Papers by Keyword: Raman Spectrum

Abstract: ZnO nanorods were successfully synthesized using ZnCl₂ and NaOH as the starting materials without surfactants, template supporting and structure-directing solvent at low temperatures (20 °C 90 °C). X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the crystal structure and surface morphology. Analysis of XRD patterns showed that ZnO clusters are single hexagonal phases of wurtzite structure with no other impurities. Also, TEM images revealed that the size of a single ZnO nanorod was between 32 and 60 nm in diameter and between 470 and 740 nm in length. Furthermore, the ZnO nanorods exhibited significant Raman spectrum optical properties suggesting that they have potential for opto-electronic application.

Abstract: The extreme hardness of Polycrystalline Diamond (PCD) makes it an ideal choice for the machining of hard materials as a cutting tool. Due to the high hardness, fabrication of PCD tools relies on conventional abrasive grinding which suffers from low machining efficiency. Electrical discharge machining (EDM) is an advanced machining process and can be utilised to fabricate complicated PCD tools. High temperature of sintering and EDM processes creates residual stress inside PCD and can result in unmatured failure of PCD tools. This paper analyses the distribution of residual stress in PCD after electrical discharge machining process.

Abstract: Fourier transform (FT) infrared (IR) and Raman spectra of powders in the Biqi capsule, a commercially available national-level combination medicine, are measured to check the information on the most important active ingredient strychnine, which is in fact a highly toxic drug. Referring to the published FTIR absorption and FT Raman spectral data, from our ones we have found that the active ingredient - strychnine in our purchased Biqi capsule really exists and its net content is really not so high and therefore may not cause a serious harm to patients if an approved dosage is eaten. From this study one can see that the IR spectroscopic method is more suitable for this kind of drug identification than the Raman one using the Raman spectroscope in this experiment because strong fluorescent signals excited by lasers on the pharmaceutical excipients and other subordinate active ingredients generally cover up the fingerprint signals of the active ingredient in the drug.

Abstract: IR and Raman spectra of three kinds of mineral drug montmorillonite powders (brands Biqi, Smecta general, Smecta strawberry flavour) commercially available for children are obtained to tell the true from the false through checking the spectral information of the active ingredient (montmorillonite) and pharmaceutical excipients (glucose, saccharin sodium, vanillin and strawberry essence). It is found that net contents of the active ingredient in all three drugs maybe really high and even the cheapest brand is also with a high quality. From this study one can see that the IR spectroscopic method is more suitable for this kind of drug identification than the Raman one using the present Raman spectroscope because strong fluorescent signals excited by lasers on the pharmaceutical excipients can generally cover up the fingerprint signals of the active ingredient.

Abstract: Ce:Mn:LiNbO₃ single crystals with different [L/[N were used for the measurement of Raman spectrum. Each peak appeared in the Raman spectrum was ascribed to the basic vibration modes of the LiNbO₃ crystal according to the basic analysis and the achievements obtained by the earlier researches. The results showed that the peak width at half height (FWHM) of the A₁(TO₁) vibration mode become wide gradually with the increase of the [L/[N. However, the FWHM of A₁(TO₂) and A₁(TO₄) vibration mode decrease with the increase of the [L/[N in the crystal. The FWHM of the E(TO₁) vibration mode was decrease with the increase of [L/[N in the crystal, and also the linear relationship between the FWHM of the E(TO₁) vibration mode and the [L/[N in the crystal. According to the relationship between the [L/[N in the crystal and the FWHM of the E(TO₁) vibration mode for the pure LiNbO₃ crystal, the quantitative relation for the Ce/Mn co-doped LiNbO₃ crystal was revealed by amending the empirical formula for pure LiNbO₃ crystal on the basis of the results measured by ICP-AES. The quantitative relation of the FWHM of the E(TO₁) vibration mode and the [L/[N was given by the Polynomial Fit of the experimental data.

Abstract: High-quality β-Ga2O3 films andβ-Ga2O3 /ZnO/β-Ga2O3 nano composite thin films were fabricated on the sapphire substrates in the high vacuum atmosphere by laser molecular beam epitaxy (LMBE). The lattice structure and optical properties of these films were characterized.With the increase of the sputtering time of ZnO target ,Photoluminescence spectrums and Raman spectrums of the β-Ga2O3 /ZnO/β-Ga2O3 nano composite films were shifted regularly . When the ZnO target was sputtered 30min , the stronggest peak of Raman spectrum was appeared at 267nm . Besides,the composition ofβ-Ga2O3 /ZnO/β-Ga2O3 nano composite film was described .

Abstract: A system based on spectrum analysis for cooking oil testing which combining laser-induced-fluorescence and laser-Raman technology is established. Several oil samples are testing by this system. The measurement results show that, there are rich information for fluorescence and Raman spectrum for the oil samples and there are obvious difference between the fluoresce spectrums for these samples, which can be used as a reference for oil pollution classification and recognition. This technology can be used for in-situ monitoring equipments.

Abstract: In this paper a confocal micro-raman spectrometer was used to study the characteristic change of bamboo charcoal pottery(BCP) during its formation from bamboo-charcoal and clay.The effect of carbonization temperature on the carbon bonds and corresponding modes of vibration was detailedly discussed through analysising raman spectrum of the samples.The results showed that the raman spectra of the samples assumes a typical saddle and have no sharp peak, which belong to the typical spectra of carbon material containing amorphous graphite.BCP was mainly pyrolyzed to aromatic substances at low temperature carbonization stage(less than 973K),but didn't form complete graphite crystallite.At low temperature it is pyrolyzed to generate aromatic component, while at 1073K, it becomes hexagonal planar network aggregate composed of sp3 hybridized C atoms, in this case is shows the structure of microcrystalline graphite.With the rise of baking temperature（973K～1373K）, the valne of R representing disorder began to reduce and the value of La standing for the diameter of microlite started to increase which approves that higher temperature is benefit for the growth of amorphous and the enhancement of graphitizing degree.But BCP was also typical non-graphitizable carbon when heat treatment temperature increased to 1373K.

Abstract: Raman spectra of the geometrically frustrated material sample β-Co2(OH)3Cl have first, to the best of our knowledge, been measured down to liquid nitrogen temperature using the experimental conditions of 10X-objective @ 60 mW and 50X-objective @ 5 mW, respectively. It is found that most Raman bands blueshift with decreasing the sample temperature, agreeing with the thermal expansion effect of common materials, but the Raman spectra from different experimental conditions are slightly different with each other at same temperatures. The difference between them has been explained by the local laser heating effect.

Abstract: Raman (4000-95 cm–1) spectra of the recently identified magnetic geometric frustration material – deformed pyrochlore-structure hydroxyl cobalt bromide β-Co2(OH)3Br polycrystalline sample were measured using 10X and 50X microscopic objectives under different laser powers at room temperature. It is found that the obtained Raman bands at these experimental conditions are slightly different from one another. This phenomenon is caused by the so-called local laser heating effect and can help predict the temperature-dependent spectral behavior of β-Co2(OH)3Br around the room temperature. The Raman spectral experiments down to liquid nitrogen temperature (77 K) confirmed this local laser heating effect.