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要使背景得到完全的校正,必须使原子吸收测量和背景测量在同一波长进行,必须使这两个测量具有相同的测量时间和空间。由于测量时间差引起的误差可以表述为: ΔA_B=M_(αx)[dA_B(t)/dt]Δt (1) 其中A_B(t)是原子化周期背景吸收信号对时间的函Δ数,t是采样时间差。由于光束不重合也会造成测量误差,以氘灯背景校正器为例:如果σ和θ′分别为HCL和D_2灯的像斑面积,K_B′和K_B分別为σ和σ′面积上的背景吸收系数,K_B=K_B′(1+α),背景校正的误差可以表达为: 由于背景吸收,光源辐射衰减,背景校正系统的光子噪声可表达为等式(3)可以看出背景校正的误差随背景吸收系数K_B指数上升。在光子噪声为背景校正系统限定影响时,背景校正能力可以写成为等式(4)表明当K_B=0.86A时,背景校正能力有一个极大值F_(max)=0.245I_0~(1/2)。这些讨论与我们的实验结果能很好地吻合。
For a complete correction of the background, the atomic absorption and background measurements must be made at the same wavelength, and the two measurements must be made with the same measurement time and space. The error due to the measurement time difference can be expressed as: ΔA_B = M_ (αx) [dA_B (t) / dt] Δt where A_B (t) is the Δ number of the periodical background absorption signal versus time, t is the number of samples Time difference. As the beam does not overlap will result in measurement error, the deuterium lamp background correction as an example: If σ and θ ’, respectively HCL and D_2 lamp spot area, K_B’ and K_B, respectively σ and σ ’area background absorption Coefficient, K_B = K_B ’(1 + α), the error of the background correction can be expressed as follows: due to the background absorption, the radiation attenuation of the light source, the photon noise of the background correction system can be expressed as equation (3) Background absorption coefficient K_B index rose. The background correction capability can be written as equation (4) when photon noise is the limiting influence of the background correction system. When K_B = 0.86A, the background correction capability has a maximum value of Fmax = 0.245I_0 ~ ). These discussions are in good agreement with our experimental results.