Аннотация:Results of an experimental study of singlet oxygen formation in N2:O2 mixtures in a non-self-sustained discharge plasma produced by an electron beam are examined. Two mechanisms of singlet oxygen formation are identified. The first mechanism involves direct excitation of oxygen molecules by plasma electrons; this mechanism is not related to the level of vibrational excitation of nitrogen molecules or with the O2:N2 ratio. The second mechanism is thought to be related to energy transfer (possible, indirect) from nitrogen to oxygen.