Surface-enhanced IR Absorption Spectroscopy And Applications Based On CH₃NH₃PbBr₃-QDs/SiO₂ Films

The unique optical properties of metallic nanoparticle films enable the enhancement of infrared absorption of ad-molecules,This phenomenon was called surface-enhanced infrared absorption effect.Spectroscopy based on this effect,i.e.,surface-enhanced infrared absorption spectroscopy(SEIRAS)was a powerful investigating tool for surface and interface analysis at molecular level.Halide perovskite material was a very promising high-performance optoelectronic device material.However,in humid environments,perovskite stability was poor so that its application was limited,This paper used SiO2 to encapsulate the perovskite material to form a thin film,making it more stable.The products were characterized by UV-Vis absorption spectroscopy,Fourier transform infrared spectroscopy,X-ray diffraction,fluorescence spectroscopy and high resolution transmission electron microscopy.The stability of the films in wet environment was also investigated.The surface enhancement infrared absorption effect of the film was evaluated using two nitro compounds,followed by the detection of the nitro compound composition in the explosive.The study was as follows:First,the hybrid perovskite CH3NH3PbBr3 quantum dots were prepared and the silica-coated quantum dots were prepared by slow hydrolysis of tetraethyl orthosilicate.Then,the CH3NH3PbBr3-QDs/ SiO2 films was prepared.The prepared hybrid perovskite quantum dots were characterized by Fourier transform infrared spectroscopy,UV-Vis absorption spectroscopy,X-ray diffraction,fluorescence spectroscopy,high-resolution transmission electron microscopy.The experimental results showed that the prepared quantum dots had an average diameter about 8 nm,and had a good photon absorption capacity.The stability of quantum dots and SiO2 composite films was better in hot and humid environment.Second,the CH3NH3PbBr3-QDs/ SiO2 composite films were used to detect the surface enhanced infrared absorption of paclitaxel(TNP)and p-nitrophenol(PNP).According to the formula of increasing the multiplication factor(E = I1m2 / I2m1),when the sample quality of TNP is 10?g,the enhancement ratio can reach 8.When the concentration of TNP is 0.1mg,the enhancement ratio can reach 6.When the sample quality of PNP is 10?g,the enhancement ratio can reach 26;when the concentration of PNP is 0.1mg,the enhancement ratio can reach 14.In the end,the surface enhanced infrared absorption of different concentrations of TNP and PNP was detected by CH3NH3PbBr3-QDs/ SiO2 composite thin films.In this study,the nitro-stretching vibration peak about 1340 cm-1 of nitroaromatic compounds were used as the analysis objects.In the range of 0.5 ~ 5mmol / L,TNP and PNP showed a good linear relationship with the peak height at this peak position,and the corresponding regression curves and equations were obtained.At the same time,the PNP in the explosive extract was detected and the influence of the interfering substance was explored.The experimental results showed that the samples were extracted with toluene as the extraction solvent,and the samples were extracted with ammonium nitrate,sodium silicate and hydroxymethyl cellulose,the effect of PNP on the infrared spectrum is extremely small,and this method can be used to detect PNP in explosives.