S AND D RYDBERG SERIES OF NO PROBED BY DOUBLE-RESONANCE MULTIPHOTON IONIZATION - MULTICHANNEL QUANTUM DEFECT ANALYSIS

The s and d Rydberg States of NO with v = 0 hâve been observed for 6 ≤n*≤40 by double resonance multiphoton ionization which was three- photon resonant with the 3pπC2∏ (ʋ = 0) Rydberg intermediate state. Strong parity selection is shown to occur in thè intermediate level despite the fact that the ∆-doublets are not resolved. The OODR spectra are thereby considerably simplified. A unified description of the rotational-electronic structure of the s and d Rydberg States in terms of quantum defect theory is presented, extending from the low n* s, d supercomplexes up beyond the ionization threshold. Electronic radial dipole transition moments are calcu- lated and included in the MQDT analysis, giving evidence for a Cooper minimum in the region of the supercomplex n* = 5. For 25 ≤ n* ≤ 40 fringes are observed in the OODR spectrum and are interpreted in terms of rotational Ɩ-uncoupling, electronic s - d mixing and energy dependent elec- tronic dipole transition moments. The fringe formation is shown to have a different origin than the stroboscopie effect observed in Na2 by Labastie et al. Above n* = 35 the Stark induced p series appears and is also interpreted quantitatively. © 1987 Taylor & Francis Group, LLC.