Sum-frequency spectroscopy

{
  "id": "MLC-T-CHM-011580",
  "term": "Sum-frequency spectroscopy",
  "field": "Chemistry",
  "definition": "A nonlinear optical spectroscopic method that involves the interaction of two incident laser beams with different frequencies at an interface to produce a signal at their sum frequency. This technique is intrinsically surface-specific because the sum-frequency generation process is forbidden in centrosymmetric bulk media. It is used to probe molecular vibrations and orientation at surfaces and interfaces.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "infrared radiation",
    "pulsed laser"
  ],
  "references": [
    "PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 765 (https://doi.org/10.1515/pac-2019-0203)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/sum-frequency-spectroscopy/"
}