molecular cage.*

Fullerene molecules encapsulating one H₂O molecule have been synthesized using "molecular surgery" [1, 2]. Here we present the low-temperature far- and mid-infrared spectroscopy results of H₂O@C₆₀ and C₆₀ solid mixture studies. Para- and ortho-water lines were identified in the rotational and rovibrational spectra of H₂O@C₆₀. The vibrational frequencies of confined H₂O are red-shifted and the dipole moment is reduced with respect to the gas phase. The center-of-mass quantized translational mode of H₂O was observed at about 100 cm^-1. The splitting of spectral lines is explained by a model taking into account electrostatic fields present in solid C₆₀ [3].

1. K. Kurotobi and Y. Murata, Science 333, 613 (2011).
2. A. Krachmalnicoff, R. Bounds, S. Mamone, S. Alom, M. Concistr_e, B. Meier, et al., Nat. Chem. 8, 953 (2016).
3. A. Shugai, U. Nagel, Y. Murata, Jongjun Li, S. Mamone, A. Krachmalnicoff, S. Alom, R. J. Whitby, M. H. Levitt, and T. Rõõm, Infrared spectroscopy of endohedral H₂O in C₆₀, (unpublished)