Kinetic studies of the intercalation of 2H-NbSe2 with hydrazine by transmittance measurements

Abstract

Abstract Kinetic transmittance measurements at a fixed wavelength of 1600 nm have been made during the intercalation of thin single crystals of 2H-NbSe2 with gaseous hydrazine. Measurements have been made as a function of pressure at room temperature. The results indicate that adsorption of the adduct on the exposed crystalline surface is the first step of the reaction. A delay time measured before the changes in transmittance occur has been associated with the weakening of the van der Waals forces that hold together the planar macromolecules in the crystal. Subsequent changes in transmittance are explained by the insertion of adduct between these planar macromolecules. A self-consistent mechanism for the intercalation reaction has been postulated to explain the following observations: (i) for adduct pressures p⩾l torr the initial rate of reaction is proportional to p; and (ii) for p < 1 torr this rate varies as p 6. The latter observation indicates that cooperative phenomena involving six adduct molecule...