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Chemistry

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Analytical Chemistry

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Atomic Spectroscopy

Measuring Elements by Atomic Fluorescence

Description

Atomic fluorescence spectroscopy measures elements by detecting the light atoms give off after they are excited by electromagnetic radiation. The atoms are first placed in a flame, furnace, or plasma. They absorb energy, become excited, and then release that energy as they return to their original state. The emitted light is...

Transcript

在原子荧光光谱法(AFS)中,将原子化的样品暴露于电磁辐射下以引发电子跃迁,并检测所发射的荧光辐射。

AFS 仪器具有高强度光源、原子化器、波长选择器和检测器。可能的激发光源包括脉冲空心阴极灯、无极放电灯、氙弧灯或汞弧灯以及激光器。

与原子吸收光谱法(AAS)类似,待测元素被原子化后,由光源激发。受激原子通过荧光释放能量,其波长对应于特定的原子种类,从而回到较低的能量状态。

由于原子在其最佳吸收波长处发生荧光,光源光束与检测器(通常为光电倍增管)呈直角排列。

荧光强度与目标元素的浓度成正比。它还与辐照强度成正比,因此需要高强度光源并尽量减少干扰辐射。

尽管如此,原子荧光光谱法在识别易形成挥发性氢化物的元素和汞方面尤为...