Construction of Simultaneous Observation System of Time-Resolved ESR and Nanosecond Transient Absorption Spectra

建立了用于时间分辨ESR光谱的纳秒激光光解系统和光学透射腔。我们将该系统应用于几个光化学反应，测量了短寿命中间体的瞬时吸收光谱和时间分辨ESR光谱。目前的研究清楚地表明，该体系在光化学中发挥着重要作用，因为从这些光谱中获得的信息是相辅相成的。纳秒激光光解系统。为了测量激光激发产生的短寿命激发三重态和自由基中间体的瞬时吸收光谱，建立了一个纳秒激光光解系统。我们获得了所需的能力以达到我们的目的。透射式微波腔。我们制备了一个带有窗口(5Phi)的透射腔，用于激光光解。卸载Q值大于3000。该腔可以通过光纤与跃迁吸收光谱相连接。Ph…对反应机理和动力学进行更多的耳化学研究。研究了在给电子剂或供氢剂存在下，环氧酮类化合物的光化学。在胺存在下，用瞬时吸收法观察到环氧酮的阴离子自由基。测定了自由基的寿命不到1微秒。虽然瞬时吸收法没有检测到开环产生的碳中心自由基，但时间分辨ESR谱清楚地测量到了它。因此，我们可以用这个体系来确定光化学链反应的机理。当自由基呈现二级衰减时，通常很难确定摩尔消光系数。就这一目的而言，目前的制度非常有用。我们可以测定由光敏二聚体的激光光解产生的短暂的吡啶自由基的消光系数。还观察到了邻硝基联苯的时间分辨三重-三重吸收光谱。较少

A nanosecond laser photolysis system and an optical transmission cavity for time-resolved ESR spectroscopy were constructed. We applied the system for several photochemical reactions to measure transient absorption and time-resolved ESR spectra of the short-lived intermediates. The present study clearly shows that this system plays an important role in photochemistry, since the informations obtained from these spectra are complements each of the other.1. Nanosecond laser photolysis system. For measurements of transient absorption spectra of the short-lived excited triplet states and radical intermediates generated from laser excitation, a nanosecond laser photolysis system was constructed. We obtained desired capability for our purpose.2. Transmission microwave cavity. We prepared a transmission cavity equipping with a window (5 phi) for laser photolysis. Unloaded Q value is large than 3000. The cavity is able to connect to the transition absorption spectroscopy by optical fibers.3. Ph … More otochemical studies on the reaction mechanism and dynamics. Photochemistry of epoxyketbne derivatives was studied in the presence of electron or hydrogen donating reagents. In the presence of amines, the anion radical of epoxyketone was observed by transient absorption method. The life-time of the radical was determined to be less than 1mus. Although the carbon centered radical generated from the ring opening was not detected by the transient absorption method, it was clearly measured by time-resolved ESR spectroscopy. Therefore, we can determine the photochemical chain reaction mechanism by using the present system.When free radical shows second order decay, it is usually difficult to determine the molar extinction coefficient. The present system is very useful for the purpose. We can determine the extinction coefficients of shortlived pyridinyl radicals generated from the laser photolysis of the photosensitive dimers. The time-resolved triplet-triplet absorption spectrum of o-nitrobiphenyl was also observed. Less