Temperature programmed desorption-mass spectrometer with supersonic molecular beam inlet system

A novel atmospheric temperature programmed desorption-mass spectrometer (TPD-MS) device based on supersonic molecular beams (SMB) is demonstrated. The coupling between SMB and TPD-MS enables one to obtain highly sensitive TPD measurements with very fast time response (less than 1 s), that makes it possible to distinguish between desorptions from energetically neighboring sites. Quantitative adsorption measurements of adsorbing gas and vapors could be easily done. High detection sensitivity of 4 ng/s for ${\mathrm{H}}_{\mathrm{2}}{\mathrm{O}}^{\mathrm{16}}$ and 100 pg/s for ${\mathrm{H}}_{\mathrm{2}}{\mathrm{O}}^{\mathrm{18}}$ is achieved. The high sensitivity TPD measurements are demonstrated by the ability to monitor simultaneous physical adsorption of nitrogen, oxygen, and water on various sites on carbon fibers at room temperature.