| An investigation of nanowires and nanowires array-materials are more and more much attach importance in the area of applied material science and technology. The study of surface enhanced Raman scattering (SERS) effect on the substrate of metal nanowires and nanowires arrays exhibit more interesting variations. Because its. SERS enhanced mechanisms are very abundant, which include normal SERS, tip enhanced Raman scattering (TERS) and hot spots enhanced. It is very significative for enriching SERS mechanisms, out-spreading the application range of SERS and affording the method of study of material. In this paper, the titanium, aluminum and nickel nanowires arrays were prepared on the AAO templates by magnetic sputtering (MS); they were applied in the area of SERS as enhanced substrates, for the first time. The SERS enhancement-mechanisms were studied roundly on the metal nanowires arrays by integrate of experimentation with theoretics.In the dissertation, there are several segments which list as follows:The highly ordered anodic aluminum oxide (AAO) template was fabricated using aluminum anodizing in electrolytes with two-step method. Its performances were researched by some methods, which include AFM, SEM, XRD, visible-UV absorption spectrum, fluorescence spectrum and Raman spectrum. And its principle was discussed, which include three processes. We investigated the relation of AAO template apertures with anodic voltage, and then the function of it had been deduced.The nanowires and nanowires array-materials of silver and nickel were fabricated on AAO template by LMBE. Their forms were investigated by the means of SEM, AFM and TEM. The diameter which about 100nm was very homogeneous, and the length which about 2200nm was very uniformity. So the ratio of length with diameter of the nanowires was about 22. The exterior of the nanowires arrays was very smooth. Moreover, the end of the nanowires which fabricated on AAO template by LMBE was acuminate. So the nanowires arrays of silver and nickel were the tip arrays. The highly ordered nanowires arrays of gold, titanium and aluminum were fabricated on AAO templates by MS. The diameter was about 100nm which consistent with the templates'. And the ends of the nanowires which collocate in hexagon format were tips.The silver nano-film was fabricated on the silicon substrate by the method of vacuum vapor plating. The film was made up with the silver agglomerated particles which the diameter was about 500nm. And the silver agglomerated particles were conglobated with the nanoparticles which the diameter from 70 to 100nm. In this paper, we ablated silver plates in redistilled deionized water using pulsed laser and obtained 'chemically pure' silver nanoparticles. Its diameter, which was good separate and uniform, was about 30nm.On the glasses covered with silver and nickel nanowires respectively, high quality surface enhanced Raman scattering (SERS) spectra of sudanâ…¡(C18H16N20) were obtained. And the comparison of SERS on the silver and nickel nanoparticle indicated that there two enhanced mechanisms which include SERS and TERS on the substrates of the glasses covered with silver and nickel nanowires respectively.On the silver nanowires arrays, high quality SERS spectrum of probe molecules rhodamine 6G (Rh6G) was obtained. Comparison of SERS spectra on the substrates of silver nanowires array with silver film and colloids indicates that enhanced mechanism of SERS on the silver nanowires arrays different from the SERS on silver film or silver colloids. There are contiguously and non-contact enhanced mechanisms on the silver nanowires array.The change of SERS enhanced mechanisms on gold nanowires array at different temperature was studied by investigating the SERS spectra of probe molecules nicotinic acid (NA) relate with the different temperature on the substrate. In the first temperature range from 110 to 150K, the intensity of the molecule vibration was boosting up with temperature going up, so, the enhancement was ascending. In the second segment of 150-250K, the charge transfer enhancement was primary role. More and more molecules was disengaging from gold nanowires with temperature rising. Fewer and fewer molecules contributed to the effect of SERS, so, the intensity of SERS was diminishing in the range. However, in the range of 250-270K, electromagnetic enhancement became to leading function. The molecules movement was becoming strong with the raise of temperature. A lot of molecules moved to the hot spot where the extremely high enhancement of the electric field observed at the middle area of between each gold nanowies. And the molecules in the hot spot were enhanced largely, the intensity would be enhanced. In the fourth temperature segment from 270 to 350K, the electronic ruleless movement of gold nanowires was intensifying with the raise of temperature. The excitation of LSP produces a high local electromagnetic field in the middle area of between each gold nanowies that relate to the electronic ruleless movement of gold nanowires. The intensity of local electromagnetic field in the hot spot was receding with the enhancement of extent of the electronic ruleless movement. So, the intensity of SERS of the NA molecules which in hot spot would be lowering in the process of temperature from 207 to 350K.On the several kinds of nanowire arrays which silver, titanium, nickel, and aluminum, high-quality SERS spectra of probe molecules of the red dye Sudanâ…¡were obtained. In particular, the SERS spectrum of Sudanâ…¡on an aluminum nanowire array is reported for the first time. Surface-enhanced Raman spectroscopy on the substrate of nanowire arrays is based on the extremely high enhancement of the electric field. observed in the area between the nanowires when excited with a laser beam which was called hot spots. The probe molecules should be enhanced when they are taken into the enhanced electric field between the nanowires. Under these conditions, the most enhanced molecules would not contact the nanowires.The optimal simulation method of Gaussian 03 was. confirmed by studying the computational spectra, which were simulated with six different methods, with the experimental spectrum of NA molecule. The investigation, which the experimenta SERS spectrum of probe molecule NA on the gold nanowires array and stimulant spectra which base on tow different models by the method of DFT-B3PW91/LanL2DZ, indicates that the presence, of contiguously and non-contact enhanced mechanisms on the gold nanowires array.We studied the SERS spectra of PNA on the silver nanowires array at different potential of the substrate. And the stimulant spectra which base on tow different models by the method of DFT-B3PW91/LanL2DZ were obtained. The investigation of the computational spectra and experimental SERS spectra indicates that the change of SERS enhanced mechanisms. It indicated that the hot-spot enhancement playing primary role and the probe molecule adsorbing on the silver nanowires at random in range of the potential from 0.1 to 0V. And in range of the 0-(-0.3) V, the adsorption of molecule transited from random to carboxylic adsorption. And the transformation, which carboxylic adsorption to nitro-adsorption, would occur in the range of the potential from (-0.3) to (-0.5) V. |
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