Photoionization of Ar₂ at high resolution

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.443144· OSTI ID:5700760

Dehmer, Patricia M. ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)

The relative photoionization cross section of Ar₂ was determined at a resolution of 0.07 Â in the wavelength region from 800 to 850 Â using a new photoionization mass spectrometer that combines a high intensity helium continuum lamp with a free supersonic molecular beam source. In the region studied, the photoionization cross section is dominated by autoionization of molecular Rydberg states, and the structure is diffuse owing to the combined effects of autoionization and predissociation. The molecular photoionization spectrum is extremely complex and shows little resemblence either to the corresponding atomic spectrum (indicating that the spectrum of the dimer is not simply a perturbed atomic spectrum) or to the molecular absorption spectrum at longer wavelengths. The regular vibrational progressions seen at longer wavelengths are absent above the first ionization potential. Detailed spectroscopic analysis is possible for only a small fraction of the observed features; however, vibrational intervals of 50--100 cm⁻¹ suggest that some of the Rydberg states have B ²Π_3/2g ionic cores. A comparison of the absorption and photoionization spectra shows that, at wavelengths shorter than -835 Â, many of the excited states decay via mechanisms other than autoionization

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5700760
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 3 Vol. 76; 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
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
ARGON
CROSS SECTIONS
DIMERS
ELEMENTS
FLUIDS
GASES
IONIZATION
MOLECULES
NONMETALS
PHOTOIONIZATION
RARE GASES
SPECTRA
ULTRAVIOLET SPECTRA