Design of a pulsed valve for high-pressure NH3 injection into supersonic beam/mass spectrometry

A novel design of a pulsed valve for high-pressure injection of NH3 for supersonic jet expansions is presented. This valve can operate up to 200-atm reservoir pressure at 180 °C with a pulse width down to 100 μs. This valve has been designed so that the solenoid core is not in contact with the carrier fluid so that it can be used with highly polar corrosive liquids or supercritical fluids. The ability to use supercritical NH3 as a means of injecting small thermally labile biological molecules into supersonic jet expansions for analysis by resonant two-photon ionization in a time-of-flight mass spectrometer is demonstrated.