Measurement of the temperature and pressure dependent tracer diffusion in a supercooled liquid studies by means of fluorescence correlation spectroscopy

We report on the possibility to perform temperature and pressure dependent FCS (and confocal microscopy) studies by using long working distance (LD)objectives without immersion liquid. The feasibility of using LD objectives for FCS experiment was critically tested [1]. Temperature and pressure dependent FCS studies which allow to measure the T,P-dependence of the self- (tracer-) diffusion coefficient and the reaction rate are important for several reasons: In complex and crowded systems the coupling of the diffusion coefficient to the viscosity, i.e. the Stokes-Einstein-Debye (SED) relation can be tested. In living cells and in vitro the effect of temperature and pressure on the rate of biochemical reactions can be studied. We have performed measurements of the self-diffusion coefficient as a function of T,P on a mixture of simple glass-forming liquid BMPC-OTP[2]