Search results for "Raman spectroscopy."

The Heme Environment of Mouse Neuroglobin

2001

Neuroglobin (Ngb) is a newly discovered oxygen-binding heme protein that is primarily expressed in the brain of humans and other vertebrates. To characterize the structure/function relationships of this new heme protein, we have used resonance Raman spectroscopy to determine the structure of the heme environment in Ngb from mice. In the Fe2+CO complex, two conformations of the Fe–CO unit are present, one of which arises from an open conformation of the heme pocket in which the CO is not interacting with any nearby residue, and the other arises from a closed conformation where a positively charged residue near the CO group stabilizes the complex. For the Fe2+O2 complex, we detect a single νF…

Inside Cover: Red Blood Cells Polarize Green Laser Light Revealing Hemoglobin′s Enhanced Non-Fundamental Raman Modes (ChemPhysChem 18/2014)

2014

Synthesis and High-Pressure Study of Corundum-Type In2O3

2015

This work reports the high-pressure and high-temperature (HP-HT) synthesis of pure rhombohedral (corundum-type) phase of indium oxide (In2O3) from its most stable polymorph, cubic bixbyite-type In2O3, using a multianvil press. Structural and vibrational properties of corundum-type In2O3 (rh-In2O3) have been characterized by means of angle-dispersive powder X-ray diffraction and Raman scattering measurements at high pressures which have been compared to structural and lattice dynamics ab initio calculations. The equation of state and the pressure dependence of the Raman-active modes of the corundum-type phase are reported and compared to those of corundum (α-Al2O3). It can be concluded that …

Application of micro Raman spectroscopy to industrial FC membranes

2007

Raman spectra of as-received and protonated membranes (Nafion® NRE-212, Fumapem® F-14100 and Fumasep® FAA) were measured with He-Cd and Ar laser. For the first time the Raman and IR spectra are reported of Fumasep membranes. Most of peaks in vibration spectra active in Raman and IR of membranes are interpreted with C-F, C-S, C-O-C, SO3, C-C bonds. The vibration region connected with protons and H-O bond in both types of membranes is found in Raman and IR spectra.

Bichromatic field propagation in a resonant medium: Floquet analysis

2011

We study the propagation of a bichromatic field in a resonant medium. The two modes of the incoming fields are pulsed and delayed with respect to each other. It is shown that in the course of the propagation, new Raman sidebands will be generated. The achievable frequency spacing between the sidebands is determined from experimental data. A numerical example is shown for realistic physical parameters.

Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy

2007

We study high quality molecular-beam epitaxy grown BaTiO3/SrTiO3 superlat-tices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These are due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO3/SrTiO3 layer thicknesses the effective sound velocities within each of the layers are obtained.

Optical absorption and Raman spectroscopy of CuWO4

2010

Th e electronic absorption and Raman spectra of CuWO4 are studied as a function of pressure in the 0 - 20 GPa range. The below-gap absorption bands at 1.15, 1.38 and 1.56 eV correspond to Cu 2+ d-transitions split by the Jahn-Teller distortion of CuO6 (Req = 1.98 A; Rax = 2.39 A; Qθ = 0.47 A). Pressure induces a strong reduction of the JT distortion up to 10 GPa. Above this pressure we observe, by optical absorption and Raman spectroscopy, a first-order phase transition at 11 GPa with phase coexistence in the 10-12 GPa range, as it is confirmed by Raman spectroscopy. The absorption spectra suggest that two different Cu 2+ sites are formed in the high pressure phase, each having rather diffe…

Hydrogen bond studies on n-pentanol and 2-methyl-2-butanol by Raman spectroscopy

1986

Polarized Raman spectra of n-pentanol and its isomer 2-methyl-2-butanol are obtained in the liquid phase near the melting points and at superheated temperatures. The measurements are performed in the intramolecular O-H stretching region. Our analysis of the Raman data provides an interpretation of the spectral features in terms of symmetric O-H bands, originated by various degrees of intermolecular coupling, for which mechanism is different for the two isomers. Temperature dependence of the spectra is also discussed in terms of available structural and dynamical models for these H-bonded liquids.

Investigation on the ganaration process of HO2• radicals by γ-ray irradiation in O2-loaded fumed silica

2013

Abstract We report an experimental investigation on the effects of γ-ray irradiation in three types of fumed silica previously loaded with O 2 molecules. Our data indicate that the main effect of irradiation in these systems is to generate a very large concentration of HO 2 interstitial radicals (about 10 18  molecules/cm 3 ). Furthermore, the number of generated HO 2 was found to be larger in the samples with higher O 2 contents before irradiation. This correlation suggests that HO 2 radicals are induced by reaction of interstitial O 2 molecules with radiolytic H atoms, as previously suggested for O 2 -loaded bulk amorphous silicon dioxide (a-SiO 2 or silica) samples. However, at variance …

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

2016

Photocatalytic water splitting for H2 production and photocatalytic oxidation of 2-propanol, an example of volatile organic compounds, were investigated over TiO2 catalysts loaded with gold and/or ceria. In the water splitting reaction the presence of gold only slightly affected the performance of TiO2 whereas the presence of CeO2 had a more remarkable positive effect. In the 2-propanol oxidation Au/TiO2 was the most active sample in terms of alcohol conversion whereas Au/TiO2-CeO2 exhibited the highest CO2 yield. On the basis of characterization experiments (X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis EDX, surface area measurements, Diffuse Reflectance Spectroscopy (DRS) and …