Measuring Molecular Order and Orientation Using Coherent Anti-Stokes Raman Scattering Microscopy

: Coherent anti-Stokes Raman scattering microscopy develops rapidly into a powerful technique to image both the chemical composition and physical state in complex samples from biophysics, biology, and the material sciences. This nonlinear vibrational technique increases the signal relative to spontaneous Raman scattering and does not require labeling of the specimen. A theoretical description of the technique is provided and the two major modes of operation: picosecond- and multiplex coherent anti-Stokes Raman scattering are discussed. The potential of the technique is demonstrated with examples of direct measurement of acyl chain order and orientation in lipid monolayers, bilayers, and lipid vesicles.