Thermal Emission Spectroscopy Research Articles

Near-IR Spectroscopy of the Atmosphere of Jupiter

AbstractThe Galileo Near Infrared Mapping Spectrometer (NIMS) obtains spectral images in the wavelength range 0.7 to 5.2 μm with a spectral resolving power of approximately 200. This spectral range allows NIMS to sense cloud-reflected solar radiation, thermal emission produced in the deep atmosphere, and auroral emission from the thermosphere of Jupiter. Using 5 μm thermal emission spectroscopy, the amount of water vapor in the deep atmosphere, at approximately the (i to 8 bar level, is found to vary by a factor > 100. Deep atmosphere ammonia was also found to vary, with a spatial behavior different from that of water vapor. No evidence is found for a massive water cloud. Using reflected solar radiation in conjunction with thermal emission, two cloud layers are found, the upper at 0.5 bars and a lower one at 1-1.3 bars. The inferred absorption properties of these clouds are consistent with ammonia crystals (the upper cloud) and ammonium hydrosulfide particles (the lower cloud).

Differential thermal analysis of the mixtures of silicon and red lead

There are two different opinions in the literature on the combustion mechanism of the Si-Pb3O4 system. Differential thermal analysis, X-ray diffraction and infra-red spectroscopy have been used to examine the thermal behaviour of the mixture to characterize its combustion products and judge the validity of both proposed reaction paths.

Quantitative thermal emission spectroscopy of minerals: A laboratory technique for measurement and calibration

Previous descriptions of thermal emission spectroscopy have presented techniques that vary in accuracy and reproducibility. Contributions of thermal energy from the instrument and environment are major calibration factors that limit accuracy in emissivity determination. Reproducibility is related to the stability of these quantities. Sample temperature determination is also a significant factor in arriving at accurate emissivity. All of the factors which impact the measurement of emissivity using an interferometric spectrometer with an uncooled detector are isolated and examined here. An experimental apparatus is presented along with a description of a simplified measurement and calibration scheme used to arrive at quantitative emissivity of minerals. A detailed error analysis examines the effect of errors in each of the calibration parameters in isolation and as part of multiple error propagation. Sample temperature determination from radiance can create emissivity error, but 95% of published minerals have an emissivity maximum of 0.98 or higher, resulting in emissivity error of 2% or less. With worst‐case systematic and random errors included, emissivity can be determined with an uncertainty of ∼4%. In most cases it is less than 2%. Reproducibility with this technique is better than 1%.

Synthesis of spodumene and spodumene — zirconia composite powders using aqueous sol-gel method

Pure spodumene and spodumene-zirconia (5, 10, 15 mol%) composite powders were prepared using aqueous sol-gel method employing lithium formate, aluminium formate, zirconium formate and tetraethoxy silane (TEOS) as starting materials in aqueous medium. The gels prepared by this method were dried at 100°C for 24h and then calcined for 2h at different temperatures ranging from 500°C to 800°C. X-ray powder diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and infra-red spectroscopy analysis (IR) were utilized to characterize the gel powders and calcined powders. Transmission electron microscope (TEM) was used to measure the average particle size of the calcined powders.

Structure investigations of a crosslinkable main chain liquid crystalline copolyester by infrared spectroscopy, differential scanning calorimetry and wide‐angle X‐ray scattering

AbstractFTIR spectroscopy, differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS) were used for the characterization of structural properties of a cross‐linkable ternary liquid crystalline (lc) copolyester and its binary model copolyesters. The copolyesters based on itaconoylbis(4‐oxybenzoic acid), sebacoylbis(4‐oxybenzoic acid) and 2‐methylhydroquinone were annealed at different temperatures to analyse the structural changes of mesogenic and spacer segments due to their phase transitions. The results of the DSC and WAXS measurements are useful to explain the small effects in the IR spectra connected with polymer morphology. FTIR spectroscopy is able to provide information about the molecular structure along the polymer chains and also about the interactions between these chains. Micro‐ and macromolecular structures influence the orientation and crosslinking processes in dependence on temperature and time. It was shown that an increase in the ordered state and quality of crystallinity was obtained using different annealing procedures.

