Multichannel quantum defect analysis of the double resonance photoionization series of H2O

A new analysis is presented of the recent photoionization spectrum of H2O, excited by double resonance via several rotational sublevels of the (100) v ibrational level of the C(B-1(1)) state. Evidence for a previously unsuspec ted strong f series indicates significant d orbital contamination of the no minal p orbital in the intermediate state. This is the first report of an f series in the Rydberg state of any asymmetric top. Previous d series analy ses of single-photon photoionization spectra terminating on the (100) level of H2O+ are also corrected and extended to a wider range of excited rotati onal electronic states. The d series appears to contain absent lines, indic ative of predissociation. Some lines remain unassigned, but there is no sys tematic evidence of either s or p series. (C) 2000 American Institute of Ph ysics. [S0021-9606(00)01408-2].