Sub-Doppler rotationally resolved overtone spectroscopy of the HCN dimer

Abstract
A new molecular beam color center laser spectrometer, which can be tuned single mode under computer control around 1.5 μm, has been used to obtain the sub-Doppler, rotationally resolved, first overtone spectrum of the nonbonded C–H stretch vibration of the HCN dimer. As for the corresponding fundamental vibration, the linewidth is instrument limited, posing a minimum limit of 11 ns to the lifetime of the excited complex.