The infrared spectra of nitrous oxide–HF isomers

Two spectroscopically distinct isomers of a hydrogen bonded complex between nitrous oxide and hydrogen fluoride are observed by direct infrared laser absorption detection in a slit supersonic expansion. The linear isomer FH–NNO contains a relatively rigid hydrogen bond to the nitrogen end of NNO. The bent isomer NNO–HF has a stronger hydrogen bond to the oxygen end of NNO, but this bond is characterized by a softer bending potential and thus the complex exhibits evidence of large amplitude bending motion. Rapid vibrational predissociation, as determined from the homogeneous broadening of the rovibrational absorption structure, is evidenced in both isomers. The linear isomer exhibits predissociation lifetimes which show structure as a function of the upper J′ rotational level, including narrow resonances which suggest excitation of NNO fragment vibrational modes.