Spectre vibrationnel des tricyclophosphates KMIIP3O9 de structure benitoite

The Raman and i.r. spectra of tricyclophosphates KMIIP3O9 (MII = Mg, Ca, Co, Mn, Zn, Cd) with the benitoite structure are discussed on the basis of a factor group analysis, and by comparison with the spectrum of the structurally related LaP3O9. 3 H2O. Most of the stretching frequencies have been observed and assigned, whereas the assignment of the bending modes remains more or less hypothetical. Low-frequency i.r. bands have been assigned to translations of either K or MII cations on the basis of mass effects. The influence of the ring chain polymorphism is briefly discussed. © 1987

t-Curves for n-Hexane

The adsorption and desorption isotherms of n-hexane on powdered alumina and silica have been studied at 25°C over a wide range of relative pressures. Two t-curves for pore structure analysis are proposed, one for alumina (C = 12) and the second for silica (3 ≤ C ≤ 9). The statistical thickness t of the adsorbed n-hexane layer has been drawn as a function of the relative pressure assuming a maximal thickness of 0.55 nm and a mean thickness of 0.42 nm for the monolayer. The results are discussed in relation to previous published data