| The chemistry in solution phase, which I will largely focus on in this seminar, is a very important field of research as it is a natural environment for the majority of life processes. Studying this environment with X-rays is ideal since X-rays can penetrate bulk samples and hence reveal the elementary principles driving chemical reactions. Because the atoms are so small (~10-10 m), and they take very little time to change positions (~10-13 s) their direct observation has eluded scientists for decades. This feat is now accomplished with the pump-probe method, where a -Y´pumpˇ laser triggers a reaction and a delayed ´probeˇ pulse captures a snapshot of the transient species. Technological innovations in synchrotron instrumentation and the development of novel data analysis have made it possible to track increasingly complex reactions in solution by time-resolved diffraction to a temporal and spatial resolution of 100 ps and 0.001 Ĺ, respectively. For instance, the photodissociation reaction of C2H4I2 in methanol was recently investigated by this technique and the data analysis revealed a rather complex reaction pathway comprising a long purported bridged C2H4I radical, a linear isomer C2H4I-I, and the end-product C2H4 + I2. Moreover with TRXD, the properties and structures of elemental liquids can be studied too. In addition, we further extended this technique to study protein structural dynamics in solution. We obtained time-resolved WAXS (wide-angle x-ray scattering) data from heme proteins such as myoglobin and hemoglobin and preliminary analysis showed that the 3D structural changes of proteins can be monitored by time-resolved x-ray diffraction even in solution. Username: ihee57 Do you want a computer account to be created for the time of your stay? It is necessary in order to have internet access if you do not bring your own laptop. If yes, please provide a username in the field above. |
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