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



Albert C. Parr, J B. West, M R. King, K Ueda, P M. Dehmer, J L. Dehmer


The vibrational branching ratios and asymmetry parameters for CO2 have been determined in the wavelength region of 650 to near ionization onset at about 840 . 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 to 0.2 resolution. This resolution allowed the study of the branching ratios and asymmetry parameters with enough detail to see the changes in the parameters within the structure of the pronounced autoionization absorption 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 were 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 on the Franck-Condon principle clearly showed non Franck-Condon behavior in some of the vibrational-electronic transitions.
Journal of Research (NIST JRES) -
106 No. 5


asymmetry, autoionization, branching ratios, parameters, photoelectron spectra


Parr, A. , West, J. , King, M. , Ueda, K. , Dehmer, P. and Dehmer, J. (2001), Vibrational Branching Ratios and Asymmetry Parameters in the Photoionization of CO<sub>2</sub> in the Region Between 650 and 840, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 24, 2024)
Created October 1, 2001, Updated February 17, 2017