Predissociation of Rydberg states of CO investigated by the detection of atomic fragments

摘要

Predissociation of Rydberg states of CO has been investigated by the C (3P and ‘D) and 0(P) photofragment measurements in the region of 103 000—114000 cm’ (88—97 nm). The simulations of the rotational structures of np and nf Rydberg states were also carried out by using the i-uncoupling Hamiltonian model. The photofragment yield spectra were compared with the ion-dip spectra which correspond to the absorption spectra, indicating that all the Rydberg states, ns, np, nd, and nf converging to the x 2~ + CO~ ion, were subject to the predissociation. It was found that the lower member np ~ and nd’rr states exhibit two dissociation path ways, that is the COP) ±0(P) and the C(1D)±O(3P) channels. Especially, for the 4prrL 1I1(v~0) state the two channels were found to be competitive with respect to parity as well as rotational quantum number J. At higher np series, such a parity and f-dependence of the predissociation disappeared, and the observed rotational structure was simulated very well by the model with no parity nor J dependence. For the ndo- states, the spectra of the 3du and Sdu(v 0) states were diffuse, while the 4dcr(v0)state showed a rotationally resolved photofragment yield spectrum. All the photofragment yield spectra of the nf(v 0) states exhibited sharp structures compared with those of other Rydberg states with a small 1 value. From a comparison between the photofragment yield spectrum and the ion-dip spectrum, it was found that the predissociation rate of the e-symmetry component is larger than that of the f symmetry component. It was suggested that the e-symmetry levels predissociate through D’ ~ + valence states, while thef symmetry levels predissociate through the 2 1fl state.