Maslar James E, Kimes William A, Sperling Brent A, Kanjolia Ravindra K
1 Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA.
2 EMD Performance Materials, Haverhill, MA, USA.
Appl Spectrosc. 2017 Dec;71(12):2632-2642. doi: 10.1177/0003702817716939. Epub 2017 Jul 14.
A nondispersive infrared (NDIR) gas analyzer was demonstrated for measuring the vapor-phase density of the carbonyl-containing organometallic cobalt precurso μ-η-(Bu-acetylene) dicobalthexacarbonyl (CCTBA). This sensor was based on direct absorption by CCTBA vapor in the C≡O stretching spectral region and utilized a stable, broadband IR filament source, an optical chopper to modulate the source, a bandpass filter for wavelength isolation, and an InSb detector. The optical system was calibrated by selecting a calibration factor to convert CCTBA absorbance to a partial pressure that, when used to calculate CCTBA flow rate and CCTBA mass removed from the ampoule, resulted in an optically determined mass that was nominally equal to a gravimetrically-determined mass. In situ Fourier transform infrared (FT-IR) spectroscopy was performed simultaneously with the NDIR gas analyzer measurements under selected conditions in order to characterize potential spectroscopic interferences. Interference due to CO evolution from CCTBA was found to be small under the flow conditions employed here. A CCTBA minimum detectable molecular density as low as ≈3 × 10cm was calculated (with no signal averaging and for a sampling rate of 200 Hz). While this NDIR gas analyzer was specifically tested for CCTBA, it is suitable for characterizing the vapor delivery of a range of carbonyl-containing precursors.
展示了一种用于测量含羰基有机金属钴前驱体μ-η-(丁基乙炔)二钴六羰基化合物（CCTBA）气相密度的非色散红外（NDIR）气体分析仪。该传感器基于CCTBA蒸汽在C≡O伸缩光谱区域的直接吸收，使用了稳定的宽带红外灯丝源、用于调制光源的光学斩波器、用于波长隔离的带通滤波器和锑化铟探测器。通过选择校准因子将CCTBA吸光度转换为分压来校准光学系统，当用于计算CCTBA流速和从安瓿中去除的CCTBA质量时，得到的光学测定质量名义上等于重量法测定的质量。在选定条件下，与NDIR气体分析仪测量同时进行原位傅里叶变换红外（FT-IR）光谱分析，以表征潜在的光谱干扰。发现在此处采用的流动条件下，CCTBA释放出的CO引起的干扰很小。计算出CCTBA的最低可检测分子密度低至≈3×10cm（无信号平均，采样率为200Hz）。虽然该NDIR气体分析仪是专门针对CCTBA进行测试的，但它适用于表征一系列含羰基前驱体的蒸汽输送情况。
