A plasma‐mixing device in which a helium plasma beam is crossed with a molecular nitrogen beam was used to measure the branching ratio of the excitation of individual vibrational levels of theB2&Sgr; electronic state of the molecular nitrogen ion in charge‐transfer collisions between He+2ions and ground‐state N2molecules. The branching ratio of the excitation of individual vibrational levels of theC3&Pgr; electronic state of the neutral nitrogen molecule due to the resonant energy‐transfer collisions between argon metastables and ground‐state nitrogen molecules was also measured using a plasma beam of a mixture of argon and helium. These results allow comparison of our measurements with results obtained using other techniques.