NH2 RADICAL DETECTION BY NH(A) PHOTOFRAGMENT FLUORESCENCE

Hot NH2 radicals, which are initially generated in the ArF laser photo lysis of NH3, relax quickly to ambient temperature in collisions with Ar. They were subsequently detected by the fluorescence of the electro nically excited NH(A (3) Pi) photofragments emitting at 336 nm. The ph otolysis light source for the radicals was a cw Xe lamp at 147 nm. Thi s method makes it possible to monitor NH2 radicals for more than 0.2 s , as they slowly react with each other and diffuse out of the observat ion volume. The detected NH2 concentrations ranged from similar to 10( 13) to similar to 10(15) cm(-3).