• Analytical Science and Technology
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• v.37 no.2
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• pp.114-122
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• 2024

A transmission Raman spectroscopy-based quantitative model, which can analyze the content of a drug product containing naproxen sodium as its active pharmaceutical ingredient (API), was developed. Compared with the existing analytical method, i.e., high-performance liquid chromatography (HPLC), Raman spectroscopy exhibits high test efficiency owing to its shorter sample pre-treatment and measurement time. Raman spectroscopy is environmentally friendly since samples can be tested rapidly via a nondestructive method without sample preparation using solvent. Through this analysis method, rapid on-site analysis was possible and it could prevent the production of defective tablets with potency problems. The developed method was applied to the assays of the naproxen sodium of coated tablets that were manufactured in commercial scale and the content of naproxen sodium was accurately predicted by Raman spectroscopy and compared with the reference analytical method such as HPLC. The method validation of the new approach was also performed. Further, the specificity, linearity, accuracy, precision, and robustness tests were conducted, and all the results were within the criteria. The standard error of cross-validation and standard error of prediction values were determined as 0.949 % and 0.724 %, respectively.

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.170-189
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• 2017

Purpose: This paper presents Raman chemical imaging technology for inspecting food and agricultural products. Methods The paper puts emphasis on introducing and demonstrating Raman imaging techniques for practical uses in food analysis. Results & Conclusions: The main topics include Raman scattering principles, Raman spectroscopy measurement techniques (e.g., backscattering Raman spectroscopy, transmission Raman spectroscopy, and spatially offset Raman spectroscopy), Raman image acquisition methods (i.e., point-scan, line-scan, and area-scan methods), Raman imaging instruments (e.g., excitation sources, wavelength separation devices, detectors, imaging systems, and calibration methods), and Raman image processing and analysis techniques (e.g., fluorescence correction, mixture analysis, target identification, spatial mapping, and quantitative analysis). Raman chemical imaging applications for food safety and quality evaluation are also reviewed.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.404-410
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• 2012

Purpose: The objective of this research was to select high quality cucumber (cucumis sativus) seed by classifying into viable or non-viable one using Raman spectroscopy. Method: Both transmission and back-scattering Raman spectra of viable and non-viable seeds in the range from $150cm^{-1}$ to $1890cm^{-1}$ were collected with a laser illumination. Results: The Raman spectra of cucumber seed showed Raman peaks with features of polyunsaturated fatty acids. The partial least squares-discriminant analysis (PLS-DA) to predict viable seeds was developed with measured transmission and backscattering spectra with Raman spectroscopy and germination test results. Various types of spectra pretreatment were investigated to develop the classification models. The results of developed PLS-DA models using the transmission spectra with mean normalization or range normalization, and back-scattering spectra with mean normalization treatment or baseline correction showed 100% discrimination accuracy. Conclusions: These results showed that Raman spectroscopy technologies can be used to select the high quality cucumber seeds.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.362.1-362.1
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• 2016

InAs nanowires were synthesized by a vapor-liquid-solid method with InAs powder. The composition and crystalline structure of nanowires were confirmed by energy-dispersive spectroscopy (EDS) and high resolution transmission electron microscopy (HRTEM), respectively. The thermal conduction of nanowires was investigated by the optical method using Raman spectroscopy: i.e., the local temperature on nanowire was determined by laser heating. As temperature increased, the Raman peaks are shifted to low frequency and broadened. The temperature dependent Raman scattering experiments was realized on InAs nanowires with different percentages of zinc-blende and wurtzite structure. The temperature dependence on the nanowire structure has been successfully obtained: the phonon scattering was more increased in InAs heretostructure nanowires, compared to the InAs nanowires with homostructure. The result strongly suggests that the thermal conduction can be effectively controlled by ordered interface without any decrease in electrical conduction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.118-125
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• 2008

Single walled carbon nanotubes (SWCNTs) can be modified to produce a new concept of hybrid materials by introducing atoms or molecules inside their cylindrical empty space. Such an endohedral doping of the SWCNTs is expected to decisively alter their electronic transport and mechanical properties, In this study, we purified SWCNTs by three-step purification processes and formed the peapod structure by introducing $C_{60}$ fullerenes inside the SWCNTs. $C_{60}$ molecules were observed to be regularly arranged by transmission electron microscopy. In Raman spectra, the radial breathing mode (RBM) rather than the other modes was significantly affected by the endohedral injection of $C_{60}$. The RBM intensity was more greatly reduced in the large-diameter SWCNTs than the small-diameter ones, Raman spectroscopy is expected to be a key technique for analyzing $C_{60}$-encapsulated SWCNTs.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.161-170
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• 2022

