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

在这个项目中，将研究从分子氧与分子氮的单个激发态（特别是赫茨伯格态）的反应中产生氧化亚氮。这一反应可能为大气提供一氧化二氮的潜在来源。对决定一氧化二氮大气高度分布的汇和源项的一般理解仍在不断发展。虽然大气中氧化亚氮的主要部分来自土壤和人为活动，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，它可能并不都是在地球表面形成的。这个SRI研究小组进行的实验室实验表明，在与氮的碰撞中，氧赫茨伯格态的去除相当迅速，并且至少对于这些状态的较高振动水平，氮是地球大气中主要的猝灭剂。在平流层上层和中间层下层由于吸收太阳辐射而产生赫茨伯格态，在中间层上层和下层热层由于氧原子复合而产生赫茨伯格态。要对平流层一氧化二氮收支产生重大影响，只需要非常小的反应产率。实验室实验将在含氧和氮的封闭系统中，用紫外激光将氧分子激发到三个赫茨伯格态之一的特定振动水平。将混合物暴露在谐振光下几分钟到几小时后，将使用极其灵敏的调频二极管激光光谱学技术分析产生的气体是否含有一氧化二氮。如果没有检测到氧化亚氮，则将确定其生产的上限，从而消除对该反应系统的进一步推测。

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.