An electron energy-loss spectrum recorded from a thin metal film in a transmission…

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

Solid State Physics, Ch Collective and coupled excitations: plasmons, polaritons and polarons

Problem

An electron energy-loss spectrum recorded from a thin metal film in a transmission electron microscope shows:

1000

counts in the zero-loss (elastic) peak,

350

counts in a peak at an energy loss of

12.0\,\mathrm{eV}

, and

60

counts in a peak at an energy loss of

24.0\,\mathrm{eV}

, with no other features below

50\,\mathrm{eV}

. Separately, the inelastic mean free path for plasmon scattering at the electron energy used is measured as

\lambda=105\,\mathrm{nm}

. ((a)) Identify the plasmon energy of this metal and explain what the

24.0\,\mathrm{eV}

peak is. ((b)) Multiple-loss intensities follow a Poisson distribution in specimen thickness

t

, with mean number of losses

\mu=t/\lambda

and

I_n/I_0=\mu^n/n!

. Use the single-loss peak to estimate the specimen thickness, and check the result against the double-loss peak.

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