Carbonyl oxides as reactive intermediates in the lower atmosphere and the effect of optical excitation

多年来，羰基氧化物(“Criegee”)被确定为低层大气中的重要活性中间体，其作用--特别是在电子激发时--仍未得到很好的了解。在该项目中，将结合精确的电子结构计算和耦合势能面上的多维波包传播，从理论上研究电子激发的羰基氧化物的光谱和光物理。因此，即使是最小的CH2OO体系的紫外光谱也需要澄清模糊的实验结果和相互矛盾的解释。除了光谱强度分布外，相关(主要是单重态)激发态的内部转换动力学也令人感兴趣。从这些研究和相关研究的结果中，预计将出现一幅关于光激发后这些羰基氧化物动力学的连贯图景，这将为更好地理解低层大气(对流层)中的光化学基本过程提供基础。如上文所述，为了得出决定性的结果，该项目将重点放在碳原子最多为三个的羰基氧化物上；多年来，后一种物种也要进行密集的实验研究。

For several years carbonyl oxides ("Criegees") are established as important reactive intermediates in the lower atmosphere whose role - especially upon electronic excitation - is nevertheless not well understood. In the project the spectroscopy and photophysics of electronically excited carbonyl oxides are to be investigated theoretically by a combination of accurate electronic structure computations and multidimensional wavepacket propagations on coupled potential energy surfaces. Thereby ambiguous experimental results and conflicting interpretations of the UV spectra of even the smallest system CH2OO are to be clarified. In addition to the spectral intensity profile also the internal conversion dynamics of the relevant (mostly singlet) excited states is of interest. From the results of these and related studies a coherent picture of the dynamics of these carbonyl oxides after photoexcitation is expected to emerge, which should provide the basis of a better understanding of the photochemical elementary processes in the lower atmosphere (troposphere). To arrive at conclusive results, the project focusses - as already indicated above - on carbonyl oxides with up to three carbon atoms; for a number of years the latter species are also subject to intense experimental investigations.