Measurements of nitrogen atom density, by means of NO chemical titration, along with an evaluation of the densities of some excited species N-2(B, v = 11), N-2(B, v = 2), N-2(C, v = 0), and N-2(+)(B, v = 0), by means of a spectroscopic study of some bands of dinitrogen, are achieved along the flowing afterglow of a dinitrogen microwave plasma (2450 MHz) for several pressures. The concentrations obtained are in the following range. [N]similar to 10(+15), [N-2(B, 2)]similar to 10(+9)-10(+10), [N-2(B, 11)]similar to 10(+8) -10(+9), [N-2 (C, 0]similar to 10(+6)-10(+7), [N-2(+)(B, 0)]similar to 10(+6)-10(+8) (cm(-3)). From a kinetic study of the formation and decay of excited and charged species, an estimation of N-2(A, v), N-2(X, v), and N-2(+)(X) densities can be derived. [N-2(A, v)]similar to 10(+12), [N-2(X, v greater than or equal to 6)]similar to 10(+15)-10(+16), [N-2(X, v greater than or equal to 12)]similar to 10(+14)-10(+15), [N2+X)]similar to 10(+10) (cm(-3)).