Fig. 2.

Methodology for freezing under pressure. (A) Detail of sample in the pressure bomb. A borosilicate capillary is modified by the addition of a magnetic collar near the top. A silicone piston separates the sample (orange) from the ethanol pressurization fluid (red) that fills the stainless steel pressure bomb. (B) The bomb is connected to the pressure intensifier with the lower portion immersed in dry ice/ethanol at 200 K. The sample is held at the top of the bomb using the magnet where the temperature is controlled at 298 K during pressurization. (C) Under pressure, the sample is moved quickly to the bottom of the bomb, triggering rapid cooling to 200 K. (D) The bomb is depressurized, disconnected from the pressure intensifier, and submerged in the dry ice/ethanol bath. (E) The sample capillary is transferred to liquid nitrogen (blue) for cooling to 77 K in preparation for DEER data acquisition at 80 K.