Transition frequencies and strengths of H217O and H218O: 6600 to 7640 cm(-1)

High-resolution spectra of O(17)- and O(18)-enriched water-vapor samples have been recorded with a Fourier transform spectrometer covering the region between 6600 and 7640 cmcm(-1). Experimental values of line positions and strengths of 1807 absorptions in the (120)-(000), (021)-(000), (200)-(000), (101)-(000), (002)-(000), bands of the two isotopic species were derived from the spectra. The analysis included the determination of accurate rotational levels belonging to the (120), (021), (200), (101), and (002) vibrational states of H(2)(17)O and H(2)(18)O.     

Shock-tube study of high-pressure H2O spectroscopy

Water-vapor absorption features near 7117, 7185, and 7462 cm(-1) were probed at pressures to 65 atm (1 atm = 760 Torr) and temperatures to 1800 K in shock-heated mixtures of H(2)O in N(2) and Ar with a diode-laser source. Calculated absorbances based on Voigt line shapes and measured line parameters were in good agreement, within 10%, with measured absorbances at 7185.4 and 7117.4 cm(-1). We obtained temperature-dependent N(2) and Ar shift parameters for H(2)O absorption features by shifting the calculated spectra to match the recorded absorption scan. Absorbance simulations based on line parameters from HITRAN and HITEMP were found to be similar over the range of temperatures 600-1800 K and were within 25% of the measurements. The combined use of Toth's [Appl. Opt. 36, 4851 (1994)] line positions and strengths and HITRAN broadening parameters resulted in calculated absorption coefficients that were within 15% of the measurements at all three probed wavelengths.     

Single diode laser sensor for wide-range H2O temperature measurements

A single diode laser absorption sensor (near 1477 nm) useful for simultaneous temperature and H2O concentration measurements is developed. The diode laser tunes approximately 1.2 cm(-1) over three H2O absorption transitions in each measurement. The line strengths of the transitions are measured over a temperature range from 468 to 977 K, based on high-resolution absorption measurements in a heated static cell. The results indicate that the selected transitions are suitable for sensitive temperature measurements in atmospheric pressure combustion systems using absorption line ratios. Comparing the results with HITRAN 96 data, it appears that these transitions will be sensitive over a wide range of temperatures (450-2000 K), suggesting applicability for combustion measurements.     

Detection of high-temperature water vapor at 940 nm with vertical-cavity surface-emitting lasers

A vertical-cavity surface-emitting laser was used to study the absorption of water vapor in the 940 nm region. Measurements for several absorption lines within the 2 v1 + V3 vibrational band were performed. Line strengths at room temperature and in a heated absorption cell over the temperature range of 420-970 K were obtained. The line strength values were in good agreement with simulations based on the values of the HITRAN 2004 database. The measurements also showed that water vapor transitions near 940 nm are suitable for sensitive temperature determination.     

Determination of line strengths by Fourier-transform spectroscopy

A rigorous test of the photometric accuracy of commercial high-resolution Fourier transform spectrometers has been made by measuring line strengths in the pure rotational spectrum of carbon monoxide. Measurements have been made with a Bruker IPS 120 HR spectrometer (transitions: J″ = 7 . . . 23) and a Bomen DA3.002 spectrometer (J″ = 27 . . . 35). A least-squares fit of individual data sets and the combined data gave permanent electric dipole moments in the range 0.1091-0.1101 D and quadratic Herman-Wallis factors in the range -0.188 to -0.229 × 10(-3), in good agreement with literature values within the overall uncertainty. Sources of systematic errors in the Fourier-transform spectrometer and in the algorithms used to reduce the data are discussed in detail. The experimental results show that such errors affected the retrieved line strengths by less than 1%.     

