The Study of Oxygen Isotopic Fractionation Mechanisms in Ozone Formation and Measurement of these ratios in air O2 at ultrahigh precision.

在过去的十年里，科学界对在中层大气中发生的复杂的光化学反应有了更多的了解。在大约40公里及以上的高空，分子氧(O2)被紫外光分解，形成的氧原子与O2反应生成臭氧(O_3)。这些反应序列产生了臭氧层，保护地球表面免受有害的紫外线辐射。由于担心人类活动，如高空飞行的飞机、向大气中释放氯氟烃以及农业向大气中释放一氧化二氮可能导致中层大气中的臭氧破坏，人们对臭氧光化学产生了兴趣。自20世纪70年代初以来，为了更好地确定平流层化学和人类扰乱这一微妙系统的潜力，S进行了实验室和野外调查。在这些研究过程中，人们发现，中间大气中的臭氧明显富含重氧同位素(即比最常见的氧原子更重的氧原子)。这一在臭氧层中异常分布的氧同位素的发现一直是科学质疑和争论的主题，因为目前关于臭氧产生和破坏的机制和速度的知识并不能预测观测到的臭氧的同位素组成。这是美国国家科学基金会在自动取款机资助下的续签-

In the past decade the scientific community has become more aware of the complex photochemical reactions which occur in the middle atmosphere. At an altitude of about forty kilometers and above molecular oxygen (O2) is dissociated by ultraviolet light and the oxygen atoms formed react with O2 to create ozone (O3). These reaction sequences are responsible for creation the layer of ozone which shields the earth's surface from harmful ultraviolet radiation. Interest in the ozone photochemistry has been spurred by concerns that human activities such as high flying aircraft, chlorofluorocarbon release to the atmosphere, and atmospheric release of nitrous oxide by agriculture might result in the destruction of ozone in the middle atmosphere. Since the early 1970's laboratory and field investigations have been carried out in order to better define stratospheric chemistry and man's potential of perturbing this delicate system. In the course of these studies it has been discovered that ozone in the middle atmosphere is apparently enriched in the heavy oxygen isotopic (i.e., oxygen atoms which weigh more than the most common oxygen atoms.) This finding of anomalously distributed oxygen isotopes in the ozone layer has been the subject of scientific questioning and debate since current knowledge about the mechanisms and rates of ozone production and destruction does not predict the observed isotopic composition of ozone. This is a renewal of NSF support under the grant ATM-