Vibrational Branching Ratios and Asymmetry Parameters in the Photoionization of CO₂ in the Region Between 650 Å and 840 Å

Journal Article · Sat Sep 01 00:00:00 EDT 2001 · Journal of Research of the National Institute of Standards and Technology

DOI:https://doi.org/10.6028/jres.106.038· OSTI ID:1904060

Parr, A. C. ^[1]; West, J. B. ^[2]; King, M. R. F. ^[2]; Ueda, K. ^[3]; Dehmer, P. M. ^[4]; Dehmer, J. L. ^[5]

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1. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); OSTI
2. Science and Technology Facilities Council (STFC), Warrington (United Kingdom). Daresbury Lab.
3. Tohoku Univ., Sendai (Japan)
4. US Department of Energy (USDOE), Germantown, MD (United States). Office of Science, Basic Energy Sciences (BES)
5. National Science Foundation (NSF), Arlington, VA (United States)

The vibrational branching ratios and asymmetry parameters for CO₂ have been determined in the wavelength region of 650 Å to near the ionization onset at about 840 Å. The study was performed using synchrotron radiation from the Daresbury storage ring that was dispersed with a 5 m grating monochomator that afforded resolution of 0.1 Å to 0.2 Å. This resolution allowed the study of the branching ratios and asymmetry parameters with enough detail to see the changes in the parameters within the pronounced autoionization structure in CO₂ in this wavelength region. While the electron spectrometer resolution was not sufficient to resolve the spin orbit and Renner-Teller splitting in the photoelectron spectra, we are able to fit the data with a model that identifies the major structure in terms of the symmetric stretch and elements of the asymmetric stretch and bending modes. A calculation of the expected relative vibrational excitations based upon the Franck-Condon principle clearly showed non-Franck-Condon behavior in some of the vibrational-electronic transitions.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Basic Energy Sciences (BES)
• Sponsoring Organization: USDOE
• OSTI ID: 1904060
• Journal Information: Journal of Research of the National Institute of Standards and Technology, Journal Name: Journal of Research of the National Institute of Standards and Technology Journal Issue: 5 Vol. 106; ISSN 1044-677X
• Publisher: National Institute of Standards (NIST)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
asymmetry
autoionization
branching ratios
parameters
photoelectron spectra