Direct measurements of. both the dissociation fraction and the atom flux have been carried out for the first time to characterize a radio frequency (rf) atomic nitrogen source. The measurements have been made over a range of Source pressures and rf powers. Dissociation fractions of up to 0.4 and atomic nitrogen fluxes of up to 0.85x 10(18) atom s(-1) were obtained. In addition these results have been correlated with spectroscopic measurements of the ratios of atomic and molecular optical emissions from the source plasma in order to provide a way of estimating in situ the atomic flux.