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Surface-enhanced Raman scattering (SERS) technology, which enables the rapid detection of trace molecules, has gained widespread attention in areas such as pharmaceutical material analysis, identification of hazardous substance residues, and food safety. The response limit of SERS to the detected substances depends on the performance of the substrate and directly affects the final detection effect. In this paper, MoO3-x nanoslots with oxygen vacancy defects were successfully prepared by a simple hydrothermal method with the aim of increasing the specific surface area of the substrate and its ability of photoinduced charge transfer between the substrate and the detected substances. The electronic structure, optical properties and surface chemical environment of the MoO3-x nanoslots were analyzed by a combination of X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared spectroscopy (FT-IR). Three organic dye molecules, rhodamine 6G (R6G), crystalline violet (CV) and rose red B (RhB), were detected using the MoO3-x nanoslots as SERS substrates, and the experimental results show that the detection limit of R6G could reach 10 -10 mol/L, and it has better Raman-enhancing activity compared with the same type of semiconductor substrates. [ABSTRACT FROM AUTHOR]

The 14 mm x 12 mm AlN single crystal is synthesized by the homoepitaxial physical vapor transport method. The crystal sample sliced from the boule is processed by lapping and chemical mechanical processes (CMP). The sample is characterized by Raman spectrometer, high resolution X-ray diffractometer, X-ray photoelectron spectrometer and photoluminescence spectrometer. The Raman results show that the full width at half maximum (FWHM) of the E2 (high) phonon mode of Raman spectrum is 3.3 cm-1 in the central region of the sample, and the FWHM of the E2 (high) phonon mode of Raman spectrum is 4. 3 cm-1 in the edge of the sample, the AlN single crystal exhibits high crystal quality. The FWHM of the X-ray rocking curve increase to 100" in the central region of the homoepitaxial growth crystal, while the FWHM of the X-ray rocking curve is 205" in the edge region of the homoepitaxial growth crystal, which indicates defects exist in the crystal. XPS results show that there are C, O, Si impurity elements in the crystal, and the atomic concentration of the impurities is 0.74%, 1.43% and 2.14%, respectively. It is found that the mainly oxygen impurities exist in the crystal in the form of Al--O, N--Al--O bonding. PL spectra show that crystal contains VAl-ON compound defect and VAl point defect. [ABSTRACT FROM AUTHOR]

As a kind of excellent host material for solid-state lasers, GdScO3 crystal has attracted more and more attention. In this paper, Yb,Ho∶GdScO3 crystal with the size of ϕ30 mm × 50 mm was firstly grown by Czochralski growth method. The powder diffraction data were obtained by X-ray diffraction, and the structure parameters were fitted by GSAS software. Raman spectra were measured. In the range of 100 to 700 cm-1, there are 18 Raman vibration peaks were observed. The spectral properties including transmission and emission of Yb,Ho∶ GdScO3 crystal were characterized. The center of the strongest absorption band is at 975 nm, which comes from the transition of Yb3 + ∶2 F7/2 →2 F5/2. The absorption cross section of Yb3 + were calculated and the values at 940, 975 nm are 0. 31 × 10 -20 and 0. 42 × 10 -20 cm2. The transition intensity parameter (Ωt) of Ho3 + was calculated by Judd-Ofelt theory, Ω4 / Ω6 is 2. 04. And spectral parameters such as radiation transition probability, energy level lifetime and fluorescence branching ratio were calculated. The results show that Yb,Ho∶GdScO3 is a promising candidate material for 2 ~3 μm laser crystals because of its excellent luminescence properties. [ABSTRACT FROM AUTHOR]

