Energy States in Solids With Particular Reference to NdCl36H2O

The absorption spectra of NdCl36H2O has been photographed at 78°K, 169°K and 200°K. Two low lying excited states were found, located at 62 and 250 cm—1 above the basic state. These three levels presumably arise from a splitting of the basic state of Nd+++(4J9/2) in a predominantly cubic field. The over-all splitting is slightly smaller than that which was found for the sulphate, and the relative splitting is slightly different. The differences reflect the change in crystal field which is brought about by the break in the homologous series of the hydrated chlorides of the rare earths between Nd and Pr.