Detection And Analysis Of Polycyclic Aromatic Hydrocarbons Based On Infrared Spectroscopy Technology

Polycyclic aromatic hydrocarbons(PAHs)refer to compounds in which two or more benzene rings are connected.They have carcinogenicity,teratogenicity and other adverse effects,which are extremely harmful to humans and the environment.Therefore,the detection of PAHs has attracted much attention.At present,the detection technology of polycyclic aromatic hydrocarbons is diverse,and their applicability is different,but there are different problems in the use process,such as detection cycle,sensitivity,and high cost.Since the 1940s,the beginning of the infrared spectroscopy has been the rapid development of infrared spectrum analysis method is one of the most effective method for compound identification,and has simple operation,high sensitivity,low cost advantages,but currently using infrared spectroscopy detection is less for polycyclic aromatic hydrocarbons in report.Therefore,in this paper,four pahs of pyrene,anthracene,phenanthrene and naphthalene were detected by infrared spectroscopy,and the formation mechanism of the infrared spectrum was explained in microscopic theory by molecular simulation and chemical calculation,and the detection of pahs was studied from the perspective of absorption spectrum.The main contents of this paper include:The first part mainly introduces the background of the topic,the research progress of the detection methods of polycyclic aromatic hydrocarbons and the development and research status of infrared spectroscopy.The second part mainly introduces the basic knowledge of infrared spectrum and the detection principle of infrared spectrum system.And the π delocalization effect and sample preparation process are briefly introduced.The third part mainly introduces the principle of infrared spectrum simulation,and through the use of Gaussian09 software,density functional theory is used to select the B3LYP method of 6-31g group of the molecular model of pyrene,anthracene,phenanthrene,naphthalene structure optimization and simulation calculation,the corresponding simulated absorption spectrum.Then use infrared spectroscopy system to measure the spectrum of pyrene,anthracene,phenanthrene and naphthalene in the 4000-400cm-1 band to obtain their corresponding infrared spectra.The fourth part compares and analyzes the simulation calculation results of pyrene,anthracene,phenanthrene and naphthalene molecules with the experimental measurement results,and compares the simulation calculation results with the experimental measurement results.Five absorption peaks with the strongest peaks were selected for each type of pahs,and the two parts were in good agreement with each other at the main absorption peaks,the vibration mode at the corresponding peak is analyzed and discussed.Combined with the theory of π delocalization effect,specific discussions will be conducted in the double bond region(2000-1200cm-1)and fingerprint region(1200-400cm-1),the reasons for the displacement of the absorption peaks of different pahs are analyzed.So,the formation mechanism of infrared absorption spectrum is explained from the microscopic perspective.