Nonperturbative treatments of level shifts of excited states and high-order harmonic generation in strong fields

Journal Article · Sun Apr 01 00:00:00 EST 1990 · Journal of the Optical Society of America, Part B: Optical Physics; (USA)

DOI:https://doi.org/10.1364/JOSAB.7.000425· OSTI ID:7134937

Chu, S; Wang, K; Layton, E ^[1]

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1. Department of Chemistry, University of Kansas, Lawrence, Kansas 66045 (USA)

In this paper we accomplish three goals. First, we present new nonperturbative results of complex quasi-energies (shifts and widths) for several low-lying excited states of atomic H in strong fields, using the {ital L}{sup 2} non-Hermitian Floquet matrix technique. Second, we present a new nonperturbative {ital L}{sup 2} technique for the treatment of ac Stark shifts of arbitrary excited states. We found that all the Rydberg states in weak fields are upshifted and closely follow the quadratic field dependence described by the ponderomotive potential {ital e}{sup 2}{ital F}{sup 2}/4{ital mgw}{sup 2}. Large deviation from the ponderomotive shift and intricate level-shift behaviors, however, occur in strong fields. Finally, we present a classical nonperturbative treatment of the electronic motion in intense laser fields. We show that the spectral analysis of classical trajectories can provide detailed insights regarding the mechanisms responsible for the multiple-harmonic generation recently observed in high-intensity experiments.

• OSTI ID: 7134937
• Journal Information: Journal of the Optical Society of America, Part B: Optical Physics; (USA), Vol. 7:4; ISSN 0740-3224
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
HYDROGEN
MULTI-PHOTON PROCESSES
QUANTUM ELECTRONICS
ELECTROMAGNETIC FIELDS
EXCITED STATES
HARMONIC GENERATION
LASER RADIATION
RYDBERG STATES
SPECTRAL SHIFT
STARK EFFECT
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
FREQUENCY MIXING
NONMETALS
RADIATIONS
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory