Two-photon photochromism

{
  "id": "MLC-T-CHM-012382",
  "term": "Two-photon photochromism",
  "field": "Chemistry",
  "definition": "A photochromic process initiated by the simultaneous absorption of two photons, leading to a reversible change in a molecule's absorption spectrum. This allows for three-dimensional optical data storage and imaging with enhanced spatial resolution due to the non-linear nature of the excitation. The absorption of two photons typically occurs at wavelengths where single-photon absorption is negligible.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "two-photon process"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 436 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/two-photon-photochromism/"
}