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Photothermal Calculator

Given a metallic nanoparticle, a host medium, and a focused CW laser, compute the power budget (absorption vs scattering) and the steady-state temperature rise at the particle surface. Physics: exact Mie theory.

Parameters

Model. I = 2P/(πw0²) (Gaussian peak). Pabs = σabs·I. ΔT = Pabs/(4πκR) at the surface; T(r) − T∞ = Pabs/(4πκr) for r ≥ R. σabs from exact Mie theory.

Cross-sections vs wavelength
σabs σsca laser λ
Apparent color
scattered
transmitted
σabs
— nm²
σsca
— nm²
σext
— nm²
Albedo
—
Power at particle —
absorbed —
scattered —
T(r) − T∞ vs. r / R  ·  dots mark 1/e (r = e·R) and 1/e² (r = e²·R)

Radial Temperature Profile

— K at the particle surface

Steady-state point-source approximation outside the particle: ΔT(r) = ΔT(R)·R/r for r ≥ R.

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References & data sources

  • G. Baffou & R. Quidant, Thermo-plasmonics: using metallic nanostructures as nano-sources of heat, Laser & Photonics Reviews 7, 171 (2013). Foundational review on photothermal generation with metallic nanoparticles.
  • C. F. Bohren & D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, 1983). Mie theory.
  • Optical constants: refractiveindex.info — Au/Ag: Johnson & Christy (1972); Al: Rakić (1995); Si: Aspnes & Studna (1983).