High-resolution overtone spectra of molecular complexes

A high-resolution spectrum of the acetylenewater complex has been recorded in the overtone range. Two bands of C2H2D2O were analysed, corresponding to the overtone excitations of either the acetylene or the water units. The vibrational shifts and the upper states rotational constants were retrieved, demonstrating that the geometry of the complex is only slightly modified by the excitation. A larger linewidth was observed for the 2CH band than for the 2OD+DOD band, probably due to the direct coupling of the 2CH excitation with the dissociation coordinate.