We measured spectra at 8 K before heating and after heating at 15, 20, and 25 K. The numbers of 1-6 indicate the sizes of deuterated water clusters while the vertical bars show the scales of absorbance. The wavenumber of the horizontal axis is proportional to the frequency of light, i.e. 33 cm^-1 ≈ 1 THz. The increase in absorbance means that the amount of the corresponding cluster got larger.