Resonant multiphoton ionization spectra of molecules and molecular fragments. Annual technical report, October 1987--September 1988

Technical Report · Sat Dec 31 04:00:00 EST 1988

DOI:https://doi.org/10.2172/656811· OSTI ID:656811

The objective of the research under this contract is to carry out studies of resonant enhanced multiphoton ionization (REMPI) processes in molecules. In the (n+1)-REMPI process of interest an atom or molecule in a specific initial state absorbs n photons making a transition to an intermediate state from which it is subsequently ionized by absorption of an additional photon. The studies are designed to provide a quantitatively robust analysis and prediction of key spectral features in several ongoing experimental studies and potentially practical applications of this technique. The specific problems of interest to the authors in these studied are (1) the vibrational distributions of ions that can be expected in REMPI of small molecules and molecular fragments with particular emphasis on their non-Franck-Condon behavior. Such non-Franck-Condon behavior introduces serious complications in the use of the technique for state-specific production of ions, e.g., O{sub 2}{sup +}({nu}) and OH{sup +}({nu}), and in the extraction of state populations from REMPI signals, (2) rotational distributions of ions that can be produced in various REMPI schemes and how these distributions can be tuned by choice of the resonant state and influenced by the molecular character of the photoelectron, and (3) the circular dichroism in photoelectron angular distributions, i.e., the difference in photoelectron angular distributions produced by right- and left-circularly polarized, and their use as a probe of molecular alignment. Here the author will summarize the progress that has been made to date in the studies of these features and applications of REMPI of molecules and molecular fragments. A significant feature of these studies, which will be explicitly assumed throughout the discussion below, is that they are carried out using quantitatively reliable molecular photoelectron orbitals.

• Research Organization: California Inst. of Tech., Pasadena, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: FG03-87ER60513
• OSTI ID: 656811
• Report Number(s): DOE/ER/60513--T10; ON: DE98006381; BR: HA0204030; KP0102000
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
EXCITED STATES
FRANCK-CONDON PRINCIPLE
LASER RADIATION
MOLECULES
MULTI-PHOTON PROCESSES
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
PROGRESS REPORT