Multiphoton ionization of atomic cesium

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6496277

Compton, R N; Klots, C E; Stockdale, J A.D.; Cooper, C D

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
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ANGULAR DISTRIBUTION
ATOMIC BEAMS
BEAMS
CESIUM
COLLIDING BEAMS
DISTRIBUTION
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
HYPERFINE STRUCTURE
IONIZATION
LASER RADIATION
METALS
MULTI-PHOTON PROCESSES
PHOTOIONIZATION
RADIATIONS