Absorption line shift with temperature and pressure: impact on laser-diode-based H2O sensing at 1.393 microm

High-resolution absorption measurements of the H2O line in the v1 + v3 band at 1.3928 microm were made in the temperature range of 296-1100 K by use of an InGaAsP distributed-feedback laser diode operating at 1.39 microm. Spectral line shift, line strength, and N2 broadening on the water-vapor line and their impact on the accuracy of optical-absorption-based gas sensing have been investigated. The results obtained were compared with values obtained from the HITRAN database and values reported in the literature, facilitating H2O sensing in a nonstandard temperature and pressure environment.     

Effect of thermal annealing on the microstructure and morphology of erbium films

The effects of thermal annealing on the microstructure and morphology of erbium films were investigated by X-ray diffraction and scanning electron microscopy. All the erbium films were fabricated by electron-beam vapor deposition. The columnar grain sizes of as-received erbium films increased with the substrate temperatures and were enlarged by the coalescence and migration of grains during the high temperature annealing. The intrinsic stresses of erbium films, fabricated at a low substrate temperature (200 °C), were relaxed accompanied with the appearance of cracks on the films surface. The films deposited at 200 °C had (002) preferred orientation, and the film deposited at 450 °C had mixed (100) and (101) texture. The peak positions and the full width at half maximum of (100), (002), and (101) diffraction lines of erbium shift towards higher angles and sharply decrease during the annealing process, indicating that the stress inside the film was relaxed.     

Optical properties of indium phosphide in the 50-200 Å wavelength region using a reflectivity technique

The optical constants of indium phosphide (InP) in the soft x-ray region of 50-200 ? are determined from angle-dependent reflectivity measurements. The measurements are carried out using the reflectivity beam line at the Indus-1 synchrotron source. The derived optical constants are compared with tabulated values of Henke et al. [At. Data Nucl. Data Tables 54, 181 (1993)]. Experimental values of δ and β are in close agreement with the tabulated values in the lower wavelength region of 50-120 ?. The experimental value indicates an edge shift of 0.4 ? toward the lower wavelength side from the phosphorous L-edge value of 92 ?. However, above the 120 ? region, where the indium N(2) edge falls at 160.7 ?, there is a huge difference between experimental and tabulated values. Both delta and beta values are significantly higher. In contrast to tabulated values of the β/δ ratio, which is more than 1 above the 140 ? region, the experimental measured ratio is found to be less than 1. This study presents the first reported experimental values of optical constants for InP in this wavelength range, to the best of our knowledge.     

Preferred orientation in Ru nanocolumns induced by residual oxygen

Ru nanocolumns were grown on a native oxide covered Si(100) substrate using an oblique angle sputter deposition technique with substrate rotation at room temperature. Scanning tunneling microscopy images of conventional Ru film show the presence of straight columnar features on the film surface, which are very different from the nearly circular features observed on the nanocolumns surface. X-ray diffraction spectra confirm that these nanocolumns have (100) as the preferred orientation instead of the (002) orientation observed for a conventional film. The oxygen to Ru atomic ratio was determined for both the nanocolumns and the conventional film by using X-ray photoelectron spectroscopy. The nanocolumns were observed to incorporate about 6 times more oxygen than the conventional film near the surface region. We argue that the oxygen segregates onto the high-density (002) plane whereas it permeates through comparatively open planes like (100) and (101). The adsorbed oxygen atoms serve as a diffusion barrier for the landing Ru adatoms and inhibit the growth of the (002) plane. This results in the absence of the (002) plane and development of (100) and (101) planes in the nanocolumns. The oxygen plays a decisive role in determining the crystallographic orientation and the feature size/shape over the nanocolumns and conventional film surfaces.     

X-ray topographic study of solid-state polymerized poly-[1,2-bis-(p tolylsulphonyloxymethylene)-1-butene-3-inylene]

Local extinction contrast effects have been observed in macroscopic polymer crystals, using Berg-Barrett X-ray topography. Results from as-polymerized crystals indicate that the crystals are perfect enough for defect regions to be imaged. As-polymerized crystals exhibited apparent defects lying along [021]. [010] slip traces in the (100) surface of a crystal were imaged; the slip system here appears to be consistent with (h01) [¯10h], forh, l 0 and [010] the chain direction.     

