Su E G, Irwin R L, Liang Z, Michel R G
Department of Chemistry, University of Connecticut, Storrs 06269-3060.
Anal Chem. 1992 Aug 1;64(15):1710-20. doi: 10.1021/ac00039a016.
Instrumentation was constructed to modulate the dye laser wavelength for background correction in laser-excited atomic fluorescence spectrometry (LEAFS). To achieve wavelength modulation a piezoelectric pusher was used to drive the wavelength tuning mirror in a laboratory-constructed grazing incidence dye laser. The laser pulses were synchronized with the piezoelectric pusher movement so that alternate laser pulses measured the atomic fluorescence signal at the analytical atomic spectral line (on-line) and the background signal at a wavelength displaced to one side of the atomic line (off-line). The background-corrected signal was obtained by subtracting the off-line "background" from the on-line "signal plus background". The spectral line width (fwhm) of the dye laser was 0.003 nm, while the wavelength modulation interval was controllable over the range from 0 to 0.2 nm with a spectral resolution limited only by the spectral line width of the laser. This type of background correction could, in principle, be applied to other types of tunable lasers such as pulsed Ti: sapphire lasers. The performance of background correction by wavelength modulation (WM) was demonstrated by measurement of sodium resonance fluorescence in an air-acetylene flame and by thallium nonresonance fluorescence in a graphite furnace. The experimental data indicated that the wavelength modulation corrected, effectively and quantitatively, for flame background, blackbody emission from a graphite furnace, and scatter of laser radiation off aluminum chloride (1 mg/mL as AI) matrix particles in both the furnace and the flame. Analytical results were in good agreement with certified values for the determination of sodium in standard reference materials by the use of modulated LEAFS.
构建了一种仪器，用于在激光激发原子荧光光谱法（LEAFS）中调制染料激光波长以进行背景校正。为实现波长调制，在实验室构建的掠入射染料激光器中使用压电推杆驱动波长调谐镜。激光脉冲与压电推杆的运动同步，以便交替的激光脉冲在分析原子谱线处（在线）测量原子荧光信号，并在原子谱线一侧偏移的波长处（离线）测量背景信号。通过从在线“信号加背景”中减去离线“背景”来获得背景校正信号。染料激光的谱线宽度（半高宽）为0.003 nm，而波长调制间隔在0至0.2 nm范围内可控，光谱分辨率仅受激光谱线宽度限制。原则上，这种类型的背景校正可应用于其他类型的可调谐激光器，如脉冲钛宝石激光器。通过测量空气 - 乙炔火焰中的钠共振荧光和石墨炉中的铊非共振荧光，证明了波长调制（WM）背景校正的性能。实验数据表明，波长调制有效地、定量地校正了火焰背景、石墨炉的黑体发射以及炉内和火焰中激光辐射在氯化铝（1 mg/mL，以Al计）基体颗粒上的散射。使用调制的LEAFS测定标准参考物质中的钠时，分析结果与认证值吻合良好。
