利用表面增强拉曼光谱对光照条件下改性罗丹明-6G失效机理的研究

Studying on the mechanism of modified Rhodamine-6G by surface-enhanceed Raman spectroscopy(SERS)under light conditions

改性罗丹明-6G分子结构复杂,保存不当易分解,为了降低拉曼光谱的荧光背底,提高拉曼光谱信号稳定性,本文对激光波长、增强剂比例、稳定时间、光谱采集等参数的影响进行了优化分析,确定了最优的测试条件激光波长(785 nm)、增强剂比例(V样品∶V增强剂=2∶1)、增强剂和样品混合后放置时间(0.5 h)、采谱条件(采谱时间10 s,积分次数3次)。在该条件下测试了(100~250 mg/L)浓度标准溶液,平行试样三个,以F2峰(2062.5 cm^(-1))峰面积为响应值,建立响应值-浓度曲线,得到了浓度线性方程。此方法线性相关系数为0.968,标准偏差3.85%,检出限为25 mg/L,说明该方法可用于改性罗丹明-6G染料浓度的测定。对光照分解的染料定期取样测试其浓度和特征峰变化情况,结果表明随着光照时间的增加,染料浓度迅速下降,同时H F1∶F2峰高比下降,其中F1峰(935.2 cm^(-1))与取代基中C-F键相关振动峰,F2峰为氧杂蒽键的振动峰,说明罗丹明-6G染料日照分解过程中,主链和支链均发生断裂,其中C-F键更易断裂。

The molecular structure of modified Rhodamine-6G is complex,and it is easy to decompose.In order to reduce the fluorescence back-bottom of Raman spectrum and improve the stability of signal,the influence of laser wavelength,intensifier proportion,stabilization time,spectral acquisition and other parameters were optimized and analyzed in this paper,and the optimal test conditions were determined:laser wavelength(785 nm),intensifier proportion(V sample∶V intensifier=2∶1),stabilization time of enhancer and sample after mixing(0.5 h),spectrum conditions(collection spectrum time 10s,integration times3).Under these conditions,the concentration standard solution(100-250 mg/L)was tested with three parallel samples.The response value and concentration curve were established with the F1 peak area as the response value,and the concentration linear equation was obtained.The linear correlation coefficient of this method was 0.968,the standard deviation was 3.85%,and the detection limit was 25 mg/L,which indicated that this method could be used for the determination of rhodamine-6G concentration.Under light dyes,its concentration and characteristic peak change was determined,the results show that with the increase of time,the dye concentration drops rapidly,as the same time H F1∶F2 peak height ratio decreased,F1 relater to C-F bond,and F2 relater to xanthene bond,during the decomposition process,xanthene bond main chain and C-F bond side chain rupture and the C-F bond is more likely to break.