Large-scale synthesis of CuS hexaplates in mixed solvents using a solvothermal method

Large-scale covellite CuS hexaplates were successfully synthesized by the 200 °C solvothermal reactions of CuCl₂.2H₂O and (NH₄)₂S in C₂H₅OH-H₂O mixed solvents containing HCOOH as a pH stabilizer, including different amounts and molecular weights (MWs) of polyethylene glycol (PEG). By using XRD and SAED, CuS (hcp) was detected. XRD peaks of the product, synthesized in a solution containing 5 g PEG6000 and 1.5 ml HCOOH for 5 h, are in accordance with those of the simulation and database. The (110) peak shows the preferential growth, corresponding to the hexaplates, characterized using SEM, TEM and HRTEM. CuS hexaplates with the (100) and (010) lattice planes at an angle of 120° were detected on the flat surface, and the (002) lattice plane on the edge. UV-vis absorption edge was detected at 610 nm (2.03 eV), and the PL emission at 361 nm (3.43 eV). Phase and morphology formations were also explained according to the experimental results.     

Diode laser sensor for measurements of CO, CO(2), and CH(4) in combustion flows

A diode laser sensor has been applied to monitor CO, CO(2), and CH(4) in combustion gases with absorption spectroscopy and fast extraction-sampling techniques. Survey spectra of the CO 3nu band (R branch) and the 2nu(1) + 2nu(2)(0) + nu(3) CO(2) band (R branch) near 6350 cm(-1) and H(2)O lines from the nu(1) + 2nu(2) and 2nu(2) + nu(3) bands in the spectral region from 6345 to 6660 cm(-1) were recorded and compared with calculated spectra (from the HITRAN 96 database) to select optimum transitions for species detection. Species concentrations above a laminar, premixed, methane-air flame were determined from measured absorption in a fast-flow multipass absorption cell containing probe-sampled combustion gases; good agreement was found with calculated chemical equilibrium values.     

Intracavity absorption spectroscopy with a tunable multimode traveling-wave ring Ti:sapphire laser

A tunable multimode unidirectional traveling-wave Ti:sapphire laser was developed to measure in situ the atmospheric absorption spectra using intracavity absorption spectroscopy. The effective absorption path length was 2100 km. O2 and H2O vapor lines in atmosphere with absorption coefficients of 10(-6)-10(-8) cm(-1) were measured with uncertainties <5%, and the absorption coefficients were in agreement with those estimated from the HITRAN database. By tuning the wavelength, a weak absorption line with an absorption coefficient of 10(-9) cm(-1) was measured with a sensitivity of 2×10(-10) cm(-1). The sensitivity was limited by the residual parasitic variation that appeared in the spectrum.     

Twinning and orientation relationships of T-phase precipitates in an Al matrix

The recent increasing interest of T-phase in Al alloy has been switched to its twins. In this study, we employed high resolution transmission electron microscopy to study and compare the morphology and orientation relationships (OR) of T-phase and its twins in an Al–Cu–Mg–Mn alloy. It is found that T-phase tends to form on the {403}_Al habit planes and exhibit a rod-like shape, with it longitudinal axis, [010]_T, being parallel to the matrix [010]_Al direction. Three different OR types are determined between T-phase and Al matrix, namely, {200}_T〈010〉_T//{200}_Al〈010〉_Al (OR-I), {200}_T〈010〉_T// $ \{ 40\bar{3}\}_{\text{Al}} $ 〈010〉_Al (OR-II), and {200}_T〈010〉_T//{301}_Al〈010〉_Al (OR-III). OR-II is the most widely observed OR, while OR-I and III can form from the OR-II by twinning. During the twinning, the cross-section of T-phase transforms from a parallelogram-like shape into a shell-like shape. Further analyses on the shell-like T-twins strongly suggest that tenfold twins could form directly from the successive twinning of an individual T crystal.     

