Transmission Infrared Spectroscopy of Ammonia Borane

Transmission infrared spectroscopy can potentially offer unique advantages in studying the mechanisms of hydrogen loss from complex hydrides that are being considered for use as hydrogen storage materials. An apparatus that permits infrared spectra to be obtained over a temperature range of 85 to 1200 K and under either an ambient pressure of selected gases or under vacuum has been designed and its performance characterized. While the method is capable of producing high quality spectra at room temperature and below, several difficulties arise as the sample temperature is increased to the point where hydrogen loss occurs. These challenges include reaction with the host matrix, reaction with residual water or oxygen in the system, and loss of transparency of the sample. The performance of the method is illustrated with spectra obtained for ammonia borane, NH 3 BH 3 .