The current measurement of soil properties can be limited in the variable-rate fertilizer application using soil analysis, due to the labor-intensive and time-consuming in the laboratory. Rapid, non-destructive soil detection is highly required to be developed using visible-infrared spectroscopy. Among them, Raman spectroscopy can be used to detect the vibrational properties of molecules, due to the fast, non-invasive, small sample treatment, and free interference from water in various fields. Nevertheless, incident light is also required to induce the Raman scattering, in order to compensate for the information with infrared spectroscopy. Therefore, the Raman scattering measurement can be widely used in the composition and dynamic process of soil minerals, bacteria colonies, and humic fraction in soil sensing. However, it is still lacking on the fluorescence effect of soil in the sensing of soil nutrients, which can weaken the Raman signals and the information extraction for the quantitative analysis. Raman spectroscopy has been introduced into some novel measurement techniques to improve the signal-to-noise ratio in recent years, including the shifted excitation Raman difference spectroscopy (SERDS), confocal Raman microscope, and surface-enhanced Raman spectroscopy (SERS). Meanwhile, both aliphatic and aromatic compounds are Raman active in the quantitative and qualitative detection of soil organic matter (SOM). Moreover, many phosphorous compounds in soil are also Raman active, leading to low prediction accuracy using visible-near infrared spectroscopy. In this review, the research progress was proposed on the Raman spectroscopy in the rapid detection of soil nutrients, together with the technical means in suppressing soil fluorescence interference to obtain high-resolution Raman signals. In the detection of SOM, the fusion of infrared and Raman spectral data significantly improved the prediction accuracy of 43% in the root mean square error (RMSE). In addition, the SERDS technique was used to detect the SOM of 33 soil samples. The reconstructed Raman peaks of soil minerals and organic materials obtained an excellent prediction accuracy of the SOM, with the determination of coefficient R 2=0.82, and the residual prediction deviation RPD=1.81. Raman spectroscopy was used to detect the water-soluble nitrogen in the soil solution, whereas, the SERS was to enhance the Raman peaks. An excellent correlation was obtained between the concentration of water-soluble nitrogen and the SERS data (R²=0.91). Research showed that Raman spectroscopy can be an effective tool to identify the different phosphate species in soil. Wavelet packet decomposition of Raman spectra was used to predict the phosphorus concentration in the phosphate-mixed soil with the SOM leached, where the accuracy of the regression model reached R²=0.94. Since the measurement area of Raman spectroscopy depended mainly on the spot size of the laser that irradiated on the sample surface, the spatial variability of the soil sample can be difficult to focus on the target substance. The effective Raman signal of soil nutrients can be obtained with high spatial resolution while suppressing the interferences from the background light. The combination of SERDS and micro-Raman technologies can be expected to serve as an in-situ measurement of soil nutrients. Reducing the redundant variables is crucial when applying spectral fusion since interpretability and reproducibility of the prediction model are paramount in the sensor development using Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Hexagonal Y1 - x Hox Mn0.8 Fe0.2O3 polycrystalline samples were synthesized by high-temperature solid-state reaction method. The effects of Ho3+ doping on microstructure and magnetic properties of YMn0.8 Fe0.2O3 were investigated in this paper. X-ray diffraction (XRD) and Raman spectra (RS) show that all samples are of single-phase hexagonal structure without another impurity phase. When the doping concentration (x) of Ho3+ is lower than 0.15, the lattice constants, unit cell volume and bond length between the Mn--O of the samples decrease with x increasing. The decrease of the lattice constants may be related to the interaction between the Mn3+ / Fe3+ 3d orbital and the Ho3+ 4f orbital, resulting in lattice distortion and electron loss. The displacements of the rare-earth atoms at the A-site relative to the plane and the inclination of the MnO5 bipyramids are suppressed with increasing doping concentration, which is demonstrated by the shift deviations of the rare-earth atoms and the variations of the Raman phonon modes. At the same time, the trimerization of Mn3+ at the B-site is weakened. The magnetic properties of the samples were measured using the superconductor quantum interference device (SQUID). Results show that the antiferromagnetic (AFM) order decreases upon Ho3 + doping, consistent with the reduced superexchange interaction between Mn3+ --O2- --Mn3+. The AFM transition temperature TN decreases. Besides, the magnetization of the samples and the weak ferromagnetic (WFM) order at low temperature are significantly enhanced, which is attributed to the suppressed magnetic resistance behavior of the system and the ferromagnetic order generated by the spin exchange interaction between Ho3+ --O2- --Mn3+. These provide an idea for us to further explore room temperature multiferroic materials. [ABSTRACT FROM AUTHOR]

