Molecular Beam Machine

Molecular Beam Machine Diagram

The Beam Machine combines high resolution gas phase laser spectroscopy and mass spectrometry. The molecule of interest in placed on the sample holder, where a laser is used to desorb the molecules into the gas phase. Laser desorption is a method that is used extensively in the de Vries lab to introduce nonvolatile and/or thermally labile samples into the gas phase.

The molecules are then entrained in a Molecular Beam,which is a supersonic jet expansion formed when a high pressure gas is expanded through a small nozzle orifice into a vacuum. Translational temperatures of less than 1 K are easily attainable in these expansions, and the molecules entrained in this gas will have energies characteristic of these low translational temperatures. This cooling will in turn reduce the number of populated rotational and vibrational modes, leading to very high resolution spectroscopy.

These cold, gas phase molecules are then photo-ionized by intersecting the Molecular Beam with tunable UV lasers, specifically using a scheme known as resonant-2-color-ionization (R2PI). These ions travel through a reTOF mass spectrometer before being detected by a micro-channel platedetector.