A SURROGATE FOR DEBYE-WALLER FACTORS FROM TIME RESOLVED STOKES SHIFTS
Qin Zhong, Marcus T. Cicerone
Time-resolved Stokes shift (TRSS) data for rhodamine 6G in four glass-forming liquids are obtained with multi-channel TCSPC technique. Comparing the TRSS decays and time-of-flight neutron scattering in glycerol, we show that TRSS can be used to recover the short-time behavior of the intermediate scattering function, F(q,t) for wave vector q values near the peak in the static structure factor. We use the short time TRSS data from all four liquids to extract Debye-Waller factors, and apply these to a recently proposed relationship between α relaxation and <u2>. This provides an approach that is conceptually simple and also easy to implement to measure fast dynamics of glassy materials, which could be a key factor for protein preservation. After applying this measurement on sugar glasses used for protein preservation, based on the TRSS data, an idea to extract fast dynamics information of such material directly from temperature-dependent steady-state fluorescence spectra has been proposed and under examination.