Site and orientation resolved SFG H–O vibration frequency. Undercoordination resolves the frequencies of the OB1:H–OB2 and the OB1 – H:OB2 bonds (inset) between outermost two sublayers of the ice Ih(0001) skin.[35] Insets illustrate segmental bond lengths, orientations, and frequencies of the H–O stretching vibrations. The positive peak (< 3270 cm−1) corresponds to the H–OB2 vibration (shaded in green) and the valley (> 3270 cm−1) to the OB1-H (shaded in blue). The less coordinated OB1-H is shorter and stiffer and its H:OB2 is longer and softer than the OB1:H–OB2. |
