Presentation on theme: "Carrie A. Kauffman, Kyle N. Crabtree, Benjamin J. McCall"— Presentation transcript:
1A Continuous Supersonic Expansion Discharge Nozzle For Rotationally Cold Ions Carrie A. Kauffman, Kyle N. Crabtree, Benjamin J. McCallDepartment of Chemistry, University of IllinoisJune 23rd, 2009
2Motivation Molecular ions Organic Reaction Intermediates Combustion Atmospheric ChemistryInterstellar Chemistry+Simulation of N2+ of the A 2∏u – X 2∑g+ (4-0)Due to the low temperatures and pressures that occur in the interstellar medium, ions dominate the chemistry due to their low reaction barriers. In order to probe these species, laboratory spectra are needed. In addition, spectra of these molecular ions would aid in the understanding of organic reaction intermediates, combustion processes, and atmospheric chemistry.
3Sensitive Cooled Resolved Ion BEam Spectroscopy Supersonic Source For more on the progress of SCRIBES, stay for the next two talks.
4Supersonic Expansion Barrel Shock Mach Disk Low Pressure Region High Pressure GasSmall OrificeAdiabatic Process, dq = 0dU = dq –dwdU = -PVTvib >> Trot > Ttrans , where Trot ~ K
5Design Considerations Maximize ion densityModularLeak tightRobustCompatible with SCRIBES
8Slit Design Advantages Disadvantages Materials Chosen Integration with SCRIBESClusteringPulsedBroks, B.; Brok, W.; Remy, J; van der Mullen, J.; Benidar, A.; Biennier, L. & Salama, F.; Modeling the Influence of Anode-Cathode Spacing in a Pulsed Discharge Nozzle. Spectrochim Acta B, 2005, 60,
9Nozzle Design Advantages Disadvantages Compatibility with SCRIBES PulsedModularMaterialsMcCarthy, M. C., Chen, W.; Travers, M. J. & Thaddeus, P. Microwave Spectra of 11 Polyyne Carbon Chains. Astrophys. J. Suppl., 2000, 129,
10Design 1-3 Atmosphere of backing pressure Orifice Size: 250 to 1000 micron with varying geometryTypical Chamber Pressure 100 mTorr
11Source Nitrogen Gas Running Voltage: -200 to -500 V Running Current: 30 mAOperation Time: 100+ Hours
12Characterization of the source Ion CurrentOptimization of Cooling Capabilities