Nozzle jet expansion

The ability to cool (and eventually liquefy) gases by adiabatic expansion underlies industrial gas liquefaction processes. Adiabatic cooling of gaseous nozzle-jet expansions is also an important technique in modem molecular beam and mass spectrometric research. Thermodynamicist John Fenn, winner of the 2002 Nobel Prize in Chemistry, pioneered many of the techniques of adiabatic nozzle-beam cooling. 

From a historical perspective, the first unambiguous observation of dipole states came from the group of Kit Bowen (Johns Hopkins) in 1990, who studied the important water dimer dipole anion. The Bowen group has also studied ground state dipole-bound anions produced by electron attachment under high-pressure nozzle-jet expansion condition. They have also used photodetachment photoelectron spectroscopy to determine electron affinities for a number of the molecules shown in Figure 4. 

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