Chapter 5. Solid-State NMR Accessories
79
VNMR 6.1C User Guide: Solid-State NMR
01-999162-00 C0402
Doty Solids VT System
The Varian solids VT accessory can also be added to the Doty CP/MAS probe for VT
operation. When this accessory is added, connection of the gas supplies to the probe is
altered in the following ways:
• Body cooling gas is also needed whenever the probe is not at ambient temperature.
Connect the VT gas supply to the probes is made as described in the Doty manual.
• The VT controller is connected to the boost supply and the boost supply is connected
to the probe.
• The liquids upper barrel is pushed down so it touches the top of the probe. The upper
barrel then acts as an exhaust stack.
VT operation requires Vespel end caps. Vespel is less susceptible to thermal deformation at
high temperatures and has a lower coefficient of expansion, so is less likely to slip out at
low temperatures.
Changes in temperature should always be kept small because rapid changes can cause rotor
crashing.