Biphotonic excitation

{
  "id": "MLC-T-CHM-001339",
  "term": "Biphotonic excitation",
  "field": "Chemistry",
  "definition": "A single coherent event in which a molecule absorbs two photons at once, whether of equal or different wavelength, so that the excitation energy equals the sum of the two photon energies. It is also called two-photon excitation and requires high photon flux, as supplied by pulsed lasers. Absorption of a second photon by an already excited state is a stepwise process instead.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "absorption",
    "photon",
    "two-photon excitation",
    "wavelength"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 308 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/biphotonic-excitation/"
}