Ionizing collisions of He( n sup 1 P ) atoms in a low-Rydberg state with SF sub 6 and NO sub 2 electron-attaching molecules

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Physical Review, A (General Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevA.42.273· OSTI ID:6416183

Pesnelle, A; Ronge, C; Perdrix, M; Watel, G ^[1]

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1. Service de Physique des Atomes et des Surfaces, Centre d'Etudes Nucleaires de Saclay, 91191 Gif-sur-Yvette CEDEX (France)

The ionization of He atoms, prepared in a well-defined ({ital n}=14) {sup 1}{ital P} Rydberg state, in collisions with electron-attaching molecules like SF{sub 6} and NO{sub 2}, is studied in a crossed-beam experiment at thermal energies. The ionization cross section is observed to be large for SF{sub 6}, reaching 4.2{times}10{sup {minus}13} cm{sup 2}, and to be smaller for NO{sub 2}, close to 10{sup {minus}15} cm{sup 2}. The dependence of these two cross sections on the relative velocity of the reactants exhibits a characteristic behavior with a saturation at low velocities, a dependence that is completely different from that obtained with polar molecules. The observation of such a dependence for NO{sub 2} indicates that, for this molecule, the reaction product is an ion pair, as for SF{sub 6}, and that ionization is not due to rotational energy transfer even though NO{sub 2} has a dipole moment. This dependence cannot be explained by the free-electron model'' usually used in Rydberg-atom--molecule collisions; it clearly shows that the interaction of the molecule with the ion core cannot be neglected.

• OSTI ID: 6416183
• Journal Information: Physical Review, A (General Physics); (USA), Journal Name: Physical Review, A (General Physics); (USA) Vol. 42:1; ISSN PLRAA; ISSN 0556-2791
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
BEAM DYNAMICS
BEAM-BEAM INTERACTIONS
CHALCOGENIDES
COLLISIONS
ELECTRONEGATIVITY
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GASES
HALIDES
HALOGEN COMPOUNDS
HELIUM
ION PAIRS
IONIZATION
MOLECULE COLLISIONS
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RARE GASES
RYDBERG STATES
SULFUR COMPOUNDS
SULFUR FLUORIDES