Insang Yang

Abstract We have measured polarized Raman spectra of MnWO 4 single crystals at low temperatures, and studied the temperature dependence of the various phonon modes. From our Raman studies of the MnWO 4 , a new transition temperature, ∼180 K, was found. We have completely assigned the symmetries of the 18 observed Raman modes of the MnWO 4 , as expected from a group theoretical analysis. These Raman modes have been classified into three groups according to weak, intermediate and strong temperatur

Superconductivity-induced changes in the electronic Raman-scattering response were observed for the $R{\mathrm{Ni}}_{2}{\mathrm{B}}_{2}\mathrm{C}(R=\mathrm{Y},\mathrm{Lu})$ system in different scattering geometries. In the superconducting state, $2\ensuremath{\Delta}$-like peaks were observed in ${A}_{1g},$ ${B}_{1g},$ and ${B}_{2g}$ spectra from single crystals. The peaks in ${A}_{1g}$ and ${B}_{2g}$ symmetries are significantly sharper and stronger than the peak in ${B}_{1g}$ symmetry. The tem

We report polarized Raman measurements on small single crystals embedded in ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ polycrystalline pellets. The measurements show two-mode behavior in the Cu-O bending mode of the ${\mathrm{CuO}}_{2}$ planes (${\mathit{B}}_{1\mathit{g}}$ mode). The increase in frequency with x of the Ba-Ba stretching mode and the chain copper--apical oxygen Cu(1)-O(4) stretching mode i

The specific heat of synthetic melanin, cooled in vitro, has been measured over the temperature range 0.3-3 K. Below 1 K the specific heat has a magnitude and a ${T}^{1.3}$ temperature dependence similar to that of metmyoglobin and of polymer glasses. A phase transition previously reported near 2 K for dried melanin was not reproduced.

Free fatty acid (FFA) is one of the most critical parameters for evaluating the quality of olive oil. In this paper, we present a simple and rapid Raman spectroscopy method for analyzing free fatty acid in olive oil. First, FFA degradation of carotenoids in olive oil is confirmed by analyzing the relative intensity of characteristic vibrational modes and introducing an intensity decrease factor. Second, it is demonstrated that the relative intensity ratio of the two characteristic vibrational mo

We present the results of polarized Raman spectroscopy of hexagonal BaFe 12 O 19 single crystal. The spectra, recorded from 200 to 800 cm –1 and 1100 to 1700 cm –1 in the 20–250 K temperature range, are analyzed on the basis of both crystal vibrations and spin‐waves. In the low wavenumber range, the Γ‐point phonons are observed. In the high wavenumber range, phonon mixings are observed; more interestingly, four modes of spin‐waves are identified in hexagonal BaFe 12 O 19 . Both have not been stu

Abstract Impurity‐induced structural distortion in SmB 6 is suggested by Raman spectroscopy study on impurity‐controlled samples. Significant differences in the Raman spectra of single crystals SmB 6 (6N), synthesized with 99.9999%‐pure boron, and SmB 6 (3N), synthesized with 99.9%‐pure boron, are detected. While no noticeable differences are detected in the X‐ray diffraction of SmB 6 (3N) and SmB 6 (6N), all the Raman phonon modes of the T 2g , E g , and A 1g of SmB 6 (3N) are clearly broader a

Raman spectroscopy has been applied to study unsaturated fatty acid in edible vegetable oils. The relative intensity ratio of characteristic vibrational bands has been investigated as a function of the content of totally unsaturated fatty acid, polyunsaturated fatty acid, and monounsaturated fatty acid. The results suggest the intensity ratio of 1655 cm−1 to 1440 cm−1 or 1265 cm−1 to 1300 cm−1, i.e., a characteristic vibrational band correlated with carbon-carbon double bond in acid chain to a v

Abstract We present the results of the temperature dependence of the Raman spectra of hexagonal HoMnO 3 thin films in the 13–300 K temperature range. The films were grown on Pt(111)//Al 2 O 3 (0001) substrates using the laser ablation method. In the HoMnO 3 thin films, we initially observedseveral broad Raman peaks at ∼510, 760, 955, 1120, and 1410 cm −1 . These broad Raman peaks display an anomalous behavior near the magnetic transition temperature, and the intensity difference of the Raman spe