混合溶液中CARS过程的非共振信号实验研究

相干反斯托克斯拉曼散射是一种非线性四波混频效应，但是通过探测共振信号不易进行物质成分的定量光谱分析。本文利用单频相干反斯托克斯拉曼散射光谱分析法，对不同体积比混合的乙醇溶液在远离双光子共振跃迁及其远离溶质与溶剂的特征拉曼共振态位置进行了光谱探测。通过对实验结果进行分析发现，在共振位置2 876 cm-1的信号强度随混合溶液中的乙醇的体积比增加而增加，呈二次方关系。而在远离共振态位置的非共振信号强度随混合溶液中乙醇的体积比增加而增加，且呈线性关系，进而说明了非共振信号强度随着分子数浓度N呈线性变化关系。因此，通过探测非共振信号强度与分子数浓度关系可以为混合物中特定成分的定量光谱分析提供一种研究途径。

Experimental Study on the Non-Resonant Signal of the CARS Process in Mixture

Coherent anti-Stokes Raman scattering is a nonlinear coherent four-wave mixing effect. But it is hard to quantitatively spectral analyze material components by detecting coherent signal. In the present paper, the resonant and non-resonant signals of mixture of ethanol and water with different volume ratio were experimentally studied with a single-frequency coherent anti-Stokes Raman scattering spectral method. By analyzing the experimental results, we found that the intensity of resonance signals at frequency 2 876 cm-1 is increased with the increase in volume ratio of ethanol and it is quadratic, but the intensity of non-resonant signal linearly increased with the volume ratio of ethanol. So the non-resonance intensity signal is linear with the concentration of the number of molecules N. Therefore, detecting the non-resonance signal will provide a way for the quantitative spectral analysis of the specific ingredients in the mixture.