Determiniation of Band Oscillator Strengths of Atmospheric Molecules from High Resolution VUV Cross Section Measurements

来自太阳的光驱动着大气的化学变化。 这种化学反应是由各种物质吸收光而引发的。 气. 此外，每种气体吸收各种颜色， 光（电磁波谱）的频率， 不同的效率。 这种效率是一个重要因素， 一种颜色能渗透到大气层的多深， 因此，在什么样的高度， 会很重要 在高层大气中，非常有活力 代表真空的光子（高频颜色） 电磁波谱的紫外（VUV）区域是 被氧分子微弱吸收， 大气中的气体。 因此分子氧很重要 来移除这些光子。 吸收效率 (or截面）的氧在该光谱区域中是 由于复杂的 被称为舒曼-龙格吸收谱线的窄吸收线系统 乐队. 精确的测量需要仔细的工作， 电磁波谱的分辨率。 其他重要 在高层大气中的过程涉及吸收 VUV通过氮氧化物（NO），其同样具有复杂的 吸收截面不充分的光谱 知道的 该项目是一个研究的延续， 在Grant ATM-8318960下的NSF。 真空紫外截面测量 氧气和氮氧化物的排放将在最近进行， 构建的真空紫外傅里叶变换光谱仪，可以实现 测定所需的高光谱分辨率 分子谱带的绝对截面具有明显的 旋转结构 横截面应在以下位置获得： 温度为78 K和300 K。 这些数据将使更多 精确模拟高能光的传输 比目前可能的更高， 将有利于大气化学的各种研究工作 和aeronomy。

Light from the sun drives the chemistry of the atmosphere. The chemistry is initiated by the absorption of light by various gases. Furthermore, each gas absorbs the various colors (frequencies) of the light (the electromagnetic spectrum) with varying efficiency. This efficiency is an important factor for how deeply into the atmosphere a given color can penetrate and consequently at what altitudes a particular chemical pathway will be important. In the upper atmosphere, very energetic photons (colors of high frequencies) representing the vacuum ultraviolet (VUV) region of the electromagnetic spectrum are weakly absorbed by molecular oxygen, the second most abundant gas in the atmosphere. Molecular oxygen is therefore important for the removal of these photons. The absorption efficiency (or cross section) of oxygen in this spectral region is particularly difficult to measure because of a complicated system of narrow absorption lines known as the Schumann-Runge bands. Accurate measurements require careful work with high resolution of the electromagnetic spectrum. Other important processes in the upper atmosphere involve the absorption of VUV by nitrogen oxide (NO) which similarly has a complicated spectrum whose absorption cross sections are inadequately known. This project is a continuation of research supported by NSF under Grant ATM-8318960. VUV cross section measurements of oxygen and nitrogen oxide will be performed with a recently constructed VUV Fourier transform spectrometer that can achieve a high spectral resolution necessary for determination of absolute cross sections of molecular bands possessing distinct rotational structure. Cross sections are to be obtained at temperatures of 78K and 300K. These data will allow more accurate modeling of the transmission of energetic light through the upper atmosphere than is currently possible and will benefit various research efforts in atmospheric chemistry and aeronomy.