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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.


Related in: MedlinePlus

Histogram of the calculated Franck-Condon factors for the  ground state at positions in the absorption spectrum where Rydberg autoionizing resonance levels exist. The calculation could not distinguish between the various members of a particular series and hence the same distribution is attributed irrespective of principal quantum number. The resonances calculated are for the Tanaka-Ogawa series with vibrational levels of 0,1,2,3 quanta of the symmetric stretch in the ground electronic state of .
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f22-j65par: Histogram of the calculated Franck-Condon factors for the ground state at positions in the absorption spectrum where Rydberg autoionizing resonance levels exist. The calculation could not distinguish between the various members of a particular series and hence the same distribution is attributed irrespective of principal quantum number. The resonances calculated are for the Tanaka-Ogawa series with vibrational levels of 0,1,2,3 quanta of the symmetric stretch in the ground electronic state of .

Mentions: The results are shown in Fig. 21 as a bar chart, where each group of intensities corresponds to the resonance shown. The heights of the bars correspond to the branching ratios for (0,0,0) to (7,0,0), going from left to right in each group, with the additional contributions added as described above. In Fig. 22, the theoretical values from the previous work are shown. In principle these should be the same for any given Rydberg series, and are labelled accordingly. Some similarities are immediately obvious:


Vibrational Branching Ratios and Asymmetry Parameters in the Photoionization of CO 2 in the Region Between 650 Å and 840 Å
Histogram of the calculated Franck-Condon factors for the  ground state at positions in the absorption spectrum where Rydberg autoionizing resonance levels exist. The calculation could not distinguish between the various members of a particular series and hence the same distribution is attributed irrespective of principal quantum number. The resonances calculated are for the Tanaka-Ogawa series with vibrational levels of 0,1,2,3 quanta of the symmetric stretch in the ground electronic state of .
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f22-j65par: Histogram of the calculated Franck-Condon factors for the ground state at positions in the absorption spectrum where Rydberg autoionizing resonance levels exist. The calculation could not distinguish between the various members of a particular series and hence the same distribution is attributed irrespective of principal quantum number. The resonances calculated are for the Tanaka-Ogawa series with vibrational levels of 0,1,2,3 quanta of the symmetric stretch in the ground electronic state of .
Mentions: The results are shown in Fig. 21 as a bar chart, where each group of intensities corresponds to the resonance shown. The heights of the bars correspond to the branching ratios for (0,0,0) to (7,0,0), going from left to right in each group, with the additional contributions added as described above. In Fig. 22, the theoretical values from the previous work are shown. In principle these should be the same for any given Rydberg series, and are labelled accordingly. Some similarities are immediately obvious:

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