Raman correlation spectroscopy: A method for studying chemical composition and dynamics of disperse systems

Raman correlation spectroscopy—intensity fluctuation spectroscopy of Raman-scattered light from a small sample volume—has been demonstrated. A modified confocal Raman microscope is used to observe number fluctuations of colloidal particles caused by Brownian motion. Correlation analysis of the fluctuations yields mobility and number density of the particles. In mixed systems, particles are differentiated according to their chemistry by selecting characteristic Raman bands for detection. Cross correlation of the signals from different Raman bands has been demonstrated. This method extends the domain of optical fluctuation spectroscopies to Raman scattered light, combining the chemical identification obtained by Raman scattering with the structural and dynamical information obtained by correlation spectroscopy.