A Discussion on photoelectron spectroscopy - The role of autoionization in molecular photoelectron spectra

The Fano-Mies theory of configuration interaction is applied to the photoionization of diatomic molecules, yielding an expression which gives the relative intensity of vibrational peaks in photoelectron spectra when one or more autoionizing states are in the vicinity of the excitation energy. In some cases the vibrational intensity distribution depends only on Franck-Condon factors connecting autoionizing and final states. Illustrative calculations for O2 show the transition from this limit to the limit of direct photoionization as the line profile index decreases.

Distributions of calculated Franck-Condon factors for autoionizing transitions are used to illustrate the way in which the vibrational structure of the photoelectron spectrum may be extended in a characteristic manner when the wavelength of the exciting radiation coincides with a resonance in the photoionization cross section of a diatomic gas. The calculations are found to be in good agreement with resonance wavelength photoelectron spectra from O2.


Author(s):  
Jia-Lin Chang ◽  
Wen-Hsin Kuo ◽  
Yun-Jhu Huang ◽  
Mu-Fong Chang ◽  
Jui-Yang Huang ◽  
...  

2005 ◽  
Vol 04 (01) ◽  
pp. 225-245 ◽  
Author(s):  
IKUO TOKUE ◽  
KATSUYOSHI YAMASAKI ◽  
SATOSHI MINAMINO ◽  
SHINKOH NANBU

To elucidate the ionization dynamics, in particular the vibrational distribution, of H 2 O +(Ã) produced by photoionization and the Penning ionization of H 2 O and D 2 O with He *(2 3S) atoms, Franck–Condon factors (FCFs) were given for the [Formula: see text] ionization, and the transition probabilities were presented for the [Formula: see text] emission. The FCFs were obtained by quantum vibrational calculations using the three-dimensional potential energy surfaces (PESs) of [Formula: see text] and [Formula: see text] electronic states. The global PESs were determined by the multi-reference configuration interaction calculations with the Davidson correction and the interpolant moving least squares method combined with the Shepard interpolation. The obtained FCFs exhibit that the [Formula: see text] state primarily populates the vibrational ground state, as its equilibrium geometry is almost equal to that of [Formula: see text], while the bending mode (ν2) is strongly enhanced for the H 2 O +(Ã) state; the maximums in the population of H 2 O + and D 2 O + are approximately v2 = 11–12 and 15–17, respectively. These results are consistent with the distributions observed by photoelectron spectroscopy. Transition probabilities for the [Formula: see text] system of H 2 O + and D 2 O + show that the bending progressions consist primarily of the [Formula: see text] emission, with combination bands from the (1, v′2 = 4–8, 0) level being next most important.


1978 ◽  
Vol 82 (17) ◽  
pp. 1901-1907 ◽  
Author(s):  
Akira Namiki ◽  
Nobuaki Nakashima ◽  
Keitaro Yoshihara ◽  
Yoshiro Ito ◽  
Takenobu Higashimura

1993 ◽  
Vol 71 (10) ◽  
pp. 1622-1626 ◽  
Author(s):  
Walter J. Balfour ◽  
Belvai J. Shetty

A new group of bands has been observed in emission in the 500–600 nm region under conditions that generate known systems of GeS. It has been deduced from the appearance and position of the bands, and from their intensity distribution, that these bands constitute the long-wavelength component of the E1Σ+–X1Σ+ system of GeS, which gives rise to strong absorption and emission in the ultraviolet. E–X Franck–Condon factors have been estimated.


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