AFGL atmospheric absorption line parameters compilation: 1982 edition

The latest edition of the AFGL atmospheric absorption line parameters compilation for the seven most active infrared terrestrial absorbers is described. Major modifications to the atlas for this edition include updating of water-vapor parameters from 0 to 4300 cm(-1), improvements to line positions for carbon dioxide, substantial modifications to the ozone bands in the middle to far infrared, and improvements to the 7- and 2.3-microm bands of methane. The atlas now contains approximately 181,000 rotation and vibration-rotation transitions between 0 and 17,900 cm(-1). The sources of the absorption parameters are summarized.     

Structural and optical properties of tin oxide branched nanostructures

Branched nanostructures of tin oxide (SnO2) have been synthesized by Vapor-Liquid-Solid (VLS) mechanism using a gold catalyst in the temperature range of 800-850 degrees C under an ambient gas flow of 200 sccm. The microstructural and the optical properties of the as prepared products have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro-Raman, and photoluminescence (PL) studies. SnO2 branches with a rutile phase are found to have a preferential orientation along (101). Typical lengths of these branches are found to be approximately 3-5 microm and diameters in the range of 50-100 nm. Selected area electron diffraction (SAED) pattern shows that the SnO2 branches have a tetragonal cross section with [101] crystal direction. A Raman line at 631 cm(-1) (Sn-O bond) is obtained in the micro Raman spectra. Low temperature PL spectrum shows a strong green emission band near 506 nm.     

Algorithm for the retrieval of columnar water vapor from hyperspectral remotely sensed data

A new algorithm for the retrieval of columnar water vapor content is presented. The proposed procedure computes the area of the H2O absorption centered about 940 nm to allow its integrated columnar abundance as well as its density at ground level to be assessed. The procedure utilizes the HITRAN 2000 database as the source of H2O cross-section spectra. Experimental results were derived from radiometrically calibrated hyperspectral images collected by the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) sensor over the Cuprite mining district in Nevada. Numerical simulations based on the MODTRAN 4 radiative transfer code were also employed for investigating the algorithm's performance. An additional empirical H2O retrieval procedure was tested by use of data gathered by the VIRS-200 imaging spectrometer.     

Ultraviolet antireflection coatings for use in silicon detector design

We report on the development of coatings for a charged-coupled device (CCD) detector optimized for use in a fixed dispersion UV spectrograph. Because of the rapidly changing index of refraction of Si, single layer broadband antireflection (AR) coatings are not suitable to increase quantum efficiency at all wavelengths of interest. Instead, we describe a creative solution that provides excellent performance over UV wavelengths. We describe progress in the development of a coated CCD detector with theoretical quantum efficiencies (QEs) of greater than 60% at wavelengths from 120 to 300 nm. This high efficiency may be reached by coating a backside-illuminated, thinned, delta-doped CCD with a series of thin film AR coatings. The materials tested include MgF(2) (optimized for highest performance from 120-150 nm), SiO(2) (150-180 nm), Al(2)O(3) (180-240 nm), MgO (200-250 nm), and HfO(2) (240-300 nm). A variety of deposition techniques were tested and a selection of coatings that minimized reflectance on a Si test wafer were applied to functional devices. We also discuss future uses and improvements, including graded and multilayer coatings.     

凝胶注模常温发泡制备氧化铝多孔陶瓷

以高纯氧化铝为原料,通过起泡结合凝胶注模成型的方法制备了孔隙率为77%～85%、孔径为40～200μm的氧化铝多孔陶瓷.多孔陶瓷组成为α-Al2O3.多孔陶瓷的微结构可通过固含量与发泡剂加入量的改变进行调控.多孔陶瓷的耐压强度为9.40～32.50MPa,且对其断裂方式进行了研究.多孔陶瓷在1000℃下的热导率为0.80 W.(m.K)-1.