We have demonstrated a lamp-based atomic absorption detection system at 120 nm for monitoring atomic nitrogen generation in microwave discharge. Atomic nitrogen Aux and dissociation ratio were evaluated by the atomic absorption. Delivery of atomic nitrogen with a quartz tube was investigated. By suppressing the recombination of the atomic nitrogen with the Teflon insert, the delivered atomic nitrogen flux was enhanced by a factor of 3-10. At a microwave power of 300 W, an atomic flux of 5 x 10(16) cm(-2) s(-1), sufficient for growth of nitride thin films, was achieved. A model of recombination was used for explaining the experimental results, a maximum dissociation ratio of similar to 2% at the plasma region was estimated based on the measured atomic nitrogen densities.