This spectroscopic method relies on photons' frequencies being changed upon collision with matter; that shift corresponds to a change in a molecule's rotational or vibrational energy level.
For the chemical analysis of objects and powders under obscuring substances, the spatiallyÂ­offset form of this method is used. In another variant of this method, incident laser frequency is tuned to be close in energy to an electronic transition, allowing the study of compounds at low concentrations; that is the resonant form of this technique. Normal modes in centrosymmetric molecules cannot be active in both this technique and absorption spectroscopy. In this method, we look for modes that transform with the same symmetry as (*) quadratic forms, and are thus accompanied by a change in polarizability. This spectroscopic method relies on photons' frequencies being changed upon collision with matter; that shift corresponds to a change in a molecule's rotational or vibrational energy level. For 10 points, name this form of spectroscopy where we probe molecules by looking for Stokes and antiÂ­Stokes shifts, named for an Indian scientist.
For the chemical analysis of objects and powders under obscuring substances, the spatiallyÂ­offset form of this method is used.
Raman spectroscopy