Effects Of Hydrostatic Pressure On The Three Dimensional Fluorescence Spectra Of A Series Of PAHs

Investigations of the specific properties of PAHs(polycyclic aromatic hydrocarbons)under high pressure are of great importance to reveal how the organic substances transmitted into the earth and to investigate the origin of life,in the meantime,the high-pressure research of PAHs is fundamental to promote the high-pressure synthesis technology.Otherwise,the three dimensional fluorescence spectrum technology(3DFS)can reflect the fluorescence intensity with the both variation of excitation wavelength and emission wavelength,which means 3DFS can provide much more information than traditional two dimensional fluorescence spectra,and the 3DFS can reflect tiny discrimination of spectra,so in this article the 3DFS will be applied to investigate the high-pressure fluorescence properties of PAHs.The effects of hydrostatic pressure on the 3DFS of a series of pure PAHs(naphthalene,fluorene,phenanthrene,acenaphthene,fluoranthene,and anthracene)with three different concentrations(10-6 mol L-1,10-5 mol L-1,and 10-4 mol L-1)were investigated in a pressure range from 0.1 MPa to 60 MPa at room temperature.According to the 3DFS,2(naphthalene)to 12(anthracene)fluorescence peaks were observed and the variation of 3DFS under high pressure were revealed by analyzing the fluorescence peaks positions and intensities with the increased hydrostatic pressure.It is found that fluorescence peak shifts were not detected in the compression,however,both the enhancement of intensity and reduction of intensity were observed.Otherwise,the pressure effects were magnified when the concentration was increased.The effects of hydrostatic pressure on the 3DFS of binary mixed solvents(the mixed solvents were prepared by the 6 PAHs,naphthalene,fluorene,phenanthrene,acenaphthene,fluoranthene,and anthracene,and the concentration of each component in binary mixed solvents was 10-6 mol L-1)were also investigated in a pressure range from 0.1 MPa to 60 MPa at room temperature.The consequences revealed that the fluorescence peak of binary PAHs mixed solvents were same with that of pure PAHs under ambient pressure,and the fluorescence peaks shifts were not detected when the hydrostatic pressure was elevated.However,the variation of fluorescence intensity of fluorescence peaks were universally observed,and the response of fluorescence intensity to the increase of hydrostatic pressure was different to that of pure PAHs solution.