Linewidth Estimates

The linewidths helpers offer quick calculations for Doppler and collisional broadening effects. They return parameters that can be fed directly into the line-shape constructors.

API

SpectraUtils.sigma_doppler — Function

sigma_doppler(f0, T; m)

Return the Doppler Gaussian standard deviation for a transition at frequency f0 and temperature T (in kelvin). The molecular mass m is supplied as a keyword argument and should be expressed in kilograms.

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SpectraUtils.gamma_hard_sphere — Function

gamma_hard_sphere(p, T; μ, cs)

Compute the Lorentzian half-width at half-maximum (in cm⁻¹) under the hard-sphere collisional model. The calculation uses the pressure p (Pa), temperature T (K), reduced mass μ (kg), and average relative speed cs (m/s).

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Example

using SpectraUtils

σ = sigma_doppler(5.74e14, 300; m=28 * 1.66054e-27)
γ = gamma_hard_sphere(50, 300; μ=14 * 1.66054e-27, cs=450)
Voigt(σ, γ)

The formulas are intentionally lightweight and are best suited for quick estimates or as building blocks inside more sophisticated models.