X-ray radiation damage provides a serious bottle neck for investigatingmicroseconds to s dynamics on nanometer length scales employing X-ray photoncorrelation spectroscopy. This limitation hinders the investigation of realtime dynamics in most soft matter and biological materials which can tolerateonly X-ray doses of kGy and below. Here, we show that this bottleneck can beovercome by low dose X-ray speckle visibility spectroscopy. Employing X-raydoses of 640 Gy to 8 kGy and analyzing the sparse speckle pattern of countrates of 10-2 per pixel and below we follow the slow nanoscale dynamics of anionic liquid (IL) at the glass transition. At the pre-peak of nanoscale orderin the IL we observe complex dynamics upon approaching the glass transitiontemperature TG with a freezing in of the alpha relaxation and a multitude ofmilli-second local relaxations existing well below TG. We identify this fastrelaxation as being responsible for the increasing development of nanoscaleorder observed in ILs at temperatures below TG.
展开▼
