Triatomic Hydrogen
Welcome to the Triatomic Hydrogen Group at the Department of Molecular and Optical Physics - University of Freiburg, Germany

Ab initio analysis of autoionization of H3 molecules using multichannel quantum defect theory and new quantum defect surfaces
I. Mistrík1, R. Reichle1, U. Müller1, H. Helm1, M. Jungen2 and J. A. Stephens3
1Department of Molecular and Optical Physics, Albert-Ludwigs-Universität, Hermann-Herder-Strasse 3, D-79104  Freiburg, Germany
2Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
3Nuclear Data Section, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, P.O. Box 100, Wagramer Strasse 5, A-1400 Vienna, Austria

Highly accurate Born-Oppenheimer potential-energy surfaces of H3 were calculated and combined with multichannel quantum-defect theory (MQDT) to predict with high precision the photoionization cross section of laser-excited triatomic hydrogen recently measured in this laboratory. The experiment first prepares H 3 in stepwise excitation in a single rotational level of the symmetric stretch excited 3s Rydberg state. One-photon ionization from this state populates the continuum and np Rydberg states which autoionize into H3 + + e-. In the vicinity of the first symmetric stretch excited level of H3+ the ionization spectrum shows features similar to those observed at the lowest ionization threshold: a quasidiscrete region below the first symmetric-stretch excited threshold, a Beutler-Fano region of rotational autoionization and interlopers of low-n Rydberg states belonging to high vibrationally excited cores dispersed over the continuum. The MQDT calculations include rotational, vibrational, and Jahn-Teller interactions, and permit the assignment of most of the spectral features. ©2000 The American Physical Society

©2000 Physical Review A 61, 033410 (2000)

DOI: 10.1103/PhysRevA.61.033410
PACS number~s!: 33.80.Rv, 33.80.Eh

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