AOTF在光谱分析中的应用研究——3.AOTF在原子发射光谱分析中的应用

本文报道了一台以声光可调滤光器(AOTF)为分光元件的自装ICP原子发射光谱仪.其硬件及软件系统均为自行设计.采用的TeO2晶体为Brimrose TEAF5-0.36-0.52-S.波长校正采用了Ca,Y,Li,Eu,Sr和Ba等六个元素的十四条谱线,经十次拟合后波长值误差小于0.1 nm.不同PMT电压下测定的峰值偏差小于0.04 nm.Ba,Y,Eu,Sc和Sr等五个元素的校正曲线平均相关系数为0.999 1,检出限在0.051～0.97 μg*mL-1范围. 在488 nm处半峰高宽度约为2.1 nm,如不采取增强分辨率的措施,该仪器在原子发射光谱分析中的应用有一定的局限性.

Application of AOTF in Spectral Analysis——3. Application of AOTF in Atomic Emission Spectral Analysis

An atomic emission spectrometer based on acousto-optic tunable filter (AOTF) was self-constructed and was used to evaluate its practical use in atomic emission analysis. The AOTF used was of model TEAF5-0.36-0.52-S (Brimrose, USA) and the frequency of the direct digital RF synthesizer ranges from 100 MHz to 200 MHz. ICP and PMT were used as light source and detector respectively. The software, written in Visual C++ and running on the Windows 98 platform, is of an utility program system having two data banks and multiwindows. The wavelength calibration was performed with 14 emission lines of Ca, Y, Li, Eu, Sr and Ba using a tenth-order polynomial for line fitting method. The absolute error of the peak position was less than 0.1 nm, and the peak deviation was only 0.04 nm as the PMT varied from 337.5 V to 412.5 V. The scanning emission spectra and the calibration curves of Ba, Y, Eu, Sc and Sr are presented. Their average correlation coefficient was 0.9991 and their detection limits were in the range of 0.051 to 0.97 micrograms.mL-1 respectively. The detection limit can be improved under optimized operating conditions. However, the spectral resolution is only 2.1 nm at the wavelength of 488 nm. Evidently, this poor spectral resolution would restrict the application of AOTF in atomic emission spectral analysis, unless an enhancing techniques is integrated in it.