Polarized Absorption Research Articles

Spectroscopic properties of ErAl3(BO3)4 single crystal

Single crystal of ErAl3(BO3)4 was grown and its structure was studied. Polarized absorption spectra of ErAl3(BO3)4 single crystal were measured in the spectral range 1670–330nm (6000–30000cm−1). The Judd–Ofelt spectroscopic parameters have been determined: Ω2=4.87×10−20cm2, Ω4=2.49×10−20cm2, Ω6=2.72×10−20cm2. These parameters have been used to calculate the radiative transition probabilities, the multiplet luminescence branching ratios and the fluorescence life times of the manifolds. The luminescence spectra due to transitions 2H11/2→4I15/2 (526nm), 4S3/2→4I15/2 (548nm), 4F9/2→4I15/2 (662nm), 2H11/2→4I13/2+4I9/2→4I15/2 (800nm) and 4S3/2→4I13/2 (855nm) were recorded in α, σ and π polarizations. The most intensive luminescence belonged to 4S3/2→4I15/2 transition (548nm).

Spectroscopic properties and laser performance of an Yb0.006:Y0.923Lu0.071VO4 mixed crystal

Polarized absorption and emission spectra and continuous-wave laser performance of a new Yb0.006:Y0.923Lu0.071VO4 mixed vanadate crystal are studied. For π polarization the maximum absorption and emission cross sections are 5.0 × 10−20 cm2 and 8.6 × 10−20 cm2, respectively. Continuous-wave laser operation is demonstrated at room temperature, displaying typical bistable behavior. A maximum output power of 1.90 W is generated with an optical-to-optical efficiency of 29%, while the slope efficiency is 42%.

Spectroscopic analysis of efficient laser material Ho^3+:YVO_4

The spectroscopic properties of Ho3+-doped YVO4 were studied at cryogenic temperatures in the 2 µm spectral region to clarify recent observations of efficient dual-wavelength laser operation in this material. Energy levels of the 5I7 and 5I8 manifolds were determined from low-temperature absorption and fluorescence measurements. Polarized absorption cross sections were measured, and stimulated emission cross sections were determined using the reciprocity method coupled with Fuchtbauer-Ladenburg calculations. The observed laser emission wavelengths were at 2054.2 nm and 2068.5 nm. At 80 K, radiative lifetimes for the 5I7 manifold were calculated to be 3.6 ms, and fluorescence lifetimes were measured to be 2.9 ms, indicating a quantum efficiency of ~80%. Analysis of the gain cross section at 80 K and 100 K showed that the laser output wavelength is very susceptible to minor changes in temperature.

Growth and laser operation of Yb-doped mixed vanadate crystals

Abstract Three mixed Yb t Y x Lu 1− t − x VO 4 crystals, with x =0.923, 0.848 and 0.708, were grown by the Czochralski method. Polarized absorption spectra and fluorescence spectra were studied at room temperature. The absorption cross sections at 985 nm are 5.46×10 −20 cm 2 , 5.70×10 −20 cm 2 , and 5.97×10 −20 cm 2 , respectively, for π polarization. The broadest bandwidth of the absorption spectrum reaches up to 38.22 nm for σ polarization. Fluorescence lifetimes are almost the same (0.331 ms, 0.327 ms and 0.329 ms). CW laser operation was achieved at room temperature with a maximum output power of 1.19 W at a pump power of 8.8 W.

Spectral properties of Ho3+/Tm3+ co-doped β′-Gd2(MoO4)3 crystal as laser gain medium around 2.0 μm

Ho3+/Tm3+ co-doped β′-Gd2(MoO4)3 single crystal was investigated as gain medium for Ho3+ laser around 2.0μm. Polarized absorption and fluorescence spectra of the crystal were measured. Polarized spectral parameters of Ho3+ ions in the crystal were calculated and the gain curves around 2.0μm were estimated. The fluorescence decay curves for Tm3+ and Ho3+ ions related to the 2.0μm laser were measured and analyzed. The distinct coupled decay behavior for the Ho3+/Tm3+ co-doped system embodies the existence of energy transfer between Tm3+ and Ho3+ ions.

