Two-photon absorption laser-induced fluorescence of atomic nitrogen by an alternative excitation scheme

A two-photon absorption laser-induced fluorescence (TALIF) scheme to monitor ground-state atomic nitrogen is described. Excitation at 207 nm to the (3p)S-4(3/2)o upper state is demonstrated to be superior to the traditional 211 nm excitation to (3p)D-4(7/2)o. Most Striking is the low quenching rate of the upper (3p)S-4(3/2)o State by N-2 at k(q) = 6.7(9) x 10(-11) cm(3) s(-1), nearly an order of magnitude lower than the traditional technique. The two-photon excitation rate at 207 nm is also measured to be a factor of 3.5 greater than the traditional scheme. The results suggest that the 207 nm excitation scheme should be employed in future N-atom diagnostic work. (C) 1998 Published by Elsevier Science B.V. All rights reserved.