Effects of Shape Resonances on Vibrational Intensity Distributions in Molecular Photoionization

Abstract

We report striking non-Franck-Condon vibrational intensity distributions associated with the shape resonance in the 5cr photoionization channel of CO. This example confirms the recent theoretical prediction that shape resonances will couple significantly with vibrational motion, leading to different resonance energies and profiles, and non-Franck-Condon intensities in alternative vibrational channels. Analogous effects are expected in connection with the widespread occurrence of shape resonances in both innershell and outershell molecular photoionization spectra.

Vibrational branching ratios in the photoelectron spectra of N2 and CO: interference and diffraction effects

“…In particular, a wealth of experimental and theoretical data has been published for total cross sections corresponding to core as well as valence-shell photoionization of the prototype N 2 1-35 and CO 1,2,5,6,12,13,34,[36][37][38][39][40][41][42][43][44][45][46][47][48][49] molecules, from the ionization threshold up to a few tens of eV above it. More recently, the advent of high-brilliance 3rd-generation synchrotron radiation sources in combination with high energy-resolution detection techniques has opened the way for the determination of vibrationally resolved photoionization spectra of these molecules, both at low and high photon energies 30,35,38,39,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] . These experimental achievements have fostered the development of new theoretical methods that, in addition to accounting for electronic degrees of freedom, are also able to describe the molecule's vibrations 13,30,35,…”

Shape-Resonance-Enhanced Nuclear-Motion Effects in Molecular Photoionization

“…27 This work was performed under the auspices of the U. S. Department of Energy and National Science Foundation Grant No. CHE 78-08707.…”

Vibrationally resolved photoelectron angular distributions and branching ratios for the carbon dioxide molecule in the wavelength region 685–795 Å

“…The ␤ parameters and branching ratios were calculated from the measurements made at the two angles ϭ0°and ϭ90°. 16 We define the vibrational branching ratio as follows: The intensity going into a particular vibrational level of the ground state of the ion divided by the sum of the intensities of all the measured vibrational levels. The number of electrons detected within the constant solid angle of acceptance of the detection system and for an integrated photon flux is proportional to the differential cross section.…”