Constant-ionic-state spectroscopy of high-v Rydberg states of molecular hydrogen

Journal Article · Tue Dec 31 23:00:00 EST 1991 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.463045· OSTI ID:7156779

Pratt, Stephen T. ^[1]; Dehmer, Patricia M. ^[1]; Dehmer, Joseph L. ^[1]

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

The (X ²Σ⁺_g)np Rydberg states converging to the X ²Σ⁺_g, v⁺≥9 ionization thresholds of molecular hydrogen were excited by double-resonance excitation via the E,F ¹Σ⁺_g, v=6 level. The energy region of interest (139 500--140 000 cm⁻¹) included the X ²Σ⁺_g, v⁺=9, N⁺=0--3 ionization thresholds as well as the energetic threshold for ion pair formation. The decay of the autoionizing Rydberg states was studied by both conventional and constant-ionic-state photoelectron spectrometry. The results support the Δv=minimum propensity rule for vibrational autoionization of Rydberg states with a high level of vibrational excitation. However, the relative intensities of the (X ²Σ⁺_g)np, v'≥9 Rydberg series converging to different rotational levels of the ion are dramatically different from those for the analogous Rydberg series with v'≤2. In addition, the two-color photoelectron spectrum via the E,F ¹Σ⁺_g, v=6 level shows considerable intensity in the v⁺=7 and 8 photoelectron bands both on and off resonance, in marked contrast with the single-color photoelectron spectrum obtained for the same intermediate levels. These observations may be due to the dependence of the transition dipole matrix elements on the internuclear distance and to the presence of doubly excited electronic states that cross the H₂⁺ X ²Σ⁺_g potential curve at a total energy close to that accessed by the two-color excitation scheme.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE; Office of Energy Research (OER); Office of Health and Environmental Research (OHER)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7156779
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 5 Vol. 97; ISSN JCPSA6; ISSN 0021-9606
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
AUTOIONIZATION
DIPOLES
DOUBLE RESONANCE METHODS
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
HYDROGEN
ION PAIRS
ION SPECTROSCOPY
IONIZATION
MATRIX ELEMENTS
MOLECULES
MULTI-PHOTON PROCESSES
MULTIPOLES
NONMETALS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
RYDBERG STATES
SPECTROSCOPY
THRESHOLD ENERGY
VIBRATIONAL STATES