Calycosin entered HUVECs and ameliorated AGEs-promoted cell apoptosis via the Bcl-2 pathway

Endothelial cell (EC) apoptosis plays a pivotal role in the progression of diabetic complications. Abundant studies have demonstrated the pivotal role of advanced glycation end products (AGEs) on the development of diabetes. The aim of the present study was to investigate the effect of calycosin, a phytoestrogen, on AGEs-induced human umbilical vein endothelial cell (HUVEC) apoptosis. Fluorescence polarization and fluorescence absorption assays indicated that calycosin interacted with AGEs in a time-dependent manner. Further studies found that calycosin entered the cells as detected by HPLC. The MTT method demonstrated that calycosin ameliorated AGEs-induced HUVEC apoptosis in a dose-dependent manner, and statistical significance was observed at 1 × 10(-8) M of calycosin; this behavior was further demonstrated by acridine orange/ethidium bromide staining in that the presence of calycosin dramatically reduced AGEs-induced red staining in HUVECs. Further studies found that pre-incubation with calycosin at 1 × 10(-8) M dramatically increased anti-apoptotic Bcl-2 while decreased pro-apoptotic Bax and Bad expressions as detected by immunocytochemistry, and the effect of calycosin on rebalancing the ratio of Bcl-2/Bax was more significant than that of its glycoside, calycosin-7-O-β-D-glucopyranoside (CG). Furthermore, calycosin slightly reversed AGEs-induced cell oxidative stress at 1 × 10(-8) M, but its antioxidative stress effect was less significant than that of CG. The present study strongly indicates that calycosin can enter the cell and modulate endothelial cell dysfunction by ameliorating AGEs-induced cell apoptosis.

The microwave absorbing properties of SmCo attached single wall carbon nanotube/epoxy composites

The SmCo nanoparticles attached single wall carbon nanotubes (SmCo attached SWCNTs) were prepared by hydrogen dc arc discharge method using 2:17 type SmCo permanent powder as catalyst. The SmCo attached SWCNT/epoxy composites with different doping ratios were investigated in the frequency region of 2–18GHz. The complex permittivity and permeability of the SmCo attached SWCNT/epoxy composites were calculated. The reflection loss properties were simulated by transmission line theory and the microwave absorptive mechanisms were discussed. The results indicate that, due to the better interfacial polarization absorption mechanism of SmCo attached SWCNTs and the electromagnetic (EM) matching of magnetic loss and dielectric loss, the microwave absorption properties of SmCo attached SWCNT/epoxy are evidently improved. When the SmCo attached SWCNTs is doped by 1wt%, the composite display a larger and wider absorption peak, and the bandwidth of the reflection loss below −20dB is larger than 6GHz with the thickness of 3.3mm. It is expected that the new SmCo attached SWCNT/epoxy composites will be a good microwave absorbing material for the applications in X band, Ku band, or even K band.

Growth, thermal properties and laser operation of Nd:Ca_3La_2(BO_3)_4: A new disordered laser crystal

A novel disordered laser crystal Nd:Ca(3)La(2)(BO(3))(4) is characterized including its crystal growth, structure, thermal properties, inhomogeneously broadened spectra, and laser performance, which result that this crystal should be a promising gain material for the high-power ultrashort pulsed neodymium laser. The complete set of anisotropic thermal properties were systematically studied for the first time. It has been found that thermal contraction happens in the c direction and all the thermal conductivities increase with temperature, indicating a glass-like behavior. Polarized absorption and fluorescence spectra of Nd:Ca(3)La(2)(BO(3))(4) crystal were measured at 298.15 K and 77.3 K, respectively. The results show that both the absorption and the emission spectra of Nd(3+) have been inhomogeneously broadened, and thus it is very promising to be used in laser systems to produce femtosecond pulses. CW laser operations at 1.06 μm along the three crystallographic directions has been demonstrated for the first time. A maximum power of 1.08 W with an optical conversion efficiency of 10.6% and slope efficiency of 12.4% was achieved in the a-cut sample.

Charge modulation infrared spectroscopy of rubrene single-crystal field-effect transistors

Polarized absorption spectra of hole carriers in rubrene single crystal field-effect transistors were measured in the infrared region (725–8000 cm−1) by charge modulation spectroscopy. The absorptions, including the superimposed oscillatory components due to multiple reflections within thin crystals, monotonically increased with decreasing frequency. The spectra and their polarization dependences were well reproduced by the analysis based on the Drude model, in which the absorptions due to holes in rubrene and electrons in the gate electrodes (silicon), and multiple reflections were fully considered. The results support the band transport of hole carriers in rubrene.

