两种激发波长下蔬菜水果的拉曼光谱对比研究

Raman Spectra of Vegetables and Fruits at Two Excitation Wavelengths

本文通过改变不同的激光光源波长,测试分析了一系列蔬菜水果表面的拉曼谱。比较514.5nm和1064nm波长下的拉曼谱,发现514.5nm激发下许多蔬菜水果的拉曼谱均出现胡萝卜素的共振拉曼光谱,同时有很强的光荧光。更换成1064nm的近红外激光波长后,基本消除了光荧光和共振效应的影响,可用来测量蔬菜水果的有效成分,而514.5nm激发下只出现胡萝卜素的光谱,为区分蔬菜水果表面的外来物质,如农药,提供了很大的方便。

The Raman spectra of vegetables and fruits were studied by micro-Raman spectroscopy at 514.5nm excitation, and near-infrared Fourier transform Raman (FT-Raman) at 1064nm. It is shown that at 514.5nm excitation, most of the spectra recorded on the surface of vegetables and fruits are from that of carotene, and the fluorescence is very strong in some cases. While at 1064nm excitation wavelength,the spectra show that different samples demonstrate different characteristic Raman spectra without fluorescence. Thus, one can analyses the effective compositions in these vegetables and fruits by FT-Raman, while under 514.5nm excitation, the only spectra from carotene provide a great convenience for detecting other components left on the surface of vegetables and fruits, such as pesticide.