ATM-29

Einstein A lifetime

Spontaneous emission.

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AtomicEinstein A

Governing equation

\tau=1/A_{21}

where

A_{21}: A (1/s)
\tau: Lifetime (ns)

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-29 — Einstein A lifetime) is the form associated with Einstein A. Working symbols: $A_{21}$ $\rightarrow$ $\tau$ . Spontaneous emission.

Purpose

Purpose: compute

\tau

from

A_{21}

in Atomic physics via

\tau=1/A_{21}

Spontaneous emission. 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

A_{21} = 1.000e+8\,\mathrm{1/s}

, the governing relation

\tau=1/A_{21}

yields

\tau = 10.000\,\mathrm{ns}

. Spontaneous emission. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

A A_{21}100000000 1/s

Outputs

Lifetime \tau10.000 ns

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Narration of this film

Spontaneous emission.

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