1. School of Science, Jiangnan University, Wuxi 214122, China
2. School of Internet of Things Engineering, Jiangnan University, Wuxi 214122, China
3. Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, Wuxi 214122, China
4. Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Chengdu 610064, China
Abstract：For sunset yellow and allura red, the fluorescence spectra have been measured with British Edinburgh FLS920 Steady and Time-Resolved Fluorescence Spectrometer. Two geometries which involve the ground state and the excited state of sunset yellow and allura red are constructed by utilizing Gaussian 09W software. Based on the density functional theory and time-dependent density functional theory, the optimization and calculation about the ground state as well as the excited one are completed. The MPWK function and 6-31g (d) basis sets are applied during the optimization process. Compared with the function and basis sets in the former job, the B3LYP functional and 6-311g (d, p) basis sets are employed when the calculation is carried out. With the consideration of the influence of the solvent effects on the calculation results, thereby, it is necessary to add the polarized continuum model. In the end, the calculated fluorescence spectra are compared with the experimental measurement of spectra, respectively, the results about sunset yellow show that the calculated fluorescence peak at 435 nm which has a relative error of 3.57%, compared with the 420 nm by experiment. For allura red, the calculated fluorescence peak at 443 nm, which means a relative error of 2.55% exists, compared with the 432 nm by experiment. That is to say, for the fluorescence peak of sunset yellow and allura red, their relative errors are in the reasonable range. In a word, the calculation results show that the calculated fluorescence peaks are advisable. When studying the fluorescence properties of two molecules, we find the fluorescence peaks are related to intramolecular charge transfer.
Key words：Sunset yellow; Allura red; Fluorescence spectra; Density functional theory
