The output of an FT-IR is an interferogram which is the sum of many cosine waves. Why is this so? Why does this pattern have a "center burst" followed by rapidly decreasing intensity? The cosine waves have audio frequencies. What is the connection between the moving mirror velocity and the frequency of these cosine waves? This data must be truncated. Give two reasons why the data must be truncated? If we use a boxcar function (rectangular pulse) to truncate the data the transform of the data produces spectral lines with feet. What do feet mean? Show that the transform of the product of a rectangular pulse and a cosine wave is the convolution of a sinc function and a frequency shifted delta function at the frequency of the cosine wave, that is, a sinc function at the frequency of the cosine wave. To get rid of the feet we use an apodization function such as a triangle function. Show that the transform of the product of a triangle function and a cosine wave is the convolution of a shifted delta function and a sinc squared function, that is, a sinc squared function at the frequency of the cosine wave.