thermal diffusion depth

symbols: L, μs, units: m, μm
synonym: thermal wave decay length
https://doi.org/10.1351/goldbook.08696
In photoacoustic spectroscopy, L=(D/πf), where D is thermal diffusivity and f is modulation frequency of the electromagnetic radiation.
Notes:
  1. SI unit: m. Common unit: μm.
  2. 63 % of the PAS signal originates within the thermal diffusion depth.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 766 [Terms] [Paper]
Citation: 'thermal diffusion depth' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08696 RIS BibTex EndNote
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