Calculation of a preconvolved HD photoionization spectrum using the rovibrational frame transformation

We apply a multichannel quantum defect approach to describe many of the exp erimentally observed peaks in the HD photoionization cross-section above th e ionization threshold. This method employs a rovibrational frame transform ation between the short- and long-range coupling representations to quantit atively predict the breakup into physical fragmentation channels in terms o f a small set of bound-state parameters that define a short-range scatterin g matrix. Using a preconvolution technique developed by Robicheaux, we enfo rce asymptotic boundary conditions in a way that replicates the effect of a finite experimental resolution. Our results quantitatively describe many c omplex resonant features observed by Dehmer and Chupka. Inconsistencies bet ween the theoretical and experimental spectra appear to mainly reflect our neglect of competing predissociation channels, as well as the breakdown of approximate g-u symmetry that occurs increasingly at large internuclear dis tances.