Rotational and vibrational dynamics of H2O and HDO in helium nanodroplets

Imidazole Trimer-Water Complexes in Superfluid Helium Nanodroplets: Water Stretching Modes

“…The spectra (a), (b), and (c) were recorded at the pick-up IM oven temperatures of 39, 48, and 61 o C, respectively. The bands near 3730 cm −1 are due to water monomer and high order water clusters, 18,19 since those were obtained when the IM oven was absent and only the water source was open. No vibrational bands were observed in this spectral region when the water line was closed and only the IM oven was on.…”

“…Therefore, the vibrational bands except for the bands marked with "w" must then be attributed to the clusters of IM and their clusters with H 2 O. Indeed, the bands labeled as "w" and "w 2 " are due to the P(1) line of a single water molecule 18,19 and the OH stretching bands of H 2 O donor molecules in the water dimer, [18][19][20] respectively. The band marked with "^" is due to water-nitrogen complexes from air-leak experiments.…”

High resolution IR spectroscopy of HDO and HDO(N2)n in helium nanodroplets

“…The lifetime of the O-D stretch compares well with that of the O-H stretch of HOD, 16 indicating a possible quenching of the Fermi resonance by the superfluid He matrix. Based on the pressure dependency of the line intensity, we assigned the line at 2732.4 cm −1 to a water-nitrogen dimer and the 2730.6 cm −1 signal to the water-͑N 2 ͒ 2 trimer.…”

“…2͒ could be fitted well by a Lorentzian line shape with full width at half maximum ͑FWHM͒ of 0.060͑4͒ cm −1 , which corresponds to a lifetime of 87.9͑6͒ ps. 16 The field-induced transition showed a lineshape with a tail to the blue, indicating an inhomogeneous broadening mechanism. Inhomogeneous broadening may occur due to the fact that the molecules are embedded in helium droplets of different sizes.…”

“…Lindsay et al 16 concluded that the lifetime is predominantly limited by rotational relaxation since no vibration is in close proximity. In both cases, similar linewidths and hence lifetimes are observed ͓87.9͑6͒ ps versus 97.3 ps ͑Ref.…”