LASER SPECTROSCOPY OF THE RYDBERG STATES OF $H^{\ast}_{3}$
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Date
1990
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
One-photon and two-photon excitation from the metastable $N = 0 \bar{B} 2p A_{2}^{-}$ state of $H_{3}$ are used to investigate the np, nd, and nf Rydberg series converging to the $N^{+}=1$ and $N^{+} = 3$ states of $H_{3}^{+}$. The excitation event is detected by monitoring $H_{3}^{+}$ ions formed by field-ionization, forced autoionization, and rotational autoionization. The nd and nf Rydberg states are well described by Hund'case (d) since the quantum defects are quite small. On the other hand, the two $N = 2$ members of the np Rydberg series show strong mixing [or intermediate coupling between Hund's cases (b) and (d) that is well described by MQDT using quantum defects $\mu_{0}= 0.009$ and $\mu_{1} \simeq 0.4$. The np and nd Rydberg series both show ``giant'' windows (or unexpectedly reduced intensity extending over several n values) near $n = 44$, and narrower windows at $n = 61$. The intensities of the lines in these windows are very sensitive to external electric fields $(\sim 0.1 V/cm)$ in the excitation region. Detailed studies now underway should allow the identification of the perturbing level and interaction mechanism responsible for these intensity variations.
Description
$^{\ast}$ Research supported by AFOSR and NSF
Author Institution: Molecular Physics Laboratory, SRI International; TRW, I Space Park
Author Institution: Molecular Physics Laboratory, SRI International; TRW, I Space Park