The measurement of the optical constants (n, k) of pure chromium, aluminum, and chromium/aluminum double layer films with different thickness combinations using the surface plasma excitation is studied in this thesis. The Kretschmann ATR (attenuated total reflection) technique is employed to excite the surface plasma waves at a metal-air interface in the experiment. The simplex method was used for data fitting to determine the optical constants and the thickness of the films from the measurements.
The reflectivity of a pure aluminum film will drop to the minimum value at resonance. Its surface plasma angle is around 43 degrees which is very close to the theoretical predictions. The reflectivity of pure chromium and all bilayer films can not drop to a minimum value.
In the graph of (n, k) versus the thickness of thin films, the values of n revealed almost a linearly increasing tendency as aluminum is decreased and chromium is increased while maintaining a total thickness of around 200A.
The k data curve is observed to drop sharply for two double-layer samples. One sample is 3OA of chromium and 170A of aluminum. The other sample is 50A of chromium and l50A of aluminum. This trend in the k data is interesting since it is not monotonic.
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