Wu Z Q, Tong W G
Department of Chemistry, San Diego State University, California 92182.
Anal Chem. 1991 Sep 15;63(18):1943-7. doi: 10.1021/ac00018a009.
Optical phase conjugation by degenerate four-wave mixing (D4WM) in an absorbing metal-ion solution using a low-power argon-ion laser as the excitation source is demonstrated. This nonlinear laser technique can be used as a sensitive analytical spectroscopic method for trace-concentration measurement of metal ions in a small-volume continuously flowing analyte cell. Several important characteristics are discussed, including the effects of solvent properties, excitation wave-length, laser intensity, and analyte absorptivity on signal intensity. Detection of 0.26 ng (4.4 pmol) of cobalt inside the laser probe volume of 0.14 microL is reported using an excitation wavelength that is 136 nm away from the maximum absorption wavelength of the analyte solution. The minimum absorbance measured in our D4WM experiment is 2.0 X 10(-5) without complex formation for cobalt. The D4WM detection sensitivity, in terms of the concentration-absorptivity product, is 4.05 X 10(-4) cm-1 for cobalt(II) in ethanol. Our preliminary detection sensitivity compares favorably with other laser-based spectrometric methods. This nonlinear laser technique is applicable to both fluorescing and nonfluorescing analytes.
本文展示了在吸收性金属离子溶液中，以低功率氩离子激光作为激发源，通过简并四波混频（D4WM）实现光学相位共轭。这种非线性激光技术可作为一种灵敏的分析光谱方法，用于在小体积连续流动分析物池中痕量浓度金属离子的测量。文中讨论了几个重要特性，包括溶剂性质、激发波长、激光强度和分析物吸收率对信号强度的影响。使用一个与分析物溶液最大吸收波长相差136 nm的激发波长，在0.14微升的激光探测体积内检测到了0.26纳克（4.4皮摩尔）的钴。在我们的D4WM实验中，未形成络合物时钴的最小吸光度为2.0×10⁻⁵。就浓度 - 吸收率乘积而言，乙醇中钴（II）的D4WM检测灵敏度为4.05×10⁻⁴ cm⁻¹。我们初步的检测灵敏度与其他基于激光的光谱方法相比具有优势。这种非线性激光技术适用于荧光和非荧光分析物。
