Thermal diffusion depth

{
  "id": "MLC-T-CHM-011938",
  "term": "Thermal diffusion depth",
  "field": "Chemistry",
  "definition": "The characteristic distance into a sample that a thermal wave penetrates during a periodic heating experiment, such as in photothermal spectroscopy. This depth is determined by the thermal diffusivity of the material and the modulation frequency of the heating source, which is often a laser. The thermal diffusion depth is inversely proportional to the square root of the modulation frequency, meaning slower heating cycles probe deeper into the material.",
  "synonyms": [
    "thermal wave decay length"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "electromagnetic radiation",
    "thermal diffusivity"
  ],
  "references": [
    "PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 766 (https://doi.org/10.1515/pac-2019-0203)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/thermal-diffusion-depth/"
}