CHEM 2323 Study Guide - Midterm Guide: Wavenumber, Specific Strength, Spectroscopy
Document Summary
Chapter 12: infrared spectroscopy (ir) and mass spectrometry (ms) Infrared spectroscopy is a type of imaging technique that uses infrared light that causes the bonds of a molecule to vibrate , or stretch. The energy that is absorbed to stretch the bonds of a molecule is measured through a spectrum, which can be used to analyze properties of the molecule of interest. An infrared spectrum is the actual graph that shows the energy absorbed by the molecule in relation to the wavelength of light used. Below is an example of what an ir spectrum looks like. Usually, you will see the ir spectrum graph the transmittance (absorbance) versus the wavenumber (inverse of wavelength, in units of cm-1). Notice the region between 400 cm-1 and 1400 cm-1. This region is called the fingerprint region, because the bands (the peaks representing the different stretches of the molecule), is unique to each different molecule.
