Vibrational predissociation in D2HF

Calculations are presented of linewidths for the vibrational predissociation of D2HF induced by excitation of the HF stretching vibration in the weakly bound molecule. A potential energy surface based on ab initio computations with the correct leading multipole terms has been used. The vibrational predissociation linewidths are obtained from accurate close-coupling computations of scattering resonances for the D2+HF collision. The calculated linewidths are in excellent agreement with those obtained from infrared absorption experiments and confirm that the mechanism for vibrational predissociation is D2HF(v=1) →D2(v1=1) +HF(v2=0). It is found that the vibrational predissociation linewidths associated with the Σ vibration in para-D2HF are about five times narrower than those for the Π vibration. This implies that it should be possible to observe the D2HF (v=0, Π→v=1,Σ) transition in infrared spectroscopy measurements. The rotational distributions of the D2+HF products of the vibrational predissociation process are predicted and should be observable.