The left hump is the P branch and the right hump is the R branch. Again, we see the P branch on the left and the R branch on the right. Notice that in both bands, the P branch has a higher intensity than the R branch. This results from a quantum mechanical effect whereby the wave functions overlap in such a way to make P branch transitions more probable than R branch transitions. The horizontal scale is the micrometer reading on the Littrow grating.
Energy increases to the left.
Introduction Molecular Structure and Vibration Molecular Spectra Apparatus Return to Jim's homepage or Derek's homepage or Davidson Physics .