The effect of oxidation time on the characteristics and mechanical properties of spent nuclear fuel cladding was investigated using Raman spectroscopy, tube rupture test, and tensile test. As oxidation time increased, the Raman peak associated with the tetragonal zirconium oxide phase diminished and merged with the Raman peak associated with the monoclinic zirconium oxide phase near 333 cm^-1. Additionally, the other tetragonal zirconium oxide phase peak at 380 cm^-1 decreased after 100 d of oxidation, whereas the zirconium monoclinic oxide peak became the dominant peak. The oxidation time had no effect on the tube rupture pressure of the oxidized zirconium alloy tube. However, the yield and tensile stresses of the oxidized nuclear fuel cladding tube decreased after 100 d of oxidation. The results of the scanning electron microscopy and transmission electron microscopy were represented with the in-situ Raman analysis result for the oxide characteristics generated on the cladding of spent nuclear fuel.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.379-382
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• 2019

Synthesis of gold nanoparticles (NPs) made an aqueous environment via the reduction of HAuCl₄ by ascorbic acid (AC) with the surfactant of polyvinylpyrrolidone (PVP). Highly monodisperse gold particles with size ranges from 4 to 20 nm were prepared in high-yield by pH control. The synthesized gold nanoparticles were analyzed for structural and optical properties using transmission electron microscopy (TEM) and UV-vis spectroscopy. In this study, we could reveal that the prepared nanoparticles exhibited efficient surface-enhanced Raman scattering (SERS) properties, and their SERS activities depends on size.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1579-1582
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• 2011

Alumina particles wrapped in few-layer graphene sheets were prepared by calcining aluminum nitride powders under a mixed gas flow of carbon monoxide and argon. The graphene sheets were characterized by powder X-ray diffraction (XRD), Raman spectroscopy, electron energy loss spectroscopy, and high-resolution transmission electron microscopy. The few-layer graphene sheets, which wrapped around the alumina particles, did not exhibit any diffraction peaks in the XRD patterns but did show three characteristic bands (D, G, and 2D bands) in the Raman spectra. The dye-sensitized solar cell (DSSC) with the alumina particles wrapped in few-layer graphene sheets exhibited significantly improved overall energy-conversion efficiency, compared to conventional DSSC, due to longer electron lifetime.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2071-2076
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• 2009

The single-walled carbon nanotubes (SWCNTs) produced by chemical vapor deposition (CVD) were directly fluorinated with fluorine ($F_2$) gas in a temperature range 20 ~ 400 ${^{\circ}C}$. The surface properties and morphology of the SWCNTs were investigated in terms of fluorination temperature. As a result, Raman spectra showed a pair of bands at 1340 and 1590 $cm^{-1}$ peculiar to disordered $sp^2$-carbons. These results indicated that C-F bonds were formed on the rear surfaces of the nanotubes by fluorination, while the external surfaces as well as the layers between the internal and external surfaces retained their $sp^2$-hybridization. XPS analysis exhibited that fluorine atoms were bonded to carbon atoms on internal surfaces (rear surfaces) of the nanotubes and the amount of fluorine attached on the nanotubes was increased with increasing the fluorination temperature. Consequently, the direct fluorination of carbon nanotubes led to functionalization and modification of pristine nanotubes with respect to surface and morphological properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.930-934
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• 2006

This paper reports a change of carbon nanotubes(CNTs) properties by post-treatment process after growth of CNTs. CNTs were treated by thermal method and solution method, and then investigated in detail using field emission scanning electron microscopy(FE-SEM), high resolution transmission scanning electron microscopy(HR-TEM), RAMAN spectroscopy, and Fourier Transform Infrared Spectrometer (FT-IR). FT-IR spectra showed that the amount of hydroxyl generated on surface of CNTs were changed with post-treatment condition. FE-SEM and TEM images were shown CNTs diameter and density variations were dependent with their treatment conditions. RAMAN spectroscopy was shown that carbon nanotubes structure vary with treatment conditions.