Vibrationally resolved band profiles for autoionisation of NO (c3Π) nlλ (vR=0) Rydberg states into NO+ A1Π (vi=0, 1, 2) vibronic levels

Excitation spectra for dispersed VUV-fluorescence of NO (λfl=134-152 nm) were measured in the exciting-photon energy range between 16.9 and 24.8 eV using monochromatised synchrotron radiation at medium bandwidth of 29 meV. Fluorescence from A1Π (vi=0, 1, 2) vibronic NO+-levels and fluorescence from excited dissociation fragments NI (3s 2PJ) was observed simultaneously by recording the dispersed fluorescence with a monochromator-position-sensitive detector combination. The autoionisation of NO (c3Π) nlλ (vR=0) Rydberg levels into the NO+ A1Π (vi=0, 1, 2) vibronic levels was observed vibrationally resolved. Different Beutler-Fano profiles for autoionisation of one Rydberg level NO (c3Π) nlλ (vR=0) into the different vibronic NO+ A1Π (vi=0, 1, 2) levels are clearly visible. The dependence of the Beutler-Fano profiles on the quantum numbers n, l, and λ of the Rydberg electron is discussed. For the direct photoionisation into the NO+ A1Π (vi=0, 1, 2) vibronic levels a non-Franck-Condon behaviour was observed