Photon fluence

{
  "id": "MLC-T-CHM-008899",
  "term": "Photon fluence",
  "field": "Chemistry",
  "definition": "The count of photons that pass into a tiny spherical probe, whatever direction they come from, divided by the probe's cross-sectional area, giving a count per unit area, in SI units photons per square metre. Using a sphere means that every direction of arrival counts equally, so the quantity describes the total photon exposure at a point in space. It is the photon-number counterpart of the energy fluence, which is measured in joules per square metre.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "Avogadro constant",
    "irradiation",
    "photon fluence rate"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 395 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/photon-fluence/"
}