Rotational analysis and vibrational predissociation in the ν2 band of HCN dimer

The rovibrational infrared spectrum of the bound C–H stretching vibration, ν2, in the HCN dimer has been analyzed. Observed transition frequencies have been combined with previously recorded microwave data to obtain the following molecular parameters (in cm−1): ν2=3241.5696(8), α2=−0.000 110(1), B″=0.058 233 92(1), B′=0.058 344(1), D″J =0.7013(52)×10−7, DJ =0.6636(18)×10−7. The observed full widths at half-maximum intensity of the observed transitions are consistent with excited state lifetimes of 1.7(4)×10−9 s.