Chapter 12 ?2010, Prentice Hall Organic Chemistry, 7th Edition L. G. Wade, Jr. Infrared Spectroscopy and Mass Spectrometry Chapter 12 * Introduction Spectroscopy is a technique used to determine the structure of a compound. Most techniques are nondestructive (it destroys little or no sample). Absorption spectroscopy measures the amount of light absorbed by the sample as a function of wavelength. Chapter 12 Chapter 12 * Types of Spectroscopy Infrared (IR) spectroscopy measures the bond vibration frequencies in a molecule and is used to determine the functional group. Mass spectrometry (MS) fragments the molecule and measures their mass. MS can give the molecular weight of the compound and functional groups.