High efficiency multichannel collimator for structural studies of liquids and low-Z materials at high pressures and temperatures

Abstract

A high efficiency multichannel collimator (MCC) device has been developed at the high pressure beamline ID27 of the European Synchrotron Radiation Facility to drastically reduce the x-ray background from the sample environment in the Paris-Edinburgh press. The main technical difficulty, which resides in the minimum slits size achievable using the classical mono-bloc design, has been resolved using an original concept based on a set of independent slits. Then, a very small slit size of 50 μm was manufactured resulting in a great improvement of the signal to background ratio. In addition, the transfer function of the MCC has been measured using the x-ray diffusion signal of a metal doped glass and efficiently applied to correct the raw data. The potential of this new device is illustrated in two challenging examples: iron-sulfur liquid structures and C(60) polymerization process at high pressure and high temperature.

Toward comprehensive studies of liquids at high pressures and high temperatures: Combined structure, elastic wave velocity, and viscosity measurements in the Paris–Edinburgh cell

“…The tight control of collimation depth is essential to obtain reliable structure data for liquids as the signals are diffused and weak. For monochromatic beam diffraction with a large area detector, a multichannel Soller slit has been developed to implement the collimation depth control Morard et al, 2011].…”

Use of a multichannel collimator for structural investigation of low-Z dense liquids in a diamond anvil cell: Validation on fluid H2 up to 5 GPa

“…The two sets of slits are made from tungsten carbide blades supported by a stainless steel frame. 12 This permits a smaller inner slit width of 50 μm (200 μm for the outer slits), reducing the diffracting volume seen by the detector and thus making them more suitable for the small sample sizes. The outer slit width is defined so as to optimize the signal-to-noise ratio.…”

“…10 This solution was implemented to fit the constraints of the Paris-Edinburg (PE) large volume press and it is now routinely used on beamline ID27 of the European Synchrotron Radiation Facility (ESRF). 11,12 Here, we present our adaptation of the MCC device for the DAC based on a modification of the PE-MCC design. Because of the small dimensions and sample volume in the DAC, a careful alignment procedure between the MCC slits and the DAC also had to be implemented.…”

Structure of liquid carbon dioxide at pressures up to 10 GPa

“…The MCC, inspired from the original design of Ref. [33], is composed of two sets of concentric slits and is positioned between the sample and the 2D detector in order to isolate a small diffracting volume around the sample [34]. This technique was successfully applied to samples of liquid hydrogen at pressures up to 5 GPa [35].…”