ULTRA-SHORT MOLECULAR ROTATIONAL DIFFUSION TIMES MEASURED BY TIME INTEGRATED FLUORESCENCE

摘要

In this paper we present the first measurements of sub-nanosecond molecular rotational diffusion dynamics in fluorescent molecules. These measurements were obtained using a novel technique in which a liquid sample is excited with two femtosecond laser pulses with a controlled delay between them. The anisotropy generated by the first pulse modify the dipolar orientation of the pumped molecules, and consequently the fluorescence produced by the delayed pulse. The temporal analysis of this change allows the evaluation of the rotational time studying the total fluorescence produced as a function of the time delay.