Real-time measurement of Cp2Mg vapor concentration using the non-dispersive infrared spectroscopy

Abstract

We demonstrated real-time measurement of bis-cyclopentadienyl magnesium (Cp2Mg) vapor concentration by using a non-dispersive infrared (NDIR) spectroscopy. The Cp2Mg concentration was determined by the calibration curve generated through determining the correlation between the Cp2Mg vapor pressure and infrared absorbance at 12.8µm wavelength, which corresponds to the C–H bending oscillation of the molecule. We measured Cp2Mg vapor concentration in real time generated by a bubbling method where the carrier flow rate was varied in the range of 100–1000sccm under fixed total pressure and bottle temperature (700Torr and 30°C). The overall behavior of measured concentration was almost constant throughout the bubbling time; however a slight concentration decrease of 1.6ppm was captured due to the reduction of sublimation efficiency. In addition, the measured concentration was as low as 66.6–68.8% of the saturation concentration calculated from saturation vapor pressure of Cp2Mg. The validity of the measured concentration was evaluated by the comparison between the measured bottle weight losses after continuous bubblings and the mass consumptions calculated from the measured concentrations. Good agreements within 5% deviations were obtained, and it was confirmed that proper concentration was provided by the NDIR measurement.