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Vibrational Branching Ratios and Asymmetry Parameters in the Photoionization of CO 2 in the Region Between 650 Å and 840 Å

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ABSTRACT

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.

No MeSH data available.


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Three dimensional plot of the results of the fitting routine for all the spectra measured. The molecular energy axis represents the vibrational excitation of the ionic ground state of . The plot dramatically shows the increased vibrational excitation caused by autoionization phenomena.
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f5-j65par: Three dimensional plot of the results of the fitting routine for all the spectra measured. The molecular energy axis represents the vibrational excitation of the ionic ground state of . The plot dramatically shows the increased vibrational excitation caused by autoionization phenomena.

Mentions: The three dimensional plot shown in Fig. 5 shows the electron spectra where the most intense members have been truncated in order to reveal the detail in the higher vibrational modes. Examination of this figure reveals the amount of vibrational excitation occurring as a result of autoionization which populate molecular energy levels well above 0.5 eV. This excess population of excited state would have consequences on the reactivity of this molecule in atmospheres where is formed by uv irradiation. When the number of electrons as a function of molecular energy are summed as shown in Fig. 5, the total electron count as shown in Fig. 4 is obtained.


Vibrational Branching Ratios and Asymmetry Parameters in the Photoionization of CO 2 in the Region Between 650 Å and 840 Å
Three dimensional plot of the results of the fitting routine for all the spectra measured. The molecular energy axis represents the vibrational excitation of the ionic ground state of . The plot dramatically shows the increased vibrational excitation caused by autoionization phenomena.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862820&req=5

f5-j65par: Three dimensional plot of the results of the fitting routine for all the spectra measured. The molecular energy axis represents the vibrational excitation of the ionic ground state of . The plot dramatically shows the increased vibrational excitation caused by autoionization phenomena.
Mentions: The three dimensional plot shown in Fig. 5 shows the electron spectra where the most intense members have been truncated in order to reveal the detail in the higher vibrational modes. Examination of this figure reveals the amount of vibrational excitation occurring as a result of autoionization which populate molecular energy levels well above 0.5 eV. This excess population of excited state would have consequences on the reactivity of this molecule in atmospheres where is formed by uv irradiation. When the number of electrons as a function of molecular energy are summed as shown in Fig. 5, the total electron count as shown in Fig. 4 is obtained.

View Article: PubMed Central - PubMed

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus