Mechanism of chemiluminescence reaction between hypobromite and ammonia or urea

The reaction kinetics, the chemiluminescence spectra, the products, and the lifetimes of emission species for the chemiluminescence reaction between hypobromite and ammonia or urea in an alkaline aqueous solution were investigated. Results show that the reaction mechanism for ammonia chemiluminescence is different from that for urea. The reaction of ammonia and hypobromite produces NO2 in the gaseous phase and NO2- in solution; however, the reaction of urea and hypobromite does not. For the reaction of ammonia and hypobromite, chemiluminescence intensity obeys 1.5 order kinetics for hypobromite concentration when ammonia is in excess, but the reaction of urea and hypobromite obeys second order kinetics for hypobromite when urea is in excess. The spectrum of the chemiluminescence from the ammonia and urea with hypobromite shows a maximum intensity at 710, and at 510 nm, respectively. The chemiluminescence lifetimes of the emission species were 0.056 and 0.092 s for the reaction of ammonia and the reaction of urea, respectively. The chemiluminescence species of the reaction between hypobromite and ammonia seems to be excited NO2, that for urea seems to be excited N-2.