Figure 1
From: Performance and reproducibility of 13C and 15N hyperpolarization using a cryogen-free DNP polarizer
Photo (a,b) and diagram (c) of the polarizer used in this work. The polarizer consists of a dissolution module (a) mounted on the magnet (b section, magenta square) and a rack for auxiliary parts. The dissolution module (a) contains an inlet for the dissolution medium (DM), a heater for DM (5), a Swagelok manifold (1–4), a switch valve (6), the sample cup and an outlet. The magnet (b section, magenta square) is equipped with a variable temperature inset (VTI) which is cooled down to 1.4 K by evacuating a bath of liquid helium at the bottom of the VTI. The pressure of helium gas inside the VTI and in the inlet are shown by P1 (8) and P2 monitors respectively. The DNP probe inside the VTI consists of a tunnel for the sample cup, a waveguide to transmit the microwaves, and an NMR coil at the bottom. The sample is inserted into the VTI via an airlock (7) on top. The rack is used to house the pump circulating the Helium of the VTI, an NMR spectrometer, the magnet power supply, temperature controllers and the user interface. Figure c shows a schematic view of the polarizer naming all the main components.
