The chromium film does not seem to exhibit any noticeable shift as in the previous graphs. There is however an indication that with decreased wavelength the increase in intensity is delayed slightly after the plasmon angle. There are a couple issues that need to be addressed at this point. These issues are absorption of light into the material medium through which the light travels and reflection of the light at the air-glass interface. As a result, the graphs that are given above could be deformed representations of the true surface plasmon phenomenon.
Light is absorbed when it travels through a transmitting medium.
The Fresnel Relation for the reflection coefficient obtained earlier was used to calculate whether there was a significant change for the light reflected from the glass-air interface. The reflection coefficient was approximately 20 percent throughout the angles rotated through for the incident beam and approximately 19 percent throughout for the reflected beam. With such little variation the reflection coefficient was also treated as a negligible factor. Because of the consistency of absorption and reflection, the plasmon angle, as found from the intensity curves above are unchanged by these complications. Because these graphs are reliable for the plasmon angle it is apparent that there is an increase in the plasmon angle with an increase in the wavelength of light used with the notable exception of the chromium film.