Highly resolved studies of vacuum ultraviolet photoionization dynamics

Thesis/Dissertation · Fri Dec 31 04:00:00 EST 1993

OSTI ID:98650

Kakar, S

The authors use measurements of dispersed fluorescence from electronically excited photoions to study fundamental aspects of intramolecular dynamics. Experimental innovations make it possible to obtain highly resolved photoionization data that offer qualitative insights into molecular scattering. In particular, they obtain vibrationally resolved data to probe coupling between the electronic and nuclear degrees of freedom by studying the distribution of vibrational energy among photoions. Vibrationally resolved branching ratios are measured over a broad spectral range of excitation energy and their non-Franck-Condon behavior is used as a tool to investigate two diverse aspects of shape resonant photoionization. First, vibrational branching ratios are obtained for the SiF{sub 4} 5a{sub 1}{sup {minus}1} and CS{sub 2} 5{sigma}{sub u}{sup {minus}1} photoionization channels to help elucidate the microscopic aspects of shape resonant wavefunction for polyatomic molecules. It is shown that in such molecules the shape resonant wavefunction is not necessarily attributable to a specific bond in the molecule. Second, the multichannel aspect of shape resonant photoionization dynamics, reflected in continuum channel coupling, is investigated by obtaining vibrational branching ratios for the 2{sigma}{sub u}{sup {minus}1} and 4{sigma}{sup {minus}1} photoionization of the isoelectronic molecules N{sub 2} and CO, respectively. These data indicate that effects of continuum coupling may be widespread. They also present the first set of {ital rotationally resolved data} over a wide energy range for the 2{sigma}{sub u}{sup {minus}1} photoionization of N{sub 2}. These data probe the partitioning of the angular momentum between the photoelectron and photoion, and highlight the multicenter nature of the molecular potential.

• Research Organization: Louisiana State Univ. and Agricultural and Mechanical Coll., Baton Rouge, LA (United States)
• OSTI ID: 98650
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
FLUORESCENCE
FRANCK-CONDON PRINCIPLE
IONS
MOLECULES
PHOTOIONIZATION
VIBRATIONAL STATES