饱和激发情况下油荧光非线性特征初步分析

Analysis of nonlinear characteristics of oil fluorescence with saturated excitation

利用激光诱导荧光(LIF)技术,从荧光强度和光谱偏移两个角度研究饱和激发状态下油荧光的非线性变化特征。利用能量变化的激光束诱导油样本荧光,获得荧光强度变化数据,通过非线性曲线拟合来标定荧光特征峰位430 nm处的强度变化参数,获得该波长荧光强度的线性变化范围和非线性趋势,并利用探测波长处荧光强度构造出随诱导光强变化的三维油荧光光谱,实现基于激发光能量参量的油样本光谱区分。实验中,针对普通荧光光谱法无法区分的油样本,结合饱和激发状态下油荧光非线性变化和基于激发光能量参量的油样本光谱特征,实现了样本的有效区分。

The oil fluorescence was measured by laser induced fluorescence （LIF） along with enhanced light excitation. The saturation effects in oil fluorescence spectroscopy were studied on two aspects, namely, the fluorescence intensity and spectral offset. In the experiment, it was shown that the intensity of fluorescence becomes to worse when the intensity of excitation pulse raises. The characteristics of fluorescence inten- sity at 430 nm in the linear and nonlinear ranges were derived through polynomial nonlinear curve fitting. Furthermore, the three-dimensional oil fluorescence spectra based on the excitation light energy were re- constructed according to the nonlinear fitting data derived from the fluorescence intensity in the detection wavelengths. The result demonstrated that the offset of oil fluorescence spectral peak and the nonlinear characteristics of the spectrum intensity with saturated excitation can be used to identify the oil samples which can not be distinguished by the general fluorescence spectroscopy.