Selective population of spin--orbit levels in the autoionization of a polyatomic molecule: Branching ratios and asymmetry parameters for the Tanaka--Ogawa Rydberg series in CO₂

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.466731· OSTI ID:7307535

Parr, Albert C. ^[1]; Dehmer, Patricia M. ^[2]; Dehmer, Joseph L. ^[2]; Ueda, K. ^[3]; West, J. B. ^[3]; Siggel, M. R.F. ^[3]; Hayes, M. A. ^[3]

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1. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)
3. Daresbury (United Kingdom). Daresbury Lab.

The spin--orbit selectivity of angle-resolved photoelectron spectra was used to provide new information on the electronic structure, symmetry, and decay dynamics of members of the autoionizing Tanaka--Ogawa Rydberg series in CO₂. This represents the first time that spin--orbit selectivity has been used to obtain such information for a polyatomic molecule. The spin--orbit photoelectron branching ratios were used to show that the angular momentum quantum number λ of the excited Rydberg electron does not change upon autoionization. Furthermore, a consideration of the present results together with previous calculations of the relative intensities of the discrete and continuum ionization channels shows that the most probable electron configuration for the Tanaka--Ogawa Rydberg series is ...(π_u)³(π_g)⁴ndδ_g and that autoionization proceeds primarily via a dδ_g→ϵfδ_u process for the totally symmetric vibronic components of the ion. The asymmetry parameter β was determined for individual spin--orbit components of the various vibronic bands of the X ²Π_g state and is discussed in terms of recent theoretical calculations. The Rydberg series appears to be well described by Ω_cω coupling, even for relatively low principal quantum numbers. The general utility of this technique for autoionizing Rydberg states and its extension to multiphoton ionization of Rydberg states that lie below the first ionization threshold are discussed.

• 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); Science and Research council (U.K)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7307535
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Vol. 100:12; 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-)
664400 -- Experimentally Derived Information on Atomic & Molecular Properties-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ASYMMETRY COEFFICIENTS
AUTOIONIZATION
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COUPLING
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
INTERMEDIATE COUPLING
IONIZATION
L-S COUPLING
LIFETIME
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
RYDBERG STATES
SPECTROSCOPY
SYMMETRY