS COMPOUNDS
RARE GASES