Measurement of a Preresonant Hyper-Raman Hyperpolarizability

Four wave mixing (FWM) spectroscopy is used to measure a preresonant hyper-Raman hyperpolarizability. The four wave mixing process known as hyper-difference frequency generation (HDFG), which depends upon the hyper-Raman hyperpolarizability, can be measured simultaneously with other well-studied four-wave mixing processes, which serve as an internal standard. We use coherent anti-Stokes Raman (CARS) response from deuterobenzene to quantify the acetonitrile ν(CN) hyper-Raman hyperpolarizability. This internal standard method is applicable to any infrared active vibration and greatly diminishes the barriers to quantification of hyper-Raman hyperpolarizabilities.