Detection And Analysis Of Food Additives Based On Terahertz Time-domain Technology

Terahertz(THz)wave means the electromagnetic radiation between microwave and infrared,generally refers to the frequency range of electromagnetic wave between 0.1 Terahertz to 10 Terahertz.The vibration frequency of many biological molecules is located at terahertz frequencies,and terahertz radiation has the characteristic such as low energy and don't cause damage to the structure and activity of biological molecules,thus terahertz technology become a new research tool of structure and properties of biological molecules.In this paper,Gaussian09 and terahertz time-domain spectroscopy were applied to simulate and detect the spectrum of vanillin,sodium cyclamate,benzoic acid and sorbic acid.The main content of this paper is as following:The first part introduces the background and development of THz-TDS in detection of food additives.The second part introduces the detection principle of terahertz time-domain technology.The third part introduces the theory of infrared spectrum simulation.Gaussian09 software was applied to simulate the vibrational spectrum of vanillin,sodium cyclamate,benzoic acid and sorbic acid,and the molecular vibration modes within the scope of 0.1-10THz were analyzed.In fourth part,terahertz time-domain spectroscopy(THz-TDS)system was used to measure the spectrum of sodium cyclamate,benzoic acid,vanillin and sorbic acid,and the absorption spectrum and the refractive index within the scope of 0.1-2.5THz were analyzed.Compared with the simulation result,found that vanillin has absorption peaks at 0.61THz,1.15THz,1.54THz,1.83THz,2.12THz,2.43THz in the experimental result and has absorption peak at 2.14THz only in the simulation result;sodium cyclamate has absorption peaks at 1.40THz,2.11THz,2.45THz in the experimental result and has absorption peaks at 1.16THz,2.20THz in the simulation result;benzoic acid has absorption peaks at 0.93THz,1.58THz,1.84THz,1.99THz,2.29THz in the experimental result and has absorption peak at 2.05THz only in the simulation result;sorbic acid has absorption peaks at 1.23THz,1.41THz,1.61THz,1.95THz,2.44THz in the experimental result and has no absorption peak in the simulation result.The difference between experimental result and simulation result was explained.