Analysis of particle motions by fluorescence correlation spectroscopy with traveling interference fringe excitation in biological membranes

A new improved method of fluorescence correlation spectroscopy, fluorescence correlation spectroscopy with traveling interference fringe excitation, for determining motional states of particles is described. In this method, the modulated fluorescence signal from particles excited by an interference fringe moving at constant velocity is detected. The autocorrelation function of the fluorescence intensity consists of terms which are characterized by the size of the excitation region and the spacing of the fringe. A lock-in detection method is adopted for extracting cosine and sine Fourier coefficients at the frequency of the traveling fringe (Fcos(t), Fsin(t)). Autocorrelation functions of Fcos(t) and Fsin(t) were found to express the motion of the fluorescent particles. The potential of this method for analyzing of the motional modes of particles in biological membranes is discussed.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.