Wu Z, Tong W G
Department of Chemistry, San Diego State University, California 92182.
Anal Chem. 1993 Jan 15;65(2):112-7. doi: 10.1021/ac00050a004.
Optical phase conjugation by "forward-scattering" degenerate four-wave mixing in an absorbing liquid analyte solution is reported as a sensitive and simple nonlinear laser spectroscopic method. Since only two input laser beams are used in this nonlinear four-wave mixing setup, it offers important advantages including ease of optical alignment, efficient use of input photon density, low laser power requirements, and high wave-mixing efficiency. In addition, since the phase-conjugate signal is a laser beam, optical signal detection is very efficient and the signal-to-noise is excellent. Important characteristics of this novel nonlinear laser technique, including signal dependence on analyte concentration, individual input beam power, and modulation frequencies, are examined. Excellent detection sensitivity, small detection volume, and convenient sample introduction promise many applications for this nonlinear laser spectroscopic method. Preliminary detection limits of 0.7 amol of eosin B and 45 amol of iodine inside a probe volume of 98 pL are reported using a forward-scattering degenerate four-wave mixing setup.
据报道，在吸收性液体分析物溶液中通过“前向散射”简并四波混频实现的光学相位共轭是一种灵敏且简单的非线性激光光谱方法。由于在这种非线性四波混频装置中仅使用两束输入激光束，它具有诸多重要优势，包括易于光学对准、有效利用输入光子密度、低激光功率要求以及高波混频效率。此外，由于相位共轭信号是一束激光束，光信号检测非常高效且信噪比极佳。研究了这种新型非线性激光技术的重要特性，包括信号对分析物浓度、单个输入光束功率和调制频率的依赖性。出色的检测灵敏度、小检测体积和便捷的样品引入为这种非线性激光光谱方法带来了众多应用前景。使用前向散射简并四波混频装置，在98皮升的探测体积内，曙红B的初步检测限为0.7阿托摩尔，碘的初步检测限为45阿托摩尔。