Measurement of tropospheric ozone by thermal emission spectroscopy

A new technique has been developed for the remote sensing of tropospheric ozone. In this technique the thermal radiation from ozone is measured against the cold background blackbody emission of clouds using ground-based FTIR spectroscopy. Preliminary measurements obtained in the springtime at Peterborough, Ontario, using this new technique, have indicated an average tropospheric ozone mixing ratio of 50 ± 7 ppbv within a 2.7 km layer from the surface for air flowing from a heavily industrialized and highly urbanized region. Ozone concentrations of this magnitude are in accordance with the amounts obtained for moderately polluted, springtime air using traditional in situ measurement techniques. The greenhouse radiation flux associated with this amount of ozone was estimated to be 0.61 W m −2 ± 13%. Since there are few techniques available for the remote sensing of tropospheric air pollutants, this new technique could be a potentially valuable development.

Synthesis and phase transformations of mullites obtained from SiO 2Al 2O 3 gels

Synthesis and structural characterization of mullite phases obtained from three nominal compositions in the SiO 2Al 2O 3 system is reported and comparisons between them are established. Monosized gels with Al Si atomic ratios of 2:3, 3:1 and 9:1 were obtained and thermally treated at temperatures between 700 and 1500 °C. The thermal evolution of amorphous gels was followed by thermal analysis, X-ray diffraction and infra-red spectroscopy. The microstructural changes were studied by scanning electron microscopy and transmission electron microscopy. The formation of Al 2O 3-rich mullite started around 1000 °C for all samples and was fully developed at 1400 °C. The chemical composition of mullites changed as a function of calcining temperature. An anomalous low value of the lattice parameter a was obtained for the sample with Al Si atomic ratio of 9:1 compared with the 3:1 sample at 1400 °C, which may be due to the slow reaction rate of Al 2O 3 with SiO 2-rich glassy phase during mullite formation.

Some peculiarities of oxidative dehydrogenation of TiH 2 as a component of bioradioprotective composites

An analytical expression of the relationship between activation energy, temperature change rate and peak temperature of thermal plots has been obtained. By complex thermal analysis and X-ray emission spectroscopy it was found that titanium dihydride, obtained with self-developed high temperature synthesis (SDHTS), was chemico-physically defected (heterogeneous product) having free metal, which during heating led to an exothermic reaction of oxidative cross-hydrogenation. A possibility of synthesis of TiH x with x > 2 has been demonstrated. A structure and composition of the condensed phase TiH X ( x > 2) with maximal atomic ratio H:Ti was proposed. TiO 2 as a final product of oxidative dehydrogenation has been found to destabilize the TiH 2. Stabilizing dopants increased the peak temperatures of thermal plots in the 10–50 K temperature range and gave thermostable TiH 2. The stabilized TiH 2 is promising as a component (base) of effective bioprotective composites.

FTIR spectra of deoxyoligonucleotide‐nogalamycin complexes

AbstractFTIR spectroscopy has been used to study the three self‐complementary oligonucleotides TGATCA, CGATCG, and TGTACA in the form of complexes with the anthracycline drug nogalamycin. These complexes were prepared under conditions that enable the bulky nogalamycin to intercalate into the double helixes of the oligonucleotide duplexes. Changes in the FTIR spectra on complexation are indicative of strong perturbation of the AT base pairs, in contrast with the effect of the structurally related drugs adriamycin and daunamycin, which show affinity for GC base pairs. These differences are attributed to binding interactions with the functional groups attached to the aglycone chromophore rather than to the specific site of drug intercalation in the double helix. © 1995 John Wiley & Sons, Inc.

