Autoionizing np Rydberg states of H/sub 2/

Journal Article · Sat Apr 15 04:00:00 EDT 1989 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.39.3979· OSTI ID:6315427

Xu, E Y; Helm, H; Kachru, R

We report a study of the autoionizing np Rydberg states near the lowest ionization threshold of H/sub 2/. Using resonant two-photon excitation, intermediate states in specific rotovibrational levels in the double well, E,F /sup 1/..sigma../sub g//sup +/ states are prepared. Then, a second, tunable laser is used to photoionize via excitation of the np Rydberg states. Because of the stepwise laser excitation scheme employed in our experiment the photoionization occurs from states with vibrational wave functions very similar to those of the H/sub 2//sup +/ core. As a consequence, the autoionizing states appear as nearly symmetric resonances, rather than the highly asymmetric Beutler-Fano profiles observed from the direct photoexcitation from the ground state of H/sub 2/. Our experiments show that the J = 1 np states are broader than the J = 3 np states converging to the same limit, suggesting that the two states autoionize into the epsilon-cp and epsilon-cf continuum, respectively. We compare our observations with a theoretical analysis using a multichannel quantum defect theory. The J = 1 states reveal the profound effect caused by the perturbation of the autoionizing Rydberg series converging to the lowest vibrational and rotational state of H/sub 2//sup +/ by low-n states converging to higher vibrational states of the H/sub 2/-ion core.

• Research Organization: Molecular Physics Laboratory, SRI International, Menlo Park, California 94025
• OSTI ID: 6315427
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 39:8; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
AUTOIONIZATION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
HYDROGEN
IONIZATION
LASER RADIATION
LEVEL WIDTHS
MOLECULES
NONMETALS
OPTICAL PUMPING
PROBES
PUMPING
RADIATIONS
RESONANCE
RYDBERG STATES