Differential Excitation Cross Section Measurements of O3 by Electron Impact: A Search for Ozone Excited Electronic States

PIs建议用角分辨电子散射光谱对O3的电子结构和振动结构进行详细的研究。他们认为，必须更好地描述电子状态，以便开始适当地评估臭氧在地球大气中的化学作用、辐射转移和非局部热力学平衡（non-local thermodynamics equilibrium, non-LTE）效应。pi计划重现Swanson和Celotta 15年前的电子能量损失谱，提高灵敏度、能量分辨率和角度覆盖范围，并扩展测量范围，包括电子和振动激发截面的测定。Swanson和Celotta的结果虽然是开创性的，但在灵敏度和明确的特征分配方面是边缘的；然而，它仍然是有争议的低洼亚稳态臭氧能量学的唯一切实的实验证据。前提是这些态可能参与O + O2重组序列，因此可能是O3在平流层、中间层和热层光化学中的重要能量载体。

The PIs propose to conduct a detailed study of the electronic and vibrational structure of O3 by angle-resolved electron scattering spectroscopy. They assert that the electronic states must be better characterized in order to begin a proper assessment of the role of ozone in the chemistry, radiative transfer, and non-local thermodynamic equilibrium (non-LTE) effects in the terrestrial atmosphere. The PIs plan to reproduce the 15-yr-old electron energy loss spectra of Swanson and Celotta, with improved sensitivity, energy resolution, and angular coverage, and to extend the measurements to include determinations of electronic and vibrational excitation cross sections. The Swanson and Celotta result, though pioneering, is marginal in sensitivity and definitive feature assignments; however it remains the only tangible experimental evidence for the energetics of the controversial low-lying metastable states of ozone. The premise is that these states may participate in the O + O2 recombination sequence, and thus could be significant energy carriers in the photochemistry of O3 in the stratosphere, mesosphere, and thermosphere.