coherent anti-Stokes Raman spectroscopy

Coherent anti-Stokes Raman spectroscopy (CARS) is a technique that uses two powerful laser beams to interact with a sample. When the frequency difference between these lasers matches a molecular vibration or rotation, it enhances wave mixing. This process generates signals at specific frequencies, with the anti-Stokes frequency being particularly useful because it's easily separated from the original beams and fluorescence.1

CARS is a more intense version of Raman spectroscopy, producing signals 10,000 to 100,000 times stronger. This allows for faster spectrum recording and better discrimination against background noise, making it suitable for analyzing molecules in flames or plasmas. The technique requires precise laser intensity stabilization but can analyze very small sample sizes.1