THE INFRARED ABSORPTION SPECTRUM OF THE AMMONIUM ION IN LATTICES OF THE NaCl TYPE

摘要

In the past ten years considerable progress has been' made in the study of the crystal structure of hydrogen containing compounds. This has been mainly the result of effective use of new theor?etical methods in infrared and Raman spectroscopy, as well as of the availability of new tools in crystal structure analysis, such as neutron diffraction and nuclear magnetic resonance. The ammonium halides have been studied frequently. The reasons for the interest in these compounds is explained in chapter I. A summary is given of, some data on the transitions between the four phases in which ammonium chloride, bromide and iodide occur. The present understanding of the nature of the structural changes which accompany the phase transitions is discussed.