Multiphoton ionization of atomic cesium
We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures.
- Research Organization:
- Oak Ridge National Lab., TN (USA); Georgia Univ., Athens (USA). Dept. of Physics
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6496277
- Report Number(s):
- CONF-840387-13; ON: DE85001266
- Resource Relation:
- Conference: 2. topical meeting on laser techniques in the extreme ultraviolet, Boulder, CO, USA, 5 Mar 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CESIUM
PHOTOIONIZATION
ANGULAR DISTRIBUTION
ATOMIC BEAMS
COLLIDING BEAMS
ELECTRIC FIELDS
EXCITATION
HYPERFINE STRUCTURE
LASER RADIATION
MULTI-PHOTON PROCESSES
ALKALI METALS
BEAMS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
IONIZATION
METALS
RADIATIONS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena