C_24Cs samples containing oriented N_2 molecules

摘要

The adsorption of N_2 molecules inside C_24Cs has been studied in detail as a function of temperature and pressure using n-diffraction and nuclear resonance photon scattering (NRPS). Large differences were observed between samples derived from highly oriented pyrolytic graphite and those prepared from graphite powder. The tilt angle of the N_2 molecular axis was determined by using NRPS and found to lay nearly parallel to the graphite planes. The amount of adsorbed N_2 increased with decreasing temperatures, reaching saturation composition C_24Cs(N_2)_1.5 at approximately 100 K with an initial N_2 pressure of 2 bar. At higher pressure, 9 bar, two new phases were formedt a second stage C_32Cs(N_2)_2.1 and a first stage C_16Cs(N_2)_1.8 at T < 170 K and are discussed in detail.