Photoionization of excited molecular states

Conference · Sat Dec 31 23:00:00 EST 1983

OSTI ID:6570447

Dehmer, Patricia M.; Dehmer, Joseph L.; Pratt, Stephen T.

Rapid advances in laser and detector technologies are making it possible to investigate molecular photophysics and photochemistry in powerful new ways. For example, resonantly enhanced multiphoton ionization (REMPI) measurements, in which the total (or the mass selected) ion current is monitored as a function of laser wavelength, have yielded extensive and often novel information on the spectroscopy of the resonant intermediate states. With the addition of photoelectron spectrometry (PES) to analyze the kinetic energy of the ejected electrons, it is possible to determine the branching ratios into different electronic, vibrational, and rotational levels of the product ion and to focus directly on both the dynamics of the multiphoton ionization process and the photoionization of excited state species. In the present paper, we report several REMPI/PES studies of H₂ and N₂. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon behavior are observed, which reflect the more subtle dynamics of excited state photoionization.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6570447
• Report Number(s): CONF-8409129--1; ON: DE84017454
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
CHEMISTRY
CORRECTIONS
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
EXCITED STATES
HYDROGEN
IONIZATION
MOLECULES
MULTI-PHOTON PROCESSES
NITROGEN
NONMETALS
PHOTOCHEMISTRY
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
ROTATIONAL STATES
RYDBERG CORRECTION
SPECTROSCOPY
VIBRATIONAL STATES