At night at mid-latitudes the sources of N(2D) in the F region are reduced to the dissociative recombination of NO+. The only important sinks are quenching by atomic oxygen and electrons. As a result, a photochemical study made in the nighttime is greatly simplified in comparison with one made in the daytime. At night, however, the optical emission at 5200 ¿ resulting from the transition from N(2D) to N(4S) is difficult to measure because of the low intensities. By combining ground-based measurements of I 5200 with coincident satellite observations of neutral and ion densities and temperatures and the shape of the 5200 ¿ emission profile, we are able to relate the rate of quenching by atomic oxygen and the efficiency of production of N(2D) to the rate of quenching by electrons. Assuming a rate of 1.0¿10-9 (Te/300)0.5 cm3 s-1 for quenching by electrons, we obtain 1.5--2.5¿10-12 cm3 s-1 for quenching by atomic oxygen and an efficiency of (0.8--1.0) ¿30% for the production of N(2D) by dissociative recombination of NO+. The recent laboratory determination of the rate coefficient for the recombination of NO+ of 4.3¿10-7(Te/300)-0.37 cm3 s-1 is found to be in good agreement with the measured ion densities.