Infrared spectrum of the nitrosyl chloride monomer and dimer in solid nitrogen: Temperature-induced mobility of nitrosyl chloride

Experimental investigations at different temperatures of the infrared spect ra of nitrosyl chloride trapped in a nitrogen matrix allow identification o f the ClNO dimer and a next nearest neighbor pair. At 21 K, the pair transf orms irreversibly in monomer and also in dimer according to the ClNO initia l concentration, whereas at 26 K, the monomer transforms to dimer. On the b asis of kinetic studies, these observations have been interpreted by the ex istence of two distinct motions of the ClNO molecule in the nitrogen matrix : the first at short range with an activation energy of around 4 kJ mol(-1) , and the second at long range leading to the formation of (ClNO)(2) with a n activation energy of around 7.5 kJ mol(-1).