Investigations of the potential functions of weakly bound diatomic molecules and laser-assisted excitive Penning ionization

Technical Report · Sat May 01 00:00:00 EDT 1982

DOI:https://doi.org/10.2172/5167167· OSTI ID:5167167

Goble, Jr, J H

Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5167167
• Report Number(s): LBL-14278; ON: DE82017259; TRN: 82-016861
• Resource Relation: Other Information: Thesis. Includes 3 sheets of 48x reduction microfiche. Portions of document are illegible
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
MOLECULAR IONS
BINDING ENERGY
POTENTIALS
MOLECULAR MODELS
MOLECULES
PENNING EFFECT
ARGON
BERYLLIUM
COVALENCE
DIMERS
DISSOCIATION
EXCITED STATES
HELIUM
IONIZATION
METASTABLE STATES
NEON
SODIUM
VIBRATIONAL STATES
ALKALI METALS
ALKALINE EARTH METALS
CHARGED PARTICLES
ELEMENTS
ENERGY
ENERGY LEVELS
FLUIDS
GASES
IONS
MATHEMATICAL MODELS
METALS
NONMETALS
RARE GASES
640305* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Theory- (-1987)