Moisture in Ammonia
|Solution 1:||SYSTEM: IRGAS EP/Hx+||Spectrometer: MB3000||Cell: Ranger-EN||Software: SPGAS, Spectra Stream|
The highest purity of ammonia is a requisite chemical gas for the production of flat panel displays and for LEDs; the purity issue is one of achieving moisture levels at the ppb level, as in the case of epitaxial reactor applications. However, the problem requiring a solution derives in part from the fact that the FTIR spectra for moisture and ammonia overlap to the degree that the moisture peaks are masked by the ammonia peaks at high concentrations. As a result the moisture peaks cannot be used for quantitative concentration measurements. The IRGAS Solution utilizes the method of subtracting the 100.0000% pure ammonia spectrum from the sample spectrum of ammonia and moisture to obtain only the moisture spectrum for measurement. The 100.0000% ammonia is obtained by using a moisture/ammonia purifier with the highest purity ammonia available. Standard moisture calibrations methods for moisture in N2 are then applied to effect a moisture in ammonia calibration set. Since moisture concentrations in the 1 to 10 ppb range are of the greatest concern, the highest performance hardware and software are required. The IRGAS Solution is the EPI/Hx which combines the MB3000 with the Ranger-EN 9.6-meter gas cell and the SPGAS/SprectraStream software plus other components. This same Solution is applicable to all the other hydrogen-rich chemical species: PH3, SiH4, GeH4, B2H6, etc.