FLOW AFTERGLOW DESIGN

THIS PROPOSAL IS FOR THE CONSTRUCTION OF AN ADVANCED FLOWING AFTERGLOW APPARATUS WITH SUFFICIENT PUMPING SPEED TO HANDLE BOTH NEUTRAL-NEUTRAL AND ION-NEUTRAL REACTION RATE COEFFICIENT MEASUREMENTS. THREE NEUTRAL-NEUTRAL FLOW TUBES OF DIFFERENT DIAMETERS ARE PROVIDED TO BE ABLE TO ASSESS WALL EFFECTS. ONE GENERAL PURPOSE ION-MOLECULE FLOW TUBE IS PROVIDED. THE ION DETECTOR IS A TRIPLE QUADRUPOLE TANDEM MASS SPECTROMETER WHICH ALLOWS ABSOLUTE DETERMINATION OF THE CHEMICAL NATURE OF THE IONS OBSERVED. IN THE NEUTRAL-NEUTRAL EXPERIMENTS THE SAMPLE IS PRESENTED TO THE MS/MS IONIZER AS A MODULATED MOLECULAR BEAM TO DISTINGUISH IONS FORMED FROM MOLECULES IN THE BEAM FROM THOSE IN THE RESIDUAL GAS IN THE VACUUM CHAMBER. OPTICAL WINDOWS ALONG THE LENGTHS OF THE FLOW TUBES PERMIT DETECTION OF REACTANTS AND PRODUCTS BY SPECTROSCOPIC MEANS INCLUDING LASER ABW SORPTION AND FLUORESCENCE. THE INSTRUMENT IS HARDENED TO ALLOW ITS USE WITH CORROSIVE GASES. A GAS HANDLING SYSTEM IS PROVIDED TO ALLOW PRECISE MEASUREMENTS OF GAS FLOWS OVER THE WIDE RANGE REQUIRED FOR BOTH ION-NEUTRAL AND NEUTRAL-NEUTRAL REACTION STUDIES. AN IBM-PC BASED DATA SYSTEM IS PROVIDED.