Collisional coherent excitation to the n=2 state of hydrogen

Journal Article · Fri Aug 01 04:00:00 EDT 1980 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.22.473· OSTI ID:5208326

Krotkov, R; Stone, J

This paper presents measurements of the Lyman-..cap alpha.. photons emitted when target gases He, Ar, O/sub 2/, and N/sub 2/ are bombarded by a beam of ground-state hydrogen atoms. The collisions take place in the presence of an axial electric field and the observed Lyman-..cap alpha.. brightness depends on field direction. This observation is interpreted as evidence for excitation of hydrogen atoms to states which are linear superpositions of 2s and 2p. Measurements are presented of a ''mixed'' cross section sigma/sub s/p which characterizes the degree of coherent excitation. The real part of sigma/sub s/p measures the electric dipole moment created by the collision, while the imaginary part measures the rate at which the moment is changing. It is found that these quantities vary substantially over the energy range 3--30 keV, with maximal values being about as large as permitted theoretically. Coherent excitation should be present to some degree in all inelastic collisions and, when measurable, provides new tests of scattering theory. Some implications are also discussed for precision frequency measurements and searches for weak-interaction effects in atomic physics.

• Research Organization: Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003
• OSTI ID: 5208326
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 22:2; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
ATOMIC BEAMS
BEAMS
COLLISIONS
CRYOGENIC FLUIDS
ELECTRIC FIELDS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUIDS
HELIUM
HYDROGEN
LYMAN LINES
MOLECULE COLLISIONS
NITROGEN
NONMETALS
OXYGEN
RARE GASES