Surface Enhanced Raman Scattering（SERS）is a vibration spectroscopy technology，which can directly identify target analytes and has a wide range of applications in chemistry，physics，materials， biomedicine and other fields. Ordered SERS substrate refers to the SERS substrate composed of regularly arranged nanostructures，which has good uniformity and reproducibility. In this review，surface enhanced Raman scattering and SERS substrates are introduced，and the self-assembly method，lithography technology and template-assisted method for preparing ordered SERS substrates are emphatically described. [ABSTRACT FROM AUTHOR]

By combining anodic oxidation with photo-reduction method，a uniform，stable and recyclable surface enhanced Raman scattering （SERS）-active substrate composed of well-ordered Ag nanoparticles decorated on TiO2 nanotube arrays （TiO2NTAs/Ag） is obtained. The composition and structure of the TiO2NTAs/Ag are characterized using X-ray powder diffraction （XRD），X-ray photoelectron spectroscopy （XPS），UV-Vis diffuse reflection spectrum（UV-Vis DRS），surface enhanced Raman scattering spectroscopy （SERS）and scanning electron microscope（SEM）measurements. The SERS response of the TiO2NTAS/Ag array to tetracycline hydrochloride（TC-HCl）is further studied，which exhibits superior sensitivity for SERS detection of TC-HCl，and the detection limit could reach 1 × 10－14 mol/L in water. In addition，the TiO2NTAs/Ag substrate exhibits excellent degradation activity for TC-HCl under light and could be recycled for at least 8 times. It shows a potential application in SERS detection and degradation of organic contaminants in environment. [ABSTRACT FROM AUTHOR]

BACKGROUND: The Marange diamond deposit in Zimbabwe is characterized by producing mixed-habit (octahedral and cuboid) diamonds. Graphite inclusions in these diamonds only exist in cuboid sectors. The morphological and distributional characteristics of graphite inclusions and the abnormal birefringence and strain characteristics of diamonds can reflect the geological process experienced by diamonds from the beginning of crystallization to being transported to the Earth’s surface. Therefore, the study of diamonds and graphite inclusions in Zimbabwe can provide comparative data for diamonds from other deposits. Besides, due to the peculiarity of growth habits, detailed analysis would be of great value to help understand the behavioral differences of diamonds with different growth habits in geological processes. OBJECTIVES: To determine if graphite inclusions in Zimbabwean diamonds are syngenetic or epigenetic, and to reveal the relationship between graphite inclusions and the infrared absorption spectrum, Raman scattering spectrum as well as birefringence and strain characteristics of diamonds. METHODS: The growth structure and growth sectors of Zimbabwean diamonds were observed by DiamondViewTM image system. The morphological and distributional characteristics of graphite inclusions and abnormal birefringence in diamonds were analyzed by scanning electron microscopy (SEM) and polarized light microscopy. Analysis of distribution and relative concentration of impurity elements in different growth sectors was conducted by infrared spectroscopy. Strain characteristics of diamonds in different growth sectors were analyzed by Raman spectroscopy and projection diagram of corresponding results. RESULTS: Graphite inclusions in cuboid sectors of Zimbabwean diamonds were syngenetic-epigenetic inclusions located in directional elliptical cracks. According to infrared spectra of different growth sectors, cuboid sectors showed stronger infrared absorption related to elemental hydrogen, while octahedral sectors showed stronger absorption related to elemental nitrogen. This enrichment of different impurity elements leading to abnormal birefringence was mainly related to cracks and different growth sectors in diamond. The Raman shift of LO=TO band in octahedral sectors was 1332.05-1332.20 cm-1, the FWHM was 4.21-4.37 cm-1, which corresponded to stress of 0.06-0.27 GPa. The Raman shift of LO=TO band in cuboid sectors was 1331.93-1332.47 cm-1, the FWHM was 3.67-4.08 cm-1, which corresponded to stress of 0.01-0.64 GPa. In general, the residual stress and strain were greater in cuboid sectors. CONCLUSIONS: The determination of the orientation of graphite inclusions in mixed-habit diamonds in Zimbabwe, provides new evidence to prove their syngenetic-epigenetic nature, and reveal the difference in the strain characteristics of diamonds in the two growth regions. This research is helpful for understanding the formation environment of diamonds in Zimbabwe and of different diamonds. The differences in physicochemical properties are of great significance. [ABSTRACT FROM AUTHOR]

