Interaction of atomic nitrogen with electronically excited molecular oxygen: a theoretical study
Under conditions of violation of the thermodynamic equilibrium between the internal degrees of freedom of particles, the kinetics of the ongoing physicochemical processes can differ significantly from the equilibrium case. One of the important reactions responsible for the formation of nitrogen oxides in air is the reaction of a nitrogen atom with an oxygen molecule, which can be in the ground state as well as in the electronically excited states under the influence of a nonequilibrium electric discharge, resonant laser radiation or behind the front of a strong shock wave. Quantum chemical calculations were performed using the extended multi-configuration quasi-degenerate perturbation theory to study the reaction of the interaction of a nitrogen atom with an electronically excited molecule O2 in the sigma electronic states a and b. Energetically favorable reaction paths, minimum energy crossing points, and the corresponding quenching channels were found. It was shown that the activation barrier of the reaction nitrogen atom with singlet delta oxygen is 2.3 times larger than the barrier of the reaction of a ni-trogen atom with O2 in the ground state, however, for an accurate estimate of the constant of this process it is also necessary to take into account the probability of a nonadiabatic transitions. It was shown for the first time that the reaction of atomic nitrogen and singlet sigma oxygen leads to the formation of a molecule NO and an atom O. Besides, the quenching singlet sigma oxygen on atom N is also possible. In the future, the rate constants of these processes will be estimated within the variational and non-adiabatic transition state theories
В условиях нарушения равновесия между внутренними степенями свободы частиц кинетика протекающих процессов может существенно отличаться от равновесного случая. Одной из важных реакций, ответственных за образование оксидов азота в воздухе, является реакция атома азота с молекулой кислорода, который в условиях воздействия неравновесного электрического разряда, резонансного лазерного излучения или за фронтом сильной ударной волны может находиться не только в основном, но и в электронно-возбужденных состояниях. Для изучения реакции взаимодействия атома азота с электронно-возбужденной молекулой O2 в синглетных электронных состояниях a и b проведены квантово-химические расчеты с использованием расширенной многоконфигурационной квазивырожденной теории возмущения второго порядка. Были обнаружены энергетически выгодные пути реакции, а также точки межсистемных переходов с минимальной энергией и соответствующие им каналы тушения. Показано, что активационный барьер реакции атома азота с синглетным дельта-кислородом больше, чем барьер реакции атома азота с O2 в основном состоянии в 2.3 раза, однако для точной оценки константы данного процесса необходимо также учитывать вероятность неадиабатических переходов. Впервые было показано, что реакция атомарного азота и синглетного сигма-кислорода приводит к образованию молекулы NO и атома O. Помимо этого, также возможен процесс тушения синглетного сигма-кислорода на атоме N. В дальнейшем планируется провести оценку констант скорости данных процессов в рамках вариационной и неадиабатической теорий переходного состояния
азот, кислород, неравновесная разрядная плазма, электронное возбуждение, квантовая химия
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