Figure 8
From: X-ray diffraction of metastable structures from supercooled liquid hydrogen
Schematic of the experimental setup showing 11.2 keV LCLS X-ray beam scattering from a supercooled \(H_{2}\) microjet. The scattered photons are captured on a detector to angularly resolve the solid and liquid structure factors as a function of distance from the nozzle. A photodiode is placed in the backscatter geometry to measure the incoherent Compton background, and a fiber-delayed dual pulse optical laser, with a fixed 500 ns delay, is used to measure the microjet velocity, per scattering event, by the superposition of crystallites imaged on an OPAL camera. (Top) A visualization of the stacking sequence measured via the changes to the diffraction peaks as a function of time from the nozzle. (Bottom) Raw scattering data as a function of position from the nozzle, in counts, accumulated for \(\sim \)10 minute increments collected at 120 Hz pulse repetition rate. Single exposure inset shows diffraction from stacking faults (lines), and crystals (spots). The liquid to solid scattering ratio is large at a distance of 300 \(\mu \)m and decreases farther away from the nozzle.
