Infrared spectra of N2O-(ortho-D2)N and N2O-(HD)N clusters trapped in bulk solid parahydrogen

High-resolution infrared spectra of the clusters N2O-(ortho-D-2)(N) and N2O-(HD)(N), N=1-4, isolated in bulk solid parahydrogen at liquid helium temperatures are studied in the 2225 cm(-1) region of the nu(3) antisymmetric stretch of N2O. The clusters form during vapor deposition of separate gas streams of a precooled hydrogen mixture (ortho-D-2/para-H-2 or HD/para-H-2) and N2O onto a BaF2 optical substrate held at similar to 2.5 K in a sample-in-vacuum liquid helium cryostat. The cluster spectra reveal the N2O nu(3) vibrational frequency shifts to higher energy as a function of N, and the shifts are larger for ortho-D-2 compared to HD. These vibrational shifts result from the reduced translational zero-point energy for N2O solvated by the heavier hydrogen isotopomers. These spectra allow the N=0 peak at 2221.634 cm(-1), corresponding to the nu(3) vibrational frequency of N2O isolated in pure solid parahydrogen, to be assigned. The intensity of the N=0 absorption feature displays a strong temperature dependence, suggesting that significant structural changes occur in the parahydrogen solvation environment of N2O in the 1.8-4.9 K temperature range studied. (C) 2007 American Institute of Physics.