A Raman spectrum of cadmium telluride

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Lattice dynamics and thermal properties of solids · Lattice dynamics and thermal properties of solids

Solid State Physics, Ch Phonons: quantisation, occupation and inelastic scattering

Problem

A Raman spectrum of cadmium telluride, excited at

632.8\,\mathrm{nm}

(

\hbar\omega_L=1.9593\,\mathrm{eV}

), shows its longitudinal optical phonon at

\hbar\Omega=21.0\,\mathrm{meV}

(

169\,\mathrm{cm^{-1}}

). A spectrometer that detects power records a Stokes to anti-Stokes intensity ratio of

4.80

. ((a)) Divide the optical factor

[(\omega_L-\Omega)/(\omega_L+\Omega)]^4

out of the measured ratio and calculate the sample temperature. ((b)) Calculate the temperature that would be inferred by reading

4.80

as the bare occupation ratio, and say how far it is in error.

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