Quantum counter

{
  "id": "MLC-T-CHM-009761",
  "term": "Quantum counter",
  "field": "Chemistry",
  "definition": "A medium, usually a concentrated dye solution, whose emission quantum yield stays the same at every excitation wavelength over a stated range, so its emitted intensity is proportional to the number of photons it absorbs. Placed in the excitation beam of a spectrofluorometer, it acts as a detector of relative photon flux and corrects excitation spectra for lamp and monochromator variation. Concentrated rhodamine B is the widely used example; it measures photon flux and does not give the quantum yield of any sample.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "excitation energy",
    "photon flux",
    "quantum yield"
  ],
  "references": [
    "Orange Book, 2nd ed., p. 193 (https://media.iupac.org/publications/analytical_compendium/)",
    "PAC, 1984, 56, 231. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI: molecular luminescence spectroscopy' on page 238 (https://doi.org/10.1351/pac198456020231)",
    "PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2267 (https://doi.org/10.1351/pac199668122223)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/quantum-counter/"
}