Image
Infrared absorption spectra for the
OCSparahydrogen complex in
helium-4 droplets at 0.38 K (top)
and in helium-3/helium-4 droplets
at 0.15 K (bottom). Both spectra
show contributions from droplets with
14, 15 and 16 parahydrogen molecules.
Note that the sharp spectral peaks
seen at 0.38 K are absent at
0.15 K. This is evidence for
superfluidity.