ADSORPTION AND COADSORPTION OF MOLECULAR-HYDROGEN ISOTOPES IN ZEOLITES - II - INFRARED ANALYSES OF H-2, HD, AND D-2 IN NAA

The infrared analysis of the induced bands of molecular hydrogen isoto pes, adsorbed in NaA zeolite, shows several features; (i) when the amo unt of adsorbed molecules increases, the bands become complex, showing ,three components, which can be related to different energetic situati on of the molecules in the cavity; (ii) the band frequency is lower th an the gas frequency; for each species the shifts are proportional to the inverse square root of the mass (same interaction with the crystal ); (iii) the absolute intensity increases when the temperature decreas es, this is due to the fact that the molecule remains longer in the vi cinity of the adsorption site where the electric held is the highest. Its amplitude is deduced from the absolute intensities measured at the lowest temperature (similar to 10(10) V/m, in agreement with other re sults). (C) 1998 American Institute of Physics. [S0021-9606(98)70236-3 ].