Multichannel quantum defect theory simulations of the Rydberg spectra of HCO

Multi-channel quantum defect theory (MQDT) is used to simulate the photoionization spectrum of HCO involving autoionizing Rydberg states converging on the v+2 = 1, 2 and 3 thresholds. The simulations are compared with experimentally recorded spectra of resonances converging to the (0310) state of HCO+ observed from the photoselected 3pπ 2Π (030) K' = 0, N' = 0 intermediate state, and with spectra converging to the lower thresholds obtained by Mayer and co-workers. Matrix elements off-diagonal in l and v+2 are included to account for all channel interactions and autoionization. A reasonable agreement between experiment and theory is obtained by optimization of both the diagonal and off-diagonal elements of the quantum defect matrix, which are found to vary with the vibrational quantum number. © 2005 Taylor and Francis Group Ltd