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，科学界对中层大气中发生的复杂光化学反应有了更多的认识。在大约40公里及以上的高度，分子氧（O2）被紫外线分解，形成的氧原子与O2反应产生臭氧（O3）。这些反应序列产生了保护地球表面免受有害紫外线辐射的臭氧层。人们对高空飞行的飞机、向大气释放氯氟烃以及农业向大气释放一氧化二氮等人类活动可能破坏中层大气中的臭氧的担忧，激发了人们对臭氧光化学的兴趣。自20世纪70年代初以来，进行了实验室和实地调查，以便更好地确定平流层化学和人类干扰这一微妙系统的潜力。在这些研究过程中发现，中层大气中的臭氧明显富含重氧同位素（即，比最常见的氧原子重的氧原子）。臭氧层中氧同位素异常分布的这一发现一直是科学质疑和辩论的主题，因为目前关于臭氧产生和破坏的机制和速率的知识并不能预测观测到的臭氧同位素组成。这是NSF在ATM-资助下的更新支持

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-