Quantitative single point imaging with compressed sensing

A novel approach with respect to single point imaging (SPI), compressed sensing, is presented here that is shown to significantly reduce the loss of accuracy of reconstructed images from under-sampled acquisition data. SPI complements compressed sensing extremely well as it allows unconstrained selection of sampling trajectories. Dynamic processes featuring short NMR signal can thus be more rapidly imaged, in our case the absorption of moisture by a cereal-based wafer material, with minimal loss of image quantification. The absolute moisture content distribution is recovered via a series of images acquired with variable phase encoding times allowing extrapolation to time zero for each image pixel and the effective removal of contrast.     

Continuum radiation spectroscopy in a high-pressure argon-mercury lamp

A primary study of the continuum emission from the arc of a high-intensity discharge (HID) lamp with an argon-mercury chemistry at pressures higher than is reported. Spectrally and spatially resolved calibrated continuum spectra from a vertically mounted test lamp (an MHN150 vessel filled at room temperature with 12 mg mercury and 400 mbar argon) are reported for the visible and infrared wavelength range 0.3-. These spectra were analyzed to quantify the infrared (IR) losses and to determine the temperature profile inside the lamp.     

Infrared radiation of zinc selenide single crystals

Long-wave photoluminescence (PL) spectra of both as-grown and Au-doped n-ZnSe single crystals are studied in the temperature range from 81 to 300 K. A narrow band of infrared (IR) radiation centered at 878 nm (1.411 eV) manifests itself in the low-temperature PL spectrum. It is established that this band intensity first increases and then decreases with increasing concentration of doping impurity. With increasing excitation radiation intensity, spectral position of the IR PL band is unchanged and its intensity increases under the linear law. With increasing excitation radiation wavelength, the IR PL band intensity increases, it becomes narrower and shifts towards long wavelengths. It is shown that the observed IR radiation is caused by recombination of free electrons with holes localized on associative acceptors in the ZnSe:Zn:Au crystals or in the undoped crystals.     

The effect of the Bi source on optical properties of Bi2Te3 nanostructures

nanostructures were synthesized by using different Bi sources via a simple solvothermal process, in which and BiCl₃ were used as the Bi sources. Optical properties of nanostructures prepared with and BiCl₃ as the Bi sources were investigated by micro-Raman spectroscopy. The Raman scattering spectrum of hexagonal nanoplates prepared by using as the Bi source shows that the infrared (IR) active mode A_1u, which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shows up clearly in the Raman scattering spectrum. We attribute the appearance of the infrared active A_1u mode in the Raman spectrum to crystal symmetry breaking of hexagonal nanoplates. However, the Raman scattering spectrum of nanostructures with irregular shape prepared by using as the Bi source only exhibits the two characteristic Raman modes of crystals. Micro-Raman measurements on nanostructures with different morphologies offer us a potential way to tailor optical properties of nanostructures by controlling the morphologies of the nanostructures, which is very important for practical applications of nanostructures in thermoelectric devices.     

Modeling, measuring, and minimizing the instrument response function of a tunable diode laser spectrometer

The instrument response function (IRF) of a spectrometer limits the accuracy of measured spectroscopic parameters by broadening recorded spectral lines/features. We describe methods to model the effects of the IRF on spectral data, to minimize the IRF widths, and to measure the resulting width of the spectrometer IRF. We have modeled the IRF of our Tunable Diode Laser Spectrometer as a Voigt function. A real-time method of eliminating the effects of low-frequency spectrometer drift has been implemented and has resulted in a substantial reduction in the width of the IRF, its residual Gaussian component reduced from about to about . An accurate measurement of the IRF Gaussian width utilizes a computationally simple method making use of the spectral dependence of the RMS noise of each signal-averaged data point. Various noise sources affecting the spectrometer (preamp/detector noise, laser AM noise, and laser FM noise) are identified and separately quantified by use of the same method. The IRF Gaussian-width measurement can be automatically applied to each measured spectrum of an experimental data set. A related method is discussed which allows accurate determination of the spectral dependence of statistical noise appropriate for use in quantitative Chi-square fitting of absorption spectra. We explore simple, efficient numerical processes which can dramatically enhance the quality and usefulness of acquired spectral data, improving the ability to apply TDL spectroscopy to high-precision, quantitative measurements and the determination of detailed spectroscopic lineshape parameters. This paper provides a guide for interested readers to implement these developments in their own spectrometers.     

Sleep disturbance by traffic noise: an experimental study in subjects' own houses using a portable CD player

The current study investigated the effect of noise on sleep in subjects' own houses using recorded traffic noises. A railway noise and two kinds of road traffic noise differing in level-fluctuations were used as stimuli. Subjects were exposed all night to the artificially controlled stimuli for 10 days through a portable compact disc (CD) player. The effect of noise on sleep was judged in three ways, namely whether the subject had switched off the CD player, a self-declaration of the subject based on a questionnaire, and the amount of arm movement of the subject during the night as measured by an actigraph. The results of the analysis of the self-declaration data showed that the thresholds where sleep disturbance began were 40-45 dB in for road traffic noise and about 35 dB for railway noise, which corresponded to 50-55 dB in L_A,Fmax of each train noise event. The results of the analysis of the actigraphy data showed a rapid increase in the incidence of mid-sleep awakening at sound pressure levels higher than 50 dB, for railway noise. However, neither of the road traffic noises showed such a tendency, as long as the sound pressure level was less than 55 dB, .     

