Dynamics of ice surfaces
Dr. E. Backus
Although ice is abundant on earth and in the atmosphere, its surface structure is poorly understood. The surface is important as many reactions are taking place on it. In this project, which is a collaboration with the group of M.J. Shultz from Tufts University and the group of H.J. Bakker from FOM Institute AMOLF, we study the structure and dynamics of the outermost molecular layer of an ice crystal in order to understand the structure and reactivity better. For example we can get information about the reorientation time of the water molecules, and how this depends on temperature.
We will study the surface dynamics by applying time-resolved sum-frequency generation spectroscopy. In this technique we label a particular vibration by an infrared pump pulse. At a certain time afterwards we probe the vibrations at the surface by exciting with a weak infrared beam and this excitation is subsequently upconverted with a visible beam. The sum-frequency emission gives us then the infrared spectrum. Changing the time between the pump and the probe pulses will give dynamical information.
Cho-Shuen Hsieh, R. Kramer Campen, Ana Celia Vila Verde, Peter Bolhuis, Han-Kwang Nienhuys, and Mischa Bonn, Phys. Rev. Lett. 107 (2011) 116102
Irene Li Barnett, Henning Groenzin, and Mary Jane Shultz, J. Phys. Chem A, 115 (2011) 6039
Henning Groenzin, Irene Li, and Mary Jane Shultz, J. Chem. Phys. 128 (2008) 214510