Graphene is a zero-gap semiconductor with low work function and high leakage current which limit its applications. Doping of nitrogen is one of the ways to tailor the properties of graphene. However, there remain some defects, such as the low nitrogen content and poor controllability. In order to enhance the content of nitrogen and control the bonding characters to embed nitrogen atoms inside the carbon lattice, solid-state sources (melamine) and gas-state sources (methane) were used to prepare nitrogen doped graphene (NG) films. The preparation time, the dosage of melamine and temperature were set as tunable parameters. The morphology of NG, the content of nitrogen (mass fraction of nitrogen atoms) and the bonding characters for the embedding of N atoms were studied. The results indicated that the preparation process of NG films was involved with nucleation, growth and aggregation. Proper temperature (990 °C) was conductive for the improvement of the content of nitrogen. Pyrrolic N was produced at high temperature (＞1 000 °C), while graphitic N was on the opposite. With increasing the dosage of melamine, the content of nitrogen was increased and then decreased with the maximum value of 6.98%. The content of Pyridinic N will be elevated with increasing the amount of melamine. Compared with graphene, NG films were capable of detecting the Raman signals from Rhodamine B molecules even at the concentration as low as 10−5 mol/L. [ABSTRACT FROM AUTHOR]

Nanoparticle technologies are significantly impacting the development of both therapeutic and diagnostic agents. At the intersection between treatment and diagnosis, interest has grown for combining both paradigms into clinically effective formulations. In this study, gold nanoparticles based chain like nanostructure were developed by template method for theranosties of cancer. This system could enhance Raman scattering signals for disease diagnosis. The cancer cell exhibited much higher cellular uptake due to the big aspect ratio of chain like nanostructure. This system had potential to deliver diagnostic agents and drugs to tumor tissue for diagnosis and therapy of tumor. [ABSTRACT FROM AUTHOR]

Pesticide residue is one of the main risk factors affecting food safety. Traditional methods for the determination of pesticide residue require costly and large-scale equipments, which can’t meet the needs of on-site and real-time detection. In recent years, with the development of the preparation and functionalization technologies, nanomaterials have been extensively studied for the determination of pesticide residue. Various nanosensors were fabricated by combination of nanomaterials with fluorescence, colorimetric, surface-enhanced Raman scattering and electrochemical method, which enhanced the specificity and senditvity largely, and achieved a breakthrough of rapid detection technology. Herein, the research progress on application of four main types of nanosensors for rapid detection of pesticide residue is reviewed, and the prospects are discussed. The fabrication of portable nanosensor with high selectivity, excellent anti-interference ability and broad application prospect will continue to be a main research focus. [ABSTRACT FROM AUTHOR]

Monocrystalline silicon is etched by alkaline solution to prepare an ordered pyramid structure. A certain thickness of gold film is plated on the surface of the silicon-based pyramid by magnetron sputtering as a surface-enhanced Raman scattering active substrate. The surface morphology and optical properties of the samples were characterized by SEM and UV-Vis spectrophotometer. With methylene blue as the probe molecule, more Raman characteristic peaks were detected. Raman spectra of melamine and pesticide diphenoquinone were detected by improving silicon fund nanosubstrate. The experimental results show that the prepared silicon fund nanosubstrate has potential application prospects in food safety and pesticide detection. [ABSTRACT FROM AUTHOR]

In order to help the undergraduate students to acquire a better understanding of the principles of the fluorescence analysis and improve their comprehensive analysis and problem-solving skills, the content and teaching process of the Vitamin B2 fluorescence experiment were redesigned. The basic theory was intensified through the identifications of the Raman and Rayleigh scatterings ； the functions of the component parts of the instrument were better comprehended by adjusting parameters like the pass band, high voltages of photomultiplier tube and so on. Through the well-designed question and answer session with specific data and experimental operation, the learning initiative and creativity of the students were fully developed. The ability of analyzing and solving problems was increased and the teaching quality of the fluorescence experiment was effectively improved indeed. [ABSTRACT FROM AUTHOR]

