Translational diffusion of chemically active species: carbenes and carbonyl oxides

The transient grating signals after photolysis of hexabromodiphenyldiazomethane and hexamethyldiphenyldiazomethane are investigated in benzene. The species grating signals under the oxygen purged condition are attributed to hexabromodiphenyl carbene (HBrC) and N2, while to carbonyl oxides and N2 in the presence of oxygen. Translational diffusion constants (D) of these chemically unstable species are determined. D of the carbene is found to be smaller than that of the parent molecule or the carbonyl oxide. D of the carbonyl oxide is close to that of the parent molecules.