The far-infrared absorption spectra of myoglobin powder at hydration levels between 3.6 and 42 wt % were
measured with terahertz time-domain spectroscopy and Fourier transform infrared spectroscopy. Absorption
is dominated by the water content, but even the driest specimens have a nearly continuous spectrum without
identifiable sharp features. Inhomogeneous broadening plus the intrinsically high spectral density of vibrational
modes in the region below 2.0 THz apparently combine to obscure the lowest frequency vibrational modes
expected for protein molecules of this size. A continuous absorption spectrum for hydrated protein powders
suggests that the absorption mechanisms are similar to those in liquid water, and hinders the spectroscopic
identification of biomolecules in this frequency range.
Lifetimes of hydrogen and deuterium related stretch modes in Si are measured by high-resolution infrared absorption spectroscopy and transient bleaching spectroscopy. The lifetimes are found to be extremely dependent on the defect structure, ranging from 2 to 295 ps. Against conventional wisdom, we find that lifetimes of Si-D modes typically are longer than for the corresponding Si-H modes. The potential implications of the results on the physics of electronic device degradation are discussed.
In this work, Cu 2 ZnSnS 4 (CZTS) absorber layers were fabricated using a two-stage process. Sequentially deposited Cu-Zn-Sn thin film layers on metallic foils were annealed in an Ar + S 2(g) atmosphere. We aimed to investigate the role of flexible titanium and molybdenum foil substrates in the growth mechanism of CZTS thin films. The Raman spectra and X-ray photoelectron spectroscopy analyses of the sulfurized thin films revealed that, except for the presence of Sn-based secondary phases, nearly pure CZTS thin films were obtained. Additionally, the intense and sharp X-ray diffraction peak from the (112) plane provided evidence of good crystallinity. Electron dispersive spectroscopy analysis indicated sufficient sulfur content but poor Zn atomic weight percentage in the films. Absorption and band-gap energy analyses were carried out to confirm the suitability of CZTS thin films as the absorber layer in solar cell applications. Hall effect measurements showed the p-type semiconductor behavior of the CZTS samples. Moreover, the back contact behavior of these metallic flexible substrates was investigated and compared. We detected formation of cracks in the CZTS layer on the molybdenum foils, which indicates the incompatibility of molybdenum's thermal expansion coefficient with the CZTS structure. We demonstrated the application of the magnetron sputtering technique for the fabrication of CZTS thin films on titanium foils having lightweight, flexible properties and suitable for roll-to-roll manufacturing for high throughput fabrication. Titanium foils are also cost competitive compared to molybdenum foils.
Alpha-lactalbumin (α-la) is one of the major proteins in whey. When partially hydrolysed with Bacillus licheniformis protease, it produces nanotubular structures in the presence of calcium ions by a self-assembly process. This study presents investigation of α-la protein structure during hydrolysis and nanotube formation using optical spectroscopy. Before spectroscopic measurements, nanotubes were examined with microscopy. The observed α-la nanotubes (α-LaNTs) were in the form of regular hollow strands with a diameter of about 20 nm and the average length of 1 μm. Amide and backbone vibration bands of the Raman spectra displayed remarkable conformational changes in α and β domains in the protein structure during nanotube growth. This was confirmed by the Fouriertransform infrared (FTIR) spectroscopy data. Also, FTIR analysis revealed certain bands at calcium (Ca + + ) binding sites of COO À groups in hydrolysed protein. These sites might be critical in nanotube elongation.
The infrared transmission spectrum of Si-doped molecular beam epitaxy ͑MBE͒-grown GaAs epilayers, 2-2.5-m thick, measured in the oblique ͑Berreman͒ geometry, revealed distinct minima in p polarization. Given epilayer thickness Ӷ reststrahlen wavelength, the minima are identified as the zone-center transverse optic phonon (TO) and the high-frequency LO phonon-plasmon coupled mode (ϩ). Analysis of the experimental data yielded free-carrier concentrations ranging from 2.5ϫ10 17 to 1.4ϫ10 18 cm Ϫ3. The same technique with MBE-grown Si-doped In 0.53 Ga 0.47 As epilayers (0.5-1 m thick͒ yielded ϩ modes corresponding to free-carrier concentrations of 8.2ϫ10 16-2.7ϫ10 19 cm Ϫ3. The observations of the transmission minima in the Berreman geometry and their interpretation demonstrate a direct and simple method for deducing free-carrier concentrations over a wide range.
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