Collisional ionization between fast alkali atoms and selected hexafluoride molecules

Journal Article · Wed Mar 01 04:00:00 EST 1978 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.436024· OSTI ID:5168089

Compton, R N; Reinhardt, P W; Cooper, C D

Negative ion products resulting from collisions between orthogonal, crossed beams of alkali metal atoms (Na, K, Cs), and the octahedral hexafluorides MF/sub 6/ (M=S, Se, Te, Mo, W, Re, Ir, and Pt) have been examined in the energy range from approx.0 to 40 eV (lab). Studies of the dependence of the reaction thresholds upon the temperature of the target molecules SF/sub 6/, SeF/sub 6/, and TeF/sub 6/ have provided electron affinities for these molecules; E.A.(SF/sub 6/) =0.46 +- 0.2, E.A.(SeF/sub 6/) =2.9 +- 0.2, and E.A.(TeF/sub 6/) =3.3 +- 0.2 eV. Energy loss measurements of the alkali, A, in the reaction A+MF/sub 6/..-->..A/sup +/+MF/sup -//sub 6/ at small scattering angles are consistent with these values. Measurements for SF/sub 4/ together with temperature dependent thresholds for the formation of SF/sup -//sub 5/ from SF/sub 6/ and SF/sup -//sub 3/ from SF/sub 4/ combined with known bond dissociation energies for D(SF/sub 5/-F) and D(SF/sub 3/-F) yield electron affinity values for the SF/sub n/ series; E.A.(SF/sub 6/) =0.46 +- 0.2, E.A.(SF/sub 5/) =2.71 +- 0.2, E.A.(SF/sub 4/) =0.78 +- 0.2, and E.A.(SF/sub 3/) =3.07 +- 0.2 eV. Lower limits of approx.5 eV for the electron affinities of MoF/sub 6/, WF/sub 6/, ReF/sub 6/, IrF/sub 6/, and PtF/sub 6/ are implied by the detection of MF/sup -//sub 6/ ions when only the thermal (Tapprox.100 to 300 /sup 0/C) alkali beam (atoms plus dimers) is incident on MF/sub 6/. The cross sections for charge transfer A+MF/sub 6/..-->..A/sup +/+MF/sup -//sub 6/ are large at low energies which raises a question as to the mechanism of charge transfer since the zeroth order ground state covalent and ionic curves can never cross.

• Research Organization: Chemical Physics Section, Health and Safety Research Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• OSTI ID: 5168089
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 68:5; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AFFINITY
ALKALI METALS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CESIUM
COLLISIONS
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
EV RANGE
EV RANGE 01-10
EV RANGE 10-100
FERMIONS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
IONIZATION
LEPTONS
METALS
MOLECULE COLLISIONS
POTASSIUM
SELENIUM COMPOUNDS
SELENIUM FLUORIDES
SODIUM
SULFUR COMPOUNDS
SULFUR FLUORIDES
TELLURIUM COMPOUNDS
TELLURIUM FLUORIDES
TELLURIUM HALIDES