Structural influence of the carbon chain length in hybrid materials obtained from zirconium n-propoxide and diols

Zirconium n-propoxide Zr(OPr n )4 has been chemically modified by 1,3-propanediol and 1,3-butanediol with molar ratio r=0.5, 1 and 2. The properties of the hybrid organic-inorganic materials obtained after drying at 100°C for 24 hours have been measured by thermal analysis, X-ray diffraction, infra-red spectroscopy and 13C NMR with cross-polarisation at magic angle spinning. Chemical modification of the zirconium precursor at a molecular level has been clearly detected, with a bridging coordination mode for both diols. If the coordination mode of the diols cannot be changed by increasing the carbon chain length, it was found using 13C CP MAS NMR that the local order is much more well-defined when the reactivity of both OH groups are not the same. Thus, using 1,3-butanediol which has a primary and a secondary OH group, it is possible to obtain after complete modification (r=2) a highly homogeneous hybrid polymer which transforms directly into tetragonal zirconia below 400°C. With other diols (1,2-ethanediol and 1,3-propanediol), the hybrid materials transform into tetragonal zirconia above 400°C through a decomposition process involving several steps. Then playing with the carbon chain length and/or the steric hindrance around the OH groups provides an easy way to monitor the ultrastructure of these hybrid materials, and allows a better control of the gel → oxide transformation.

Supramolecular assembly in a polymer/ low-molar-mass system

Thermal analysis and infra-red spectroscopy have been used to study the interactions between poly ( N-vinylpyrrolidone) and low-molar-mass, hydrogen-bonding-active aromatics. A remarkably strong interaction is observed between the polymer and 3,5-dihydroxybenzoic acid, which is consistent with the crosslinking of the polymer by acid dimers.

Chemical change in the Arctic Vortex during AASE II

We measured column abundances of HF, HCl, O3, HNO3, and H2O on the NASA DC‐8 during the AASE II campaign, using thermal emission spectroscopy. We made multiple traversals of the Arctic vortex and surroundings. Using HF as a tracer, we remove the effects of subsidence from the measured column abundances; perturbations in the resulting column abundances are attributed to chemical processing. We find that by January 1992 the stratospheric column in the vortex had been chemically depleted by about (55±10)% in HCl and (35±10)% in O3, and enhanced by about (15±10)% in HNO3 and (0±10)% in H2O.

Synthesis and thermal evolution of structure in alkoxide-derived niobium pentoxide gels

Niobium pentoxide gels in the form of transparent monoliths and powder have been synthesized from the controlled hydrolysis and polycondensation of niobium pentaethoxide under different experimental conditions using various mole ratios of Nb(OC2H5)5:H2O:C2H5OH:HCl. Alcohol acted as the mutual solvent and HCl as the deflocculating agent. In the absence of HCl, precipitation of colloidal particles was encountered on the addition of any water to the alkoxide. The gels were subjected to various thermal treatments and characterized by differential thermal analysis, thermogravimetric analysis, X-ray diffraction and infra-red spectroscopy. After drying at 400°C, the gels were amorphous to X-rays. The amorphous powder crystallized into the low temperature orthorhombic form of Nb2O5 at ~ 500°C, which transformed irreversibly into the high temperature monoclinic α-Nb2O5 between 900 to 1000°C. The kinetics of crystallization of the amorphous niobium pentoxide have been investigated by non-isothermal differential scanning calorimetry. The crystallization activation energy was determined to be 399 kJ mol−1.

Evaluation of infrared emission spectroscopy for mapping the moon's surface composition from lunar orbit

Infrared thermal emission spectroscopy is evaluated for its possible application to compositional mapping of the Moon's surface from lunar orbit. Principles of the mid‐IR (∼4–25 μm) technique, previous lunar ground‐based observations, and laboratory studies of Moon samples are reviewed and summarized. A lunar thermal emission spectrometer experiment is described, patterned after a similar instrument on the Mars Observer spacecraft. Thermal emission spectrometry from a polar‐orbiting lunar spacecraft could provide a valuable mapping tool to aid in exploration for lunar resources and help provide understanding of the origin of the Moon and history of lunar surface processes.

