ICP-AES中光谱干扰的计算机模拟——Ⅲ.有效谱线轮廓模型的建立

COMPUTER SIMULATION OF SPECTRAL INTERFERENCES IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROSCOPY——Ⅲ. The Mathematical Model for the Effective Line Profiles

本文首先通过Voigt函数描述ICP-AES的仪器轮廓,经过解卷积从中分出一个Gauss成分和一个Lorentz成分,两种成分的比例由一个参数a_1决定;将Gauss成分与Doppler变宽轮廓进行二次卷积,Lorentz成分与碰撞变宽轮廓进行线性卷积,并将表征谱线有效轮廓的Voigt函数展开为Whiting近似式,从而实现了对谱线轮廓的快速计算。通过与实验扫描光谱进行对比,表明ICP-AES的仪器轮廓基本属于Vloigt轮廓的一种极端情形——Gauss轮廓。

A modified mathematical model was proposed to describe the effective line profiles in ICP-AES. The Voigt function is used to describe the instrumental profile. It is assumed that a Gaussian and a Lorentzian parts can be split from the instrumental profde by dcconvolution. The ratio of Gaussian and Lorentzian components in the instrumental profile is determined by an a-parameter a_1. The Gaussian component of the width of the instrumental profile is quadratically convoluted with the Doppler width, and the Lorentzian component is linearly convoluted, with the width of collisional broadenings. The Voigt function for description of the effective line profiles is approximately computed by Whiting's method. The results show that the model was fairly efficient. It has been proved that the instrumental profile of a medium resolution spectrometer has approximate Gaussian distribution by comparing the simulated line profiles with the experimental ones.