Characterization of Poly(N-vinlycarbazole) Blending with Different Composition by Using Polarized Electronic Spectroscopy

Polarized absorption and dielectric spectra of blended poly (N-vinlycarbazole) (PVK) with polyvinylpyrrolidone (PVP) in different composition ratiosare investigated. Polymer coating was carried out using doctor blade technique on a quartz substrate. The polarized optical source was produced by using the uv-vis sheet polarizer. The polarized absorption and dielectric spectrum for parallel and perpendicular reveal that there are different significant results obtained between PVK and PVP with various polymer compositions.The polarized optical properties such aspolarization, ρwere calculated.These spectra indicate that the anisotropic properties of each polymer blends is different from each other.

Structural Estimation of Functional Organized Molecular Films by Using Polarized Near-edge X-ray Absorption Fine Structure Spectroscopy

軟X線の吸収と偏光性を活用する，偏光X線吸収端近傍微細構造（NEXAFS）分光法により，単分子層レベルから数層膜程度までの超薄有機組織化膜中の分子配向，並びに官能基配向解析について，最新のトピックスをもとに概説する．特に本稿においては，分子構造中に特徴的な官能基を複数有する高分子化合物（含・共重合体）にフォーカスを当て，サブ・ナノ空間における極限構造の解明に対する取り組みに関し，紹介を行う．

Experimental observation of left polarized wave absorption near electron cyclotron resonance frequency in helicon antenna produced plasma

Asymmetry in density peaks on either side of an m = +1 half helical antenna is observed both in terms of peak position and its magnitude with respect to magnetic field variation in a linear helicon plasma device [Barada et al., Rev. Sci. Instrum. 83, 063501 (2012)]. The plasma is produced by powering the m = +1 half helical antenna with a 2.5 kW, 13.56 MHz radio frequency source. During low magnetic field (B < 100 G) operation, plasma density peaks are observed at critical magnetic fields on either side of the antenna. However, the density peaks occurred at different critical magnetic fields on both sides of antenna. Depending upon the direction of the magnetic field, in the m = +1 propagation side, the main density peak has been observed around 30 G of magnetic field. On this side, the density peak around 5 G corresponding to electron cyclotron resonance (ECR) is not very pronounced, whereas in the m = −1 propagation side, very pronounced ECR peak has been observed around 5 G. Another prominent density peak around 12 G has also been observed in m = −1 side. However, no peak has been observed around 30 G on this m = −1 side. This asymmetry in the results on both sides is explained on the basis of polarization reversal of left hand polarized waves to right hand polarized waves and vice versa in a bounded plasma system. The density peaking phenomena are likely to be caused by obliquely propagating helicon waves at the resonance cone boundary.

Self-Q-switched Cr,Nd:ReVO4 (Re=Gd, Y) crystal lasers

Self-Q-switched Cr,Nd:ReVO4 (Re=Gd, Y) crystallasers are demonstrated. The spectroscopic and self-Q-switched laser properties of Cr,Nd:ReVO4 arestudied. Polarized absorption spectra weremeasured at room temperature, which showed thatthe absorption bands display polarization characterand an absorption band of Cr5+ ions at 1110 nmenables the crystals to be self-Q-switched lasermaterials. The maximum pulse energy are achievedto be 1.12 μJ with Re=Gd , and the shortest pulsewidth is 85.8 ns with Re=Y. The results show thatCr,Nd:ReVO4 crystals are new potential self-Qswitchedlaser materials.

Role of novel oxazocine derivative as corrosion inhibitor for 304 stainless steel in acidic chloride pickling solutions

Inhibition of 304 stainless steel corrosion in acidic chloride pickling (1.0 M HCl) solutions by newly synthesized oxazocine derivative 4 as a corrosion inhibitor have been studied using weight loss, potentiodynamic polarization, and atomic absorption spectroscopy investigations. Potentiodynamic polarization curves show that the inhibitor behaves as a mixed-type. The adsorption of the inhibitor on the metal surface in the acid solution was found to obey Langmuir’s adsorption isotherm. The inhibition mechanism of the investigated inhibitor was discussed in terms of its adsorption on the metal surface. The relationship between the molecular structure and the inhibition efficiency was elucidated by quantum chemical calculations.

Room temperature passive mode-locked laser based on InAs/GaAs quantum-dot superlattice

Passive mode-locking is achieved in two sectional lasers with an active layer based on superlattice formed by ten layers of quantum dots. Tunnel coupling of ten layers changes the structural polarization properties: the ratio between the transverse electric and transverse magnetic polarization absorption coefficients is less by a factor of 1.8 in the entire electroluminescence spectrum range for the superlattice.

