ATM-33

Doppler width

Thermal broadening.

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AtomicDoppler

Governing equation

\Delta\nu/\nu=\sqrt{2kT\ln2/mc^2}

where

T: T (K)
m: Mass (u)
\Delta\nu/\nu: Fraction (—)

Lecture brief

Historical brief

Balmer, Rydberg, Bohr (1913), fine structure, Zeeman and Stern–Gerlach built the spectrum of one atom. The lab computes levels, selection and magnetic splitting. This sheet (ATM-33 — Doppler width) is the form associated with Doppler. Working symbols: $T$ , $m$ $\rightarrow$ $\Delta\nu/\nu$ . Thermal broadening.

Purpose

Purpose: compute

\Delta\nu/\nu

from

T

m

in Atomic physics via

\Delta\nu/\nu=\sqrt{2kT\ln2/mc^2}

Thermal broadening. Use it when a real atomic physics question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

T = 5000.000\,\mathrm{K}

m = 1.000\,\mathrm{u}

, the governing relation

\Delta\nu/\nu=\sqrt{2kT\ln2/mc^2}

yields

\Delta\nu/\nu = 2.532e-5\,\mathrm{—}

. Thermal broadening. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

T T5000 KMass m1 u

Outputs

Fraction \Delta\nu/\nu0.00002532 —

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Narration of this film

Thermal broadening.

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