This is my doctoral thesis, written between 1998 and 2002 under the supervision of Professor Mark Child at the University of Oxford. Any of its shortcomings are entirely my own.
A simple theory relating the dynamics of [Rydberg] electrons to the long-range properties of the [Rydberg] molecular ionic core is developed for asymmetric top molecules in general and water in particular.
It is combined with the molecular version of multichannel quantum defect theory developed by Fano and Jungen and applied to the resonance-enhanced multiphoton ionization spectra of Child and Glab [DOI: 10.1063/1.480526], the mass-analysed threshold ionization spectra of Dickinson et al. [DOI: 10.1039/b005717g] and the as-yet  unpublished work of Glab [and Pratt, DOI: 10.1063/1.1701718] on the photoelectron branching ratios of the nd and nf Rydberg lines of the [ultraviolet spectrum of the] water molecule.
The effect of resonances between electronic and rotational motion in Rydberg molecules is investigated using multichannel quantum defect theory with special reference to the time-resolved wave packet experiments of Smith et al. [DOI: 10.1039/a909794e]
Rydberg states of atoms and molecules take their name from Johannes Rydberg of Halmstad, (scientist, 1854 to 1919, biography presented online by the University of St Andrews), not Viktor Rydberg of Jönköping (writer, 1828 to 1895).