Gas-phase vibrational spectroscopy of the dysprosium monoxide molecule and its cation.

ABSTRACT

Rotationally resolved vibrational spectra of DyO and DyO+ in a molecular beam are obtained by IR excitation from the X8 ground state and from high-n Rydberg states of DyO using an infrared free electron laser. Vibrational excitation is detected either by resonance enhanced multiphoton ionisation from X8(v = 1) or by autoionisation of Rydberg states converging to DyO+(v = 1). For most heavy molecules, the large spectral width of an infrared free electron laser does not allow for rotational resolution. In DyO and DyO+ the P, Q, and R transitions can be resolved due to the high angular momentum in their ground states. For 164DyO a vibrational constant of ωe = 847.5(2) cm-1 and a vibrational anharmonicity of ωeχe = 2.9(1) cm-1 are deduced. For the 161DyO+ cation a transition frequency of ΔG1/2 = 907(1) cm-1 is found.