Nonlinear Optical Properties And Raman Spectroscopy Of Three New Organometallic Complexes

Organometallic Complexes are promising nonlinear optical materials. Their molecule structures have strong π electron conjugated systems and electron transition between organic ligands and center metal atoms, which result an enhancement of their nonlinear polarizabilities. To probe structural characters of organometallic complexes and to investigate their optical properties are significant, which can direct us to synthesize more valuable organometallic complexes for practical applications in nonlinear optics. The principal work in this paper is to investigate the third-order nonlinear optical properties of three new organometallic complexes with Z-scan technique, and study the molecule structural vibration of these complexes .in order to further understand their nonlinear optical characters There are six chapters in this paper, which can be divided into three sections:In the first section, i.e. chapter one, the current status of the development and practical applications of nonlinear optics are introduced briefly The third-order nonlinear optical effect is introduced particularly. In addition, the theory and the method of Z-scan technique are described for the measurement of nonlinear optical coefficients The basic concept of the Raman spetroscopy and Surface Enhanced Raman Scatterring spectroscopy, the development and application of Surface Enhanced Raman Scatterring spectroscopy and principal knowledge of Raman spectrometer are also presented in the paper.In the second section, i.e. chapter two, three and four, firstly, the thermal induced third order nonlinear optical characters of three organometallic complexes (NiL2, CuL2, PdL2) are studied by the Z-scan technique, thermaloptical coefficients of the three compounds excited under different laser wavelengths are calculated The results showthat the thermaloptical coefficients are dependent on excitation wavelengths, the absorptions under these wavelengths and molecular structures of these compounds. Secondly, the third order nonlinear optical properties of these compounds are studied under the excitation of ps pulsed laser with the wavelength of 1064nm using Z-scan technique, nonlinear refractive indices and nonlinear absorption coefficients are calculated according to the Z-scan experiment curves of the compounds. All the three compounds have self defocusing characters and two photon absorptions. Lastly, nonlinear refraction and absorption properties of these compounds are studied by Z-scan technique under the excitation of ps pulsed laser with the wavelength of 532nm The self defocusing and reverse saturation absorption are found in these compounds. Excited state absorption cross sections are obtained through Z-scan curve fitting. Moreover, the relation between the third order nonlinear optical characters of the compounds and their molecular structures is analyzed by connecting the experimental result with molecular structures.In the third section, i.e. chapter five, the normal Raman spectra of NiL2, CuL2, PdL2 powder are studied under the excitation of laser with the wavelength of 632.8nm And aqueous silver colloid is prepared by pulsed laser ablation, from which the surface enhanced Raman spectra of the three compounds are obtained. After preliminary assignment, the identical and different features of vibration of the compounds due to the different central metal atoms are analyzed .In addition, discussions and conclusions are made in the sixth chapter.