Laser-induced fluorescence studies of vibrational and rotational relaxation in a supersonic molecular beam of bromine monochloride

Using time-of-flight and laser-induced fluorescence methods, the efficiencies of rotational and vibrational relaxation of BrCl by Cl2 have been studied by measuring the final translational, rotational and vibrational temperatures of a supersonic beam of BrCl seeded in Cl2. Collision numbers, Z R ∼ and Z v ∼ 28, have been obtained. Rotational relaxation is found to occur at a rate close to gas kinetic. Vibrational relaxation appears to be very efficient at the low temperatures of the beam and this is attributed to additional relaxation being achieved due to the formation of metastable orbiting complexes.