O2 Herzberg State Reaction with N2 - A Possible Source of Stratospheric N2O

小行星9523356 本课题研究通过分子氧的个别激发态（具体而言是赫兹伯格态）与分子氮的反应生成一氧化二氮。这种反应可能会提供一氧化二氮的大气来源。对决定一氧化二氮大气高度分布的汇和源的一般理解仍在发展。虽然大气中的一氧化二氮主要来自土壤和人类活动，但也可能有平流层来源。最近对平流层一氧化二氮的同位素测量表明，它可能不是全部在地球表面形成的。这个SRI研究小组进行的实验室实验表明，在与氮的碰撞中，氧赫兹伯格态的去除是相当迅速的，至少对于这些态的较高振动能级，氮是地球大气中的主要猝灭剂。赫茨伯格态是在平流层上部和中间层下部通过吸收太阳辐射产生的，在中间层上部和热层下部通过氧原子复合产生的。要对平流层的一氧化二氮收支产生重大影响，只需要很小的反应产率。 将进行实验室实验，在含有氧和氮的封闭系统中，用紫外激光将氧分子激发到三个赫兹伯格态之一的特定振动能级。在混合物暴露在共振光下几分钟到几个小时后，将使用频率调制二极管激光光谱学的极其敏感的技术来分析产生的气体中的一氧化二氮。如果没有检测到一氧化二氮，将建立其生产的上限，消除进一步推测该反应系统。

9523356 Copeland In this project, the production of nitrous oxide from the reaction of individual excited states (specifically, Herzberg states) of molecular oxygen with molecular nitrogen will be investigated. This reaction could potentially provide an atmospheric source of nitrous oxide. The general understanding of the sink and source terms that determine the atmospheric altitude profile of nitrous oxide is still evolving. Although the major fraction of atmospheric nitrous oxide comes from the soil and from anthropogenic activity, there may also be a stratospheric source. Recent isotopic measurements of stratospheric nitrous oxide suggest that all of it may not be formed on the earth's surface. Laboratory experiments performed by this SRI research group have demonstrated that the removal of the oxygen Herzberg states in collisions with nitrogen is quite rapid, and that at least for the higher vibrational levels of these states, nitrogen is the dominant quencher in the terrestrial atmosphere. The Herzberg states are generated in the upper stratosphere and lower mesosphere by absorption of solar radiation, and in the upper mesosphere and lower thermosphere by oxygen atom recombination. To have a significant impact on the stratospheric nitrous oxide budget, only a very small reaction yield would be required. Laboratory experiments will be performed where oxygen molecules will be excited to a specific vibrational level of one of the three Herzberg states with a UV laser in a closed system containing oxygen and nitrogen. After the mixture is exposed to the resonant light for minutes to hours, the resulting gases will be analyzed for nitrous oxide using the extremely sensitive technique of frequency-modulated diode laser spectroscopy. If no nitrous oxide is detected, an upper limit for its production will be established, eliminating this reaction system from further speculation.