Surface melting on the (0001) face of hexagonal ice (I-h) was Studied by su
m-frequency vibrational spectroscopy in the OH stretch frequency range. The
degree of orientational order of the dangling OH bonds at the surface was
measured as a function of temperature. Disordering sets in around 200 K and
increases dramatically with temperature. The results show that the disorde
red (quasiliquid) layer on ice is structurally different from normal liquid
water.