Time dependences of two-, three-, and four-photon ionization of atomic hydrogen in the ground 1 /sup 2/S and metastable 2 /sup 2/S states
The two-level model of multiphoton ionization is reviewed within the context of an exact theoretical framework. Parametrization of the complex dressed states arising in a generalized Floquet analysis gives numerical values for the effective two-level parameters for two-, three-, and four-photon ionization of ground-state atomic hydrogen with the (m/sub l/ = 0) intermediate resonant states 2p, 2s, and 3p, respectively. Detailed time dependences of the ionization process are given for responses to a linearly polarized, monochromatic, single-mode laser turned on suddenly with respect to near-resonant states, but adiabatically with respect to all others. Appropriate expressions for time-independent ionization rates are obtained during specific time intervals. The K index (K = partial lnN/partial lnI), of interest in recent experiments, is understood within the framework of a simple model. Application to four-photon ionization of the metastable /sup 2/S/sub 1/2/ state of hydrogen illustrates the breakdown of the two-level model, as the number of ''near-resonant'' levels is a function of the field strength.
- Research Organization:
- Department of Physics, University of Colorado, Boulder, Colorado 80309
- OSTI ID:
- 5960387
- Journal Information:
- Phys. Rev. A; (United States), Vol. 27:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROGEN
PHOTOIONIZATION
FLOQUET FUNCTION
FLUX DENSITY
GROUND STATES
LASER RADIATION
METASTABLE STATES
MULTI-PHOTON PROCESSES
PHOTON-ATOM COLLISIONS
TIME DEPENDENCE
ATOM COLLISIONS
COLLISIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
IONIZATION
NONMETALS
PHOTON COLLISIONS
RADIATIONS
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory