A potassium lamp shows a doublet at and in air

PHYSICS · Multi-part · Fermi University Physics · Atomic, Molecular & Optical Physics · One-electron atoms and the origins of atomic structure · Many-electron atoms and the periodic table

Reading the Spectrum, Ch Lines, series and the term diagram: what a spectrometer measures

Problem

A potassium lamp shows a doublet at

766.490\,\mathrm{nm}

and

769.896\,\mathrm{nm}

in air. Use the vacuum correction

\lambda_{\rm vac} = 1.000274\,\lambda_{\rm air}

. ((a)) Find both vacuum wavenumbers, in

\mathrm{cm^{-1}}

. ((b)) Find the wavenumber splitting between the two lines. ((c)) Recompute the splitting by inverting the two air wavelengths directly, skipping the vacuum correction, and comment on how this compares with the splitting found in part (b) and with the shift in each individual line.

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