Atmospheric Oxygen Photoabsorption

小行星9217584 地球大气层的光化学反应主要由双原子和三原子形式的分子氧所控制。 氧气吸收了大部分的太阳辐射在紫外线为100至240纳米，导致臭氧的形成。 氧气吸收光谱的结构性，以及随之而来的吸收截面的大范围变化，意味着紫外线辐射在很宽的高度范围内被吸收。 一些波长在100公里以上被吸收，而另一些则下降到40公里以下，在那里它们可以引发从地面向上扩散的人类物种的化学反应。 因此，臭氧产生和大气中其他太阳诱导光化学的定量建模需要详细了解臭氧的吸收光谱、紫外太阳辐射的光谱分布（包括太阳周期变化）以及通过大气的辐射传输。 最近在实验室和其他地方的研究表明，现有的数据和机械的理解是远远不够的。 该项目涉及实验，理论和建模研究，以提高我们对大气中紫外线辐射吸收的认识。 着重讨论了四个主要问题：（1）臭氧Schumann-Runge带系中各上振动能级转动和精细结构分辨线宽的测量;（2）从理论上分析了臭氧态与其四个预离解态之间的相互作用，根据实验线宽，（3）将现有的太阳能沉积模型与将实验线宽折叠成真实太阳光谱的模型进行比较;（4）臭氧在A-X、A '-X和c-X赫兹伯格带的线分辨绝对光吸收截面的测量。

9217584 Slanger The photochemistry of the earth's atmosphere is dominated by molecular oxygen in its diatomic and triatomic forms. Oxygen absorbs much of the solar radiation in the ultraviolet for 100 to 240 nm, leading to the formation of ozone. The structured nature of the oxygen absorption spectrum, and the consequent wide variations in the absorption cross section, mean that uv radiation is absorbed over a wide range of altitudes. Some wavelengths are absorbed above 100 km, while others descend below 40km, where they can initiate chemistry in anthropogenic species diffusing upward from the ground. Thus quantitative modeling of ozone production and other solar-induced photochemistry in the atmosphere requires detailed knowledge of the absorption spectrum of ozone, the spectral distribution of ultraviolet solar radiation (including solar cycle variations), and radiative transport through the atmosphere. Recent research in laborators and elsewhere suggests that the existing data and mechanistic understanding are far from adequate. This project involves experimental, theoretical, and modeling research to improve our knowledge of the absorption of ultraviolet radiation in the atmosphere. Four main topics are emphasized: (1) measurement of rotational and finestructure resolved linewidths for each upper vibrational level in the ozone Schumann-Runge band system; (2) theoretical analysis of the interactions between the ozone state and its four predissociating states, based on the experimental linewidths, (3) comparison of current models for solar energy deposition with that resulting from folding the experimental linewidths into the true solar spectrum; and (4) measurement of line-resolved absolute photoabsorption cross sections for ozone in the A-X,A'-X, and c-X Herzberg bands.