Electron-impact excitation of atoms in the presence of a nearly resonant laser field

Journal Article · Sat Mar 31 23:00:00 EST 1990 · Physical Review, A (General Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevA.41.3770· OSTI ID:7188535

Francken, P ^[1]; Joachain, C J ^[2]

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1. Physique Theorique, Faculte des Sciences, Code Postal 227, Universite Libre de Bruxelles, B-1050 Brussels, Belgium (BE)
2. Physique Theorique, Faculte des Sciences, Code Postal 227, Universite Libre de Bruxelles, B-1050 Brussels, Belgium (BE) Institut de Physique, Universite de Louvain, B-1348 Louvain-la-Neuve, Belgium (BE)

We have studied the electron-impact excitation of an atom, in the presence of a laser field whose photon energy is tuned close to the energy difference between two excited final states. Both the laser-projectile and the laser-target interactions are treated nonperturbatively, while the electron-atom interaction is treated within the first Born approximation. As an application, we have analyzed the resonant laser-assisted excitation of the 2{sup 1}{ital S} and 2{sup 1}{ital P} states of helium. The agreement between the present nonperturbative results and previous perturbative ones is excellent, except for very small detunings. The present nonperturbative treatment also shows that the results given by perturbation theory on both sides of the resonance, when plotted as a function of the laser frequency, correspond to the excitation of different Floquet pseudostates. This is related to the presence of avoided crossings in the diagram of the Floquet pseudoenergies, as a function of the laser frequency.

• OSTI ID: 7188535
• Journal Information: Physical Review, A (General Physics); (USA), Journal Name: Physical Review, A (General Physics); (USA) Vol. 41:7; 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
BORN APPROXIMATION
COLLISIONS
ELECTROMAGNETIC RADIATION
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUIDS
GASES
HELIUM
LASER RADIATION
NONMETALS
PERTURBATION THEORY
RADIATIONS
RARE GASES
RESONANCE