Thurn-Albrecht T, Zontone F, Grübel G, Steffen W, Müller-Buschbaum P, Patkowski A
Physikalisches Institut, Albert-Ludwigs-Universität, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Sep;68(3 Pt 1):031407. doi: 10.1103/PhysRevE.68.031407. Epub 2003 Sep 22.
We performed x-ray photon correlation spectroscopy on a model suspension of colloidal particles using x rays of three different energies, namely, 8 keV, 13.5 keV, and 19 keV. The observed reduction in the degree of coherence with increasing x-ray energy, as measured by the contrast of the correlation functions, is consistent with theoretical estimates. We show that it is well possible and under certain circumstances even advantageous to perform experiments with coherent x rays at these higher energies. We argue that the reduced absorption may not only allow for thicker samples but also for longer acquisition times because of the reduced radiation damage, thus outweighing in many cases the effect of the reduced coherent flux. The use of higher energy x rays for photon correlation spectroscopy can therefore lead to a substantial increase in the signal-to-noise ratio and constitutes a promising option for future experiments on samples of polymeric or biological origin.
我们使用三种不同能量的X射线，即8 keV、13.5 keV和19 keV，对胶体颗粒的模型悬浮液进行了X射线光子相关光谱分析。通过相关函数的对比度测量，观察到随着X射线能量增加，相干度降低，这与理论估计一致。我们表明，在这些较高能量下用相干X射线进行实验是完全可行的，并且在某些情况下甚至是有利的。我们认为，吸收减少不仅可以使用更厚的样品，而且由于辐射损伤减少，还可以延长采集时间，因此在许多情况下超过了相干通量减少的影响。因此，在光子相关光谱中使用更高能量的X射线可以显著提高信噪比，对于未来对聚合物或生物源样品的实验来说是一个很有前景的选择。
