Know the Performance Parameters of AAS Monochromator
单色仪是一个重要的光学部件Atomic Absorption Spectrometer. It plays the function of isolating the wavelengths of interest from the broad spectrum of wavelengths emanating from the hollow cathode lamp. For a brief description of monochromator component parts and their role browse through the articleDispersion and resolution of light in atomic absorption spectroscopy.
The ideal distribution of monochromator output is triangular shaped. The selected wavelength lies in the centre with nearby wavelengths decreasing linearly on both sides till a cut-off value is reached where it stops decreasing further. The cut-off value is typically about one thousandth of the peak value, or 0.1%.
在本文中，这些参数将更多详细讨论，以便您可以欣赏他们对单色仪性能的贡献。
单色仪Performance Parameters:
单色仪焦距
The focal length of the collimating mirrors has a bearing on their resolving power. Large focal lengths improve resolution of overlapping or closely spaced absorption bands. The exit slit is positioned at the focus of the collimating mirrors so that a sharp image of dispersed light reaches the exit slit.
Slit Width
提供狭缝，用于允许宽波长光进入单色器中并允许出口隔离波长光。狭缝宽度以mm表示。窄狭缝提供更好的分辨率，但限制了灵敏度，因为这些敏感性防止分散光的分数到达检测器。在标准设计中，入口和出口狭缝都具有相同的宽度，但在研究级仪器中，提供了可由用户控制的可变狭缝宽度。
光谱带宽
The monochromator output is a narrow band of isolated wavelengths. The bandwidth is inversely related to the resolving power of the monochromator. It is defined as the width of the triangle at the points where the light reaches half the maximum value and is referred to as full width at half maximum (FWHM).
Dispersion
分散是单色器分离不同波长的能力。
Angular dispersion refers to change in angle of reflection r with change of wavelength
Angular Dispersion= dr/dλ
线性色散d表示波长变化的焦平面处的距离变化
D = dy/dλ
其中Y表示沿焦平面的距离，λ是波长。
When focal length of collimating mirror is F then
dy = Fdr which on substitution in the linear dispersion equation gives
D = Fdr/dλ
Commonly reciprocal linear dispersion \(D^-^1\) is used to express the dispersion of grating monochromators
\(D^-^1\) = dλ/Fdr
Stray Light
杂散光是从单色器中出现的辐射，而不通过分散元件。由于单色器内的灰尘颗粒以及各种光学表面上存在散热颗粒，散射辐射产生。
请分享你的评论和offer suggestions.
When you state that the function of the monochromator is to isolate “the wavelengths of interest from the broad spectrum of wavelengths emanating from the hollow cathode lamp”, it implies that the HCL is a broadband source, which is not the case. It would perhaps be better stated that the function is to isolate a single emission line from the emission spectrum of the metal(s) in the cathode.