A rapid detection method was established for chemicals illegally added in Antipsychotic traditional Chinese medicine (TCM). The method used thin layer chromatography ( TLC ), and combined with surface-enhanced Raman scattering ( SERS). After optimizing several experimental factors of the silver colloid, detection method of D-SERS and intensity of laser, TLC was used to separate TCM matrixes and four types of adulterated chemicals such as perphenazine, carbamazepine, risperidone and sulpiride. Trichloromethane, methanol and water ( 8 - : 0.2 ) was used as the mobile phase and TCM was located under UV 254 nm, then the separated trace substances in TLC plant were tested by SERS method. In conclusion, the established specific and sensitive TLC-SERS technique could be used to detect the chemical adulteration in antipsychotic drugs of Chinese medicine, and the lowest limit of detection was to 0. 02 mg/mL. Compared with the HPLC method, this method was simple, rapid and without sample pretreatment. In this case, the TLC-SERS method has potentially broad application in the fields of on-line fast screening. [ABSTRACT FROM AUTHOR]

Heavy metals are harmful to the vast majority of organisms including human. However, heavy metals can be gradually accumulated in plants and animals by the food chains. So the heavy metal pollution in the environment will threaten human health if we do not control the pollution. Heavy mental ions in plants always have chelation with the organic molecular groups in resin, and the complex has the Raman spectroscopy. Therefore heavy mental ions in plants can be indirectly detected by using Raman technique basing on the chelation. Vetiver grass can grow up in the soil with heavy metal pollution. It has the strong tolerance of heavy metals. Because of that, vetiver grass becomes one of the ideal plants for the conservation and phytoremediation of heavy metal pollution in soil and water. After preprocessing resin by HCl and NaOH, we compared copper adsorption rate for different types of resins. Based on the results of comparison, we chose ion exchange resin D113 to absorb copper. We then compared different oscillation time, solution pH, solution temperature for their impact on copper adsorption so that the best adsorption conditions could be determined. It showed that changing the temperature of solution had a little impact on resin adsorption rate. Therefore, experiments for copper was conducted at the conditions: at room temperature, pH value from 5 to 7, and the oscillation time 80 min. The adsorption rate can reach 99.54% in these conditions. An application of confocal microprobe Raman spectroscopy fast detecting heavy metal copper in vetiver grass roots was proposed, and partial least squares (PLS) regression combined with different data preprocessing methods (Savizky-golay smoothing, Baseline correction, first derivative, second derivative, Detrended fluctuation analysis) was used to develop quantitative models of heavy metal copper in vetiver grass roots. Calibration models were evaluated by an independent predictor of adaptive sample set. With the first derivative preprocessing, the best prediction model of heavy metal copper in vetiver grass roots was achieved with the external validation correlation coefficient of 0.78 and root mean square error of prediction (RMSEP) of 23.46% separately. The study showed that the fast detection of heavy metal copper in vetiver grass roots using Raman spectroscopy technique and the D113 resin adsorption technique was feasible. The calibration and validation statistics obtained in this study showed the potential of Raman spectroscopy to predict heavy metal in the root of vetiver grass. Although the accuracy of model with this method was lower than the routine analysis, Raman spectroscopy could be used as a fast and simple tool to diagnose the content of heavy metal in vetiver grass approximately. Overall, Raman spectroscopy can be used as a reference method for diagnosing the content of heavy metal in vetiver grass, but the accuracy needs to be improved. [ABSTRACT FROM AUTHOR]

The entanglement of multiple spatially separated remote quantum nodes is the foundation for constructing quantum information networks. Moreover, the entanglement between multiple quantum nodes can also be applied to distributed quantum computing and quantum precision measurement. It is imperative to achieve higher entanglement between multiple quantum nodes. In this paper, a scheme is proposed to achieve entanglement of three distant atomic ensembles through cavity enhancement via interference and real-time feedforward. In this scheme, only three sets of cavity enhanced atomic systems are required. The optical resonant cavity enhances the interaction between light and atoms, improving the efficiency of the Stokes and anti Stokes light fields generated through stimulated Raman scattering, and achieving high entanglement between light and atoms. Under this premise, the entanglement between three remote quantum nodes can be achieved through interference and real-time feedforward. This method can be extended to larger and even more complex quantum information networks, thus having potential applications in quantum information science. [ABSTRACT FROM AUTHOR]