Observation of room temperature photoluminescence in proton irradiated SrTiO3 single crystal

We have irradiated SrTiO₃ single crystal with 3 MeV-proton (H⁺) beam and found that blue -, green - and infrared - frequency photoluminescence (PL) are induced simultaneously at room temperature. TEM and EELS analyses show that an oxygen-deficient amorphous layer is formed at the crystal surface by the proton irradiation. Possible origin of the PL-effect is discussed.     

一种基于时域滤波的红外序列图像去噪算法

红外图像是现代光学设备常用的图像源,图像显示效果直接影响设备的用户体验,而红外序列图像中的噪声会导致显示效果的下降。为了减轻噪声对红外序列图像显示效果的影响,通过历史多帧灰度值的加权和当前帧无噪声图像的估计,提出了一种基于时域高斯滤波的去噪方法。参考空域双边滤波的权值分配方法,引入了灰度值的影响对时域高斯滤波的权值进行修正,解决时域滤波导致的序列图像中运动目标拖尾和模糊。实验结果表明,时域滤波方法能够有效平滑帧间噪声,减轻噪声导致的红外序列图像显示效果的恶化,引入灰度值的影响进行滤波权值修正之后,能够解决时域滤波导致的运动目标拖尾和模糊问题。     

The program complex for computation of spectroscopic characteristics of atomic and molecular gases in UV, visible and IR spectral ranges for a wide range of temperatures and pressures

The program complex intended for calculations, on the personal computer, of spectroscopic properties of separate gases and their mixes in UV, visible and IR ranges is submitted in this work. It consists of algorithms describing spectroscopic characteristics of the neutral and ionized atoms and molecules; banks of initial data, physical, thermodynamic and spectroscopic constants, parameters and package of applied programs.The complex allows the computation of parameters of fine and hyperfine structure in electronic-vibrational-rotational spectrums of diatomic molecules, such as wave numbers, Hönl-London factors, intensities and half-widths of rotational lines; absorption coefficients, absorption cross-sections and emissivity of the heated-up gases with the account of Λ-doubling in ranges of temperatures 200-, pressure 10⁻⁵- and wavelengths 0.1- at anyone spectral intervals of averaging.     

Temperature-dependent absorption cross-sections of HCFC-142b

Following the recent detection of HCFC-142b (1-chloro-1,1-difluoroethane) from space, laboratory infrared absorption cross-section spectra of this molecule in a pure vapour phase have been recorded in the spectral region using Fourier transform spectroscopy. The spectra have been recorded at a resolution of and a range of temperatures from 223 to 283 K. The resulting data show good agreement with the harmonic frequencies and intensities calculated using density functional theory as well as with the integrated absorption intensities of the spectral bands available in the literature. The new cross-sections will allow more accurate retrieval of atmospheric HCFC-142b concentrations using infrared spectroscopic techniques.     

Optical phonon modes and structure of ZnGa2Se4 and ZnGa2S4

We present the infrared and Raman study of the optical phonon modes of the defective compounds ZnGa₂Se₄ and ZnGa₂S₄. Most of the compounds have been found to crystallize in the thiogallate structure (defect chalcopyrite) with space group where all cations and vacancies are ordered. For some Zinc compounds a partially disordered cationic sublattice with various degrees of cation and vacancy statistical distribution, which lead to the higher symmetry (defect stannite), has been reported. For ZnGa₂Se₄ we have found three modes of A symmetry, showing Raman activity only. In addition, we have observed each five modes of B and E symmetry, showing infrared as well as Raman activity. The number of modes and their symmetry assignment, based on polarized measurements, clearly indicate space group for the investigated crystals of ZnGa₂Se₄.Regarding ZnGa₂S₄ we have found three modes exclusively showing Raman activity (2A⊕1B₁), and only eight modes showing infrared as well as Raman activity (3B₂⊕5E). The assignment of the modes has been derived by analyzing the spectral positions of the vibrational modes in comparison to a number of compounds. From the number and symmetry assignment of the optical phonon modes we confirm that ZnGa₂S₄ most likely crystallizes in space group .     

Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction (), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8-10 mJ/m² for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same . No electron acceptor interaction is found on the surfaces.The of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between and dielectric constant or dipole moment of the polar probe liquids. The changes in of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.     

Investigation of the water-vapor continuum in the THz region using a multipass cell

Laboratory absorption measurements of the water-vapor continuum in the far infrared region from 12 to (0.4 - 1.83 THz) were obtained using a multipass absorption cell, a Fourier transform spectrometer and a liquid-He-cooled bolometer detector. Measurements were made at a temperature, with water vapor and nitrogen pressures up to 2.2 and , respectively. The effects of the choice of lineshape function and far-wing cut-off factors on the reported continuum absorption are analyzed by modeling the resonant water-vapor spectrum using van Vleck-Weisskopf and Lorentzian lineshapes. Comparisons with available microwave data and model calculations are also presented.