Fundamental absorption

{
  "id": "MLC-T-CHM-004720",
  "term": "Fundamental absorption",
  "field": "Chemistry",
  "definition": "Absorption of light in a semiconductor or insulator that lifts electrons straight across the band gap, out of the filled valence band and into the empty conduction band. It is the band-to-band transition of lowest energy, so it sets in at the absorption edge, where the photon energy reaches the band gap energy. Silicon, with a gap near 1.1 eV, absorbs at wavelengths shorter than about 1100 nm.",
  "synonyms": [
    "intrinsic absorption"
  ],
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "extrinsic absorption"
  ],
  "references": [
    "PAC, 2011, 83, 931. 'Glossary of terms used in photocatalysis and radiation catalysis (IUPAC Recommendations 2011)' on page 954 (https://doi.org/10.1351/PAC-REC-09-09-36)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/fundamental-absorption/"
}