The main focus of my research is to study biological processes by monitoring the spatial distribution and chemical transformation of multiple molecular components in a cell or biologically relevant systems. To achieve this goal, we need a non-invasive, label-free chemically selective microscopic method. Coherent anti-Stokes Raman scattering (CARS) is emerging as a powerful microscopy contrast mechanism in this regard because it achieves equivalent vibrational information to spontaneous Raman scattering, but produces much stronger signal levels. We are developing new multiplex CARS techniques, which can measure the vibrational spectrum over the entire fingerprint region with great sensitivity. The identity, distribution and chemical changes of multiple molecular species can be studied to understand the molecular level dynamics during important cellular processes.

In the vicinity of metal nanoparticles, the CARS signal can be enhanced significantly further. By controlling the structure of the nanoparticles to optimize the surface enhancement of the CARS signal, we will try to achieve the signal sensitivity necessary to monitor a single molecule’s vibrational spectrum. Eventually, the evolution of the vibrational spectrum of a single protein molecule during enzymatic functioning will reveal valuable information about the functioning mechanisms.