Two-photon excitation

{
  "id": "MLC-T-CHM-012381",
  "term": "Two-photon excitation",
  "field": "Chemistry",
  "definition": "The simultaneous absorption of two photons by a molecule to reach an excited electronic state. This process requires a high photon flux, typically achieved with pulsed lasers, and the sum of the energies of the two photons must match the energy difference between the ground state and the excited state. The probability of two-photon absorption is proportional to the square of the incident light intensity.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "biphotonic excitation",
    "excitation energy",
    "two-photon process"
  ],
  "references": [
    "PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2282 (https://doi.org/10.1351/pac199668122223)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/two-photon-excitation/"
}