in an argon glovebox and a portion of the sample placed in a quartz cell of known volume fitted with a thermocouple that is in direct contact with the sample the sample was activated at 523 k under vacuum 1 u00d7 10 u2212 4 torr for one hour and allowed to cool to room temperature at room temperature high purity 99 999 hydrogen was expanded from a known volume into the evacuated sample cell to give an initial hydrogen pressure of ca 10 psia the sample was heated to ca 750 k to promote the hydriding of the sample as detected by a decrease in hydrogen pressure after the system had reached an equilibrium pressure the cell was cooled to 87 k under the hydrogen atmosphere while holding the sample at 87 k the hydrogen was evacuated from the cell total evacuation time of 15 minutes a temperature programmed desorption tpd experiment was then conducted using the following procedure the sample was warmed at a constant rate from 87 k to ca 825 k during this heating the sample cell was held under a dynamic vacuum from a turbo molecular pump simultaneously pressure changes in the cell were recorded using a sensitive pressure transducer and a gas phase hydrogen ion count was recorded using a mass spectrometer also used to assay for evolution of gases other than hydrogen the results of the tpd experiment fig1 show the presence of hydrogen desorption in.