Cross-relaxation of hydrogen atoms adsorbed on a molybdena–silica catalyst

Abstract

E.p.r. spectra of adsorbed hydrogen atoms generated during photoreduction of molybdena-silica catalysts in H₂ at 77 K or below show an anomalous intensity ratio for the hyperfine components. It has been shown that this is due to cross-relaxation between the hydrogen atoms and Mo⁵⁺ cations produced during photoreduction. Estimates are made of the cross-relaxation rate and the correlation distance between the two paramagnetic species.