Optical Imaging and Absolute Absorption Cross Section Measurement of Individual Nano-objects on Opaque Substrates: Single-Wall Carbon Nanotubes on Silicon

Optical detection of an individual single nano-object on an opaque substrate and direct determination of its absorption cross section is demonstrated using reflective spatial modulation spectroscopy. This method is applied to optical imaging and investigation of individual single-wall carbon nanotubes in the 1.6 nm diameter range on silicon substrates, which are also individually characterized by atomic force microscopy, scanning electron microscopy, and in situ micro-Raman spectroscopy. Absorption cross sections on the order of 10–17 cm2 per carbon atom are measured for the investigated semiconducting carbon nanotubes, with a light polarization absorption anisotropy of about 2.

Spectroscopic characterization and diode-pumped 910 nm laser of Nd:LiLuF4 crystal

Polarized absorption and fluorescence spectra Nd3+-doped LiLuF4 single crystal were investigated. The peak emission cross section at 905 and 910 nm are 0.97 × 10−20 and 0.82 × 10−20 cm2, respectively. Two samples with different dimensions were tested in the laser experiments. With a laser-diode as the pump source, a maximum 1.17 W laser output at 910 nm has been obtained with a slope efficiency of 16.3% with respect to the pump power.

Spectra energy levels and symmetry assignments of Sm3+ doped in YAl3(BO3)4 single crystal

Single crystals of YAl3(BO3)4 doped with 5% Sm3+ were grown by spontaneous nucleation from K2Mo3O10 and B2O3 flux. Photoluminescence spectra at room and low temperatures were measured. Four emission transitions have been observed from the 4G5/2 excited state to the lower lying states 6H5/2, 6H7/2, 6H9/2 and 6H11/2 upon exciting the sample with 400nm wavelength. Polarized absorption spectra in UV, visible and NIR regions were recorded for two light polarizations (π and σ) relative to the C3 crystal axis.Energy levels scheme of the doping ion has been compiled after a careful analysis of the spectra by reproducing the observed transitions by means of theoretical calculations based on a Hamiltonian including the free-ion and the crystal-field (CF) terms. Free-ion and crystal-field analyses are performed based on a D3 point-group symmetry Hamiltonian. A best fit between theoretical and experimental energy levels is obtained with a root-mean-square (rms) deviation of 16cm−1. The general trend of the crystal-field parameters of rare earth ions in YAB host is confirmed. The calculated NV crystal-field strength parameter presents a linear variation with the rare earth ionic radii and with the 4fn electron number.

Growth and characterization of self-Q-switched Nd:Cr:YVO_4 crystal

A Nd:Cr:YVO4 crystal was grown by the Czochralski method for the first time to our knowledge. Its structure and cell parameter have been studied by X-ray powder diffraction (XRPD) analysis. Polarized absorption spectra were measured at room temperature, which showed that the absorption bands display polarization character and an absorption band of Cr5+ ions at 1110 nm enables the crystal to be a self-Q-switched laser material. We also found that the absorption of Cr5+ ions became much larger and its self-Q-switched laser performance became much better when the Nd:Cr:YVO4 crystal was annealed because the annealing induces more Cr ions to become those with + 5 valence. In the self-Q-switched laser, the maximum output power, shortest pulse width, and largest pulse energy were obtained to be 120 mW, 85.8 ns, and 0.79 μJ, respectively.

A Hybrid Angular/Energy Dispersive Method to Improve Some Characteristics of Laboratory X-Ray Diffraction

The Energy Dispersive X-ray Diffraction, generally referred as EDXD, has shown to be a valid alternative to the conventional Angular Dispersive X-ray Diffraction, the ADXD. EDXD exhibits several advantages to its AD counterpart, mainly related to the properties of the polychromatic X-ray beam utilized for diffracting, such as higher signal intensities, a wider accessible region of the reciprocal space, a greater transparency of samples, and a parallel data collection of the q-points in the diffraction pattern acquisition. However, the main drawback of poly-chromaticity lays in the fact that the quantities that modulate the scattered intensity in a diffraction measurement depend on the energy. These quantities are the primary X-ray beam spectrum, polarization, and X-ray absorption, the last producing by far the most critical effect because it rapidly changes as a function of energy. Therefore, a detailed knowledge of the energy dependence of all these quantities is required in EDXD in order to process the data correctly and prevent systematic errors. The difficulty in handling the energy-dependent factors complicates the experimental procedure and may make the measurements unreliable. In the present paper, a hybrid method between the ED and AD X-ray Diffraction is proposed to maintain the advantages of the polychromatic nature of the radiation utilized in EDXD, while preventing the problems produced by the energy-dependent quantities.