(9) Internal Revenue Code means the Internal Revenue Code of 1986 in effect for the federal tax year beginning on January 1, 2007, not including any changes made by federal law after that date, and any regulations adopted under that code applicable to that period.
Absorbance is the negative logarithm of the percent transmittance divided by 100. A spectrophotometer can be set to measure either the percent transmittance or the absorbance of a solution. In lab, you will be using a spectrophotometer called the Spectronic 20 or Spec 20 to measure absorbance.
The goal of any absorption spectroscopy (FTIR, ultraviolet-visible (UV-Vis) spectroscopy, etc.) is to measure how well a sample absorbs light at each wavelength.TIR is a method of measuring an infrared absorption spectrum. For a discussion of why people measure infrared absorption spectra, i.e. why and how substances absorb infrared light, see the article: Infrared spectroscopy.