Professor Ashis Mukhopadhyay
Soft materials such as polymers, colloids, membranes, liquid crystals comprise almost all materials of our everyday life, including life itself. They are neither simple liquids, nor crystalline solids and many of the fascinating and useful properties of these materials result from thermal fluctuations in the local nanoenvironment. Research on these materials have become in recent years an exciting example of an emerging, interdisciplinary field of science drawing upon physicists, chemists, biologists, chemical engineers and materials scientists. The goal of our laboratory is to conduct fundamental research in the field of soft materials by developing spectroscopy techniques, which can offer structural and dynamical information with unprecedented spatial and temporal resolution, down to the atomic and molecular scale. The laboratory uses two main experimental approaches: (i) Infrared spectroscopic ellipsometry, which can describe the identity, composition, molecular interaction and orientation of the various parts of the molecules, as well as the thickness of the adsorbed film in the same measurement of the same sampling area. (ii) Fluorescence correlation spectroscopy using which the rate of dynamic processes such as diffusion, aggregation and chemical reactions can be inferred from the fluorescence-intensity autocorrelation function. The single-molecule sensitivity of this technique allows complementing, ensemble-averaged rate measurements of traditional methods of physical analysis with the distribution around the average. This is important to understand the issue of heterogeneities in soft matter systems. We are interested in a broad agenda of research problems including (i) micro- and nanofluidics with complex fluids (ii) single-molecule diffusion in confined fluids (iii) interfacial behavior of fluids at soft surfaces and (iv) direct visualization of molecules during spreading.