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

O2 与 N2 的赫茨伯格态反应 - 平流层 N2O 的可能来源

• 批准号: 9523356
• 负责人: Richard Copeland
• 金额: $ 3万
• 依托单位: SRI International
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-01 至 1997-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9523356&HistoricalAwards=false
• 关键词: O2; Herzberg; State; Reaction; N2

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.

9523356在这个项目中，我们将研究分子氧的各个激发态(特别是赫兹伯格态)与分子氮反应生成一氧化二氮的过程。这一反应有可能成为大气中一氧化二氮的来源。对决定一氧化二氮大气高度分布的汇和源术语的一般理解仍在发展中。尽管大气中一氧化二氮的大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，氧的赫兹伯格态的消失相当快，至少对于这些态的较高振动水平，氮是地球大气中的主要猝灭剂。赫兹伯格态在平流层上层和中间层下层通过吸收太阳辐射而产生，在中间层上层和热层下层通过氧原子复合产生。要对平流层一氧化二氮的预算产生重大影响，只需要很小的反应产率。将进行实验室实验，在含氧和氮的封闭系统中，氧分子将被UV激光激发到三个赫兹伯格态之一的特定振动水平。在混合物暴露在共振光下数分钟至数小时后，将使用极其灵敏的调频二极管激光光谱分析技术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，将建立其产量的上限，从而消除对该反应体系的进一步猜测。