The slip‐reducing mechanism in polypropylene‐laminated films studied by FTIR and XPS

AbstractFTIR spectroscopy and X‐ray photoelectron spectroscopy (XPS) were applied to examine the slip‐reducing mechanism of polypropylene‐laminated films. The relationship between the slip and the amount of lubricants was established on the basis of quantitative analysis of lubricants on the cast and laminated polypropylene film surfaces. The results suggested that erucic amide used as a lubricant for the cast film migrated from the film surface into the adhesive layer, probably due to intermolecular interactions (hydrogen bonds) with an isocyanurate‐ether‐polyol used as an adhesive for laminating the films. This enabled us to understand the slip‐reducing mechanism in the laminated films. © 1993 John Wiley & Sons, Inc.

Application of Ftir Spectroscopy to the Characterization of as-Deposited and Chemical Mechanical Polished (CMP) Electron Cyclotron Resonance (ECR) Plasma Based SiO2 Films

AbstractFTIR spectroscopy has been used to characterize as-deposited and chemical mechanical polished (CMP) electron cyclotron resonance (ECR) plasma based SiOx films. The ECR films were deposited at different O2/SiH4 gas ratios in an attempt to vary the film stochiometry. Transmission and reflectance-absorbance IR spectral data were combined with CMP removal rate information to characterize the SiOx films and their polishing behavior. The asymmetric O-Si-O stretching (ASM) and Si-OH vibrational bands were found to be principal sources of information.

Mars Observer - The next Mars mission

The next mission to Mars, called Mars Observer, will be launched in September 1992. After the capture of the spacecraft by the planet and the adjustment into a low, Sun-synchronous, polar-mapping orbit in late 1993, observations will continue for a Mars year (687 days). The scientific mission centers around global geoscience and climatology observations of the Mars atmosphere, surface, and interior. The seven experiments carried by the spacecraft involve gamma-ray spectroscopy, magnetometry, surface and atmospheric imaging, atmospheric sounding, laser altimetry, gravity mapping, and thermal emission spectroscopy. All experiments contain microprocessors, which will be controlled remotely from the investigator's home institution. The long planned period of continuous 24 hi day observation promises a rich harvest of global and seasonal information. Mars Observer stands between the initial exploration of Mars and the more intensive explorations,. possibly involving human beings, that are only now being planned.

Measurement of the stratospheric hydrogen peroxide concentration profile using far infrared thermal emission spectroscopy

We have made the first unequivocal measurement of hydrogen peroxide in the stratosphere, a concentration profile obtained from a balloon platform using Fourier transform thermal emission spectroscopy in the far infrared. Measurements were made using the 112 cm−1RQ5 branch of the rotational‐torsional spectrum, with some confirmation from the 94 cm−1RQ4 branch. The atmospheric spectra were obtained from a balloon flight on September 26–27, 1989, launched from Fort Sumner, NM.The volume mixing ratio of H2O2 is 1.6 × l0−10 at 38.4 km, decreasing to 0.6 × l0−10 at 23.8km, with uncertainties of about 16% (1σ). Our measurements are compared to a recent stratospheric model calculation.

Infrared reflectance spectra (2.2–15 μm) of plagioclase feldspars

Laboratory results show that (1) the Christiansen frequency (CF) feature in mid‐infrared reflectance spectra of powders can be used to accurately distinguish plagioclase composition, and (2) the wavelength position of the CF is not affected by vitrification of the plagioclase. Although the CF position does not distinguish glass from crystalline forms of plagioclase, other features (combination‐tone, overtone, restrahlen bands) in the mid‐IR spectra of plagioclase can be used for that purpose. These results have important implications for application of thermal emission spectroscopy to mapping the surface composition of regolith‐covered planetary bodies like the Moon, Mars, and asteroids.

Applications of Laser-Induced Thermal Emission Spectroscopy to Various Samples

The Laser-Induced Thermal Emission (LITE) spectra of several solid samples were measured and compared with the usual thermal emission spectra generated by the heating element. The following advantages in LITE spectroscopy were made clear: (1) the spectral background is reduced; (2) the time required for the stabilization of the thermal emission signal is short; (3) the compounds which are coated on background materials with complex shapes can be measured.