Research in the de Vries Group involves a powerful combination of Laser Spectroscopy and Mass Spectrometry by employing laser induced desorption of molecules from surfaces, supersonic jet-cooling, multiphoton spectroscopy, and mass spectrometry.
This instrument combines high resolution gas phase laser spectroscopy and mass spectrometry. The instrumental methodology consists of : (1) laser desorption, (2) supersonic jet cooling, (3) post-ionization, and (4) time-of-flight mass spectrometry.
To analyze the compounds of interest, they must first be in the gas phase. Compounds are first placed on a graphite sample bar as a solid. The sample is then desorbed through the use of a pulsed IR laser. The IR light is absorbed by the graphite bar heating up the sample holder. This quick heating provides the energy for the sublimation process to occur on the specific part of the bar that was hit by the laser spot. The analyte is now in the gas phase, but the compound is hot and therefore exists in different vibrational levels. Further analysis of this hot gas would produce hot bands, artifacts that make the results more difficult to analyze. In order to reduce the formation of hot bands, the gas is cooled through a process known as “jet cooling”. Pressurized argon gas is streamed into the vacuum chamber and collides with the hot compound. Through these collisions, the analyte transfers its energy to the argon while simultaneously directing the analyte into the skimmer for further analysis. This results in the internal temperature of the gas reaching as low as 10-20K.
A representation of the molecular beam.
The de Vries lab maintains a variety of laser systems, in addition to having access to the to the UCSB Optical Characterization Facilities.