Low dose X-ray speckle visibility spectroscopy reveals nanoscale dynamics in radiation sensitive ionic liquids

Abstract

X-ray radiation damage provides a serious bottle neck for investigating μs to s dynamics on nanometer length scales employing X-ray photon correlation spectroscopy. This limitation hinders the investigation of real time dynamics in most soft matter and biological materials which can tolerate only X-ray doses of kGy and below. Here, we show that this bottleneck can be overcome by low dose X-ray speckle visibility spectroscopy. Employing X-ray doses of 22 kGy to 438 kGy and analyzing the sparse speckle pattern of count rates as low as 6.7x10-3 per pixel we follow the slow nanoscale dynamics of an ionic liquid (IL) at the glass transition. At the pre-peak of nanoscale order in the IL we observe complex dynamics upon approaching the glass transition temperature TG with a freezing in of the alpha relaxation and a multitude of milli-second local relaxations existing well below TG. We identify this fast relaxation as being responsible for the increasing development of nanoscale order observed in ILs at temperatures below TG.

7 pages, 5 figures

References in corpus (3)

• Theoretical perspective on the glass transition and amorphous materials
• Speckle-visibility spectroscopy: A tool to study time-varying dynamics
• Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

Cited by in corpus (5)

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• Split-pulse X-ray photon correlation spectroscopy with seeded X-rays from X-ray laser to study atomic-level dynamics
• Beam-induced Atomic Motion in Alkali Borate Glasses
• Heterogeneous dynamics in a polymer solution revealed through measurement of ultraslow convection
• Using low dose X-ray Speckle Visibility Spectroscopy to study dynamics of soft matter samples