High Temperature Mass Spectrometry

The HTMS is a unique facility for studying high temperature inorganic vapors. These vapor may be produced from either direct vaporization of solids or gas/solid reactions which lead to gaseous products. There are two major instruments for vaporization studies, shown in the figures.

Figure 1 illustrates our Knudsen Cell mass spectrometer. This is Nuclide/Spectrumedix 12-90-HT, which has been modified for our applications. The instrument is based on a Knudsen Cell, which allows condensed phase/gas equilibrium and contains a small orifice for sampling the vapor. The vapor is then analyzed with a conventional magnetic sector mass spectrometric technique. We have three Knudsen Cell configurations--a standard single cell flange for conventional vaporization measurements, a double cell flange which allows precise thermodynamic activity measurements, and a gas leak cell for studying low pressure gas/solid reactions. Current studies include thermodynamics of Ti-Al alloys and BN/H2O interactions.

Figure 2 illustrates our molecular beam sampling mass spectrometer. This allows direct sampling of a vapor produced in an atmospheric process, such as a combustion process, chemical-vapor-deposition process, or high temperature corrosion process. The sampled vapor undergoes a free jet expansion into the first vacuum chamber. This leads to beam cooling and near collisionless flow, thereby preserving chemical and dynamic integrity of the sampled vapor. The beam then goes through a series of differentially pumped vacuum chambers till it reaches a quadrupole mass analyzer in ultra-high vacuum. Current studies include SiO2/H2O interactions.

Contact: Dr. Nate Jacobson or Dr. Evan Copland