Potassium sulphate crystals containing chromate ions show two broad bands in the region 2300-2650 Å and 3300-3750 Å. These bands contain a fine structure of alternately weak and strong lines. The set of strong lines is due to transitions from the ground state to vibrational levels of the excited state. The set of weaker lines is due to transitions from one of the vibration frequencies of the ground electronic state to vibration frequencies of the upper electronic state. © 1971.