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  • SAGE Publications  (9)
  • Chemistry/Pharmacy  (9)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 1982
    In:  Applied Spectroscopy Vol. 36, No. 6 ( 1982-11), p. 637-643
    In: Applied Spectroscopy, SAGE Publications, Vol. 36, No. 6 ( 1982-11), p. 637-643
    Abstract: The effects of the air-acetylene ratio and the observation height on the detection limits and analytical accuracy of 11 elements (Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn) determined by simultaneous multielement atomic absorption spectrometry with a continuum source (SIMAAC) were investigated. Determinations were made at four observation heights and five airacetylene ratios evenly spaced over normal ranges for these variables. For the 11 elements, detection limits and characteristic concentrations varied by factors of 1.5 to 25. The best compromise detection limits were obtained at observation heights low in the flame and with richer flames. The variations of the analytical recoveries for Co, Cr, Cu, Fe, K, Mg, Na, and Zn determined in a National Bureau of Standards (NBS) standard reference material (SRM) and two United States Geological Survey (USGS) standard rocks as a function of the flame parameters were relatively insignificant. Significant variations were observed for Ca and Mg, whereas the concentration of Ni was too low to permit any conclusions. The optimal, compromise flame parameters, for analytical accuracy, were the two lowest observation heights in lean flames when all elements except Ca and Mg were determined. Inclusion of Mg shifted the optimal parameters to a higher observation height. Four NBS SRM's and three USGS standard rocks were analyzed weekly, over a 7-week period, at a low observation height in a lean air-acetylene flame. In general, accuracies within ±5% of 100% and precisions of ±5% were obtained for Co, Cr, Cu, Fe, K, Mn, Na, and Zn. Acceptable recovery (100% ± 5%) for Ca could only be obtained with a large dilution of the sample into a 0.5% La matrix.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1982
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 2
    In: Applied Spectroscopy, SAGE Publications, Vol. 44, No. 7 ( 1990-08), p. 1137-1142
    Abstract: It has been shown that the use of a polarized attenuated total reflectance (ATR) infrared technique affords a means to study structure/frequency relationships and orientational behavior in partially oriented nylon (PON) yarns. In continuing studies, efforts have been directed toward the study of orientational development in the high-speed spinning of high-viscosity (HV) and low-viscosity (LV) Nylon 66 yarns. Infrared dichroism was used to study fiber orientation, and a relationship between infrared dichroism and orientation factor has been developed. The relationship between orientation measured by infrared and by x-ray diffraction is also shown. These are used to obtain the transition moment direction of a molecular vibration, which would otherwise be impossible to obtain by a single technique. Transition moment angles determined for crystalline vibrations were 39° and 41° with respect to the molecular chain axis for high- and low-viscosity PONs, respectively. Crystalline orientation factors obtained with these values are in excellent agreement with x-ray results. Infrared data indicate a sharp increase in crystalline orientation at slower spinning speeds up to a point (transition point); then orientation increases monotonically with increasing speeds. Beyond the transition point, high-viscosity yarn showed less orientation; below this point it showed higher orientation than lower-viscosity yarn. This transition is interpreted to be related to the molecular relaxation phenomenon. Amorphous orientation was also estimated from the f IR and birefringence data, following the relationship proposed by Samuels. It was found that amorphous orientation was less than crystalline orientation at all speeds and practically insignificant at slower speeds, which leads us to the conclusion that, at low-to-moderate spinning speed, crystalline orientation predominates.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1990
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 1990
    In:  Applied Spectroscopy Vol. 44, No. 2 ( 1990-02), p. 286-289
    In: Applied Spectroscopy, SAGE Publications, Vol. 44, No. 2 ( 1990-02), p. 286-289
    Abstract: Attenuated total reflection (ATR) spectroscopy has been shown to eliminate many of the difficulties encountered in the past with the sample presentation for infrared analysis. Yarn orientation behavior at different draw ratios was studied by analysis of polarized infrared spectra. The data demonstrate that the α conformation increases with drawing for nylon 6,6 fibers. The chain conformation and crystallite orientation which occur during drawing of nylon 6,6 fibers are also demonstrated. The structural changes observed by the present technique seem to agree well with x-ray diffraction data.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1990
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 1984
    In:  Applied Spectroscopy Vol. 38, No. 5 ( 1984-09), p. 680-686
    In: Applied Spectroscopy, SAGE Publications, Vol. 38, No. 5 ( 1984-09), p. 680-686
    Abstract: A Fourier transform infrared microspectroscopic method has been developed for obtaining kinetic data as a function of pressure and temperature The method employs a diamond-anvil high-pressure cell with heating capability, in conjunction with an FT-IR spectrometer modified with an on-axis cassegrain-type beam condenser Time-dependent absorption spectra have been obtained for the thermal decomposition of 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) as a function of pressure and temperature The pressure dependence of the temperature of thermal decomposition has also been determined The method has wide applicability to kinetic measurements in general
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1984
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 1985
    In:  Applied Spectroscopy Vol. 39, No. 1 ( 1985-01), p. 1-5
    In: Applied Spectroscopy, SAGE Publications, Vol. 39, No. 1 ( 1985-01), p. 1-5
    Abstract: The efficiency of an echelle grating spectrometer incorporating prism cross-dispersion is empirically evaluated over a broad wavelength range incorporating a large number of orders. A derived parameter, the spectrometer efficiency, proportional to the spectrometer luminosity, conveniently gauges dynamic features of the echelle efficiency. Characteristics of efficiency over broad wavelengths suggested by earlier work are clearly observed. The shift of blaze wavelength with decreasing order of diffraction, predicted in a recent model of echelle grating efficiency, is experimentally documented.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1985
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 1990
    In:  Applied Spectroscopy Vol. 44, No. 8 ( 1990-09), p. 1297-1300
    In: Applied Spectroscopy, SAGE Publications, Vol. 44, No. 8 ( 1990-09), p. 1297-1300
    Abstract: Near-infrared-FT-Raman spectroscopy can be used to nondestructively analyze reaction-injection-molded (RIM) Polyurethane elastomers. Unlike conventional 514.5-nm excitation, the 1064.1-nm excitation of NIR-FT-Raman spectroscopy does not produce significant sample fluorescence. In this work, the ability of NIR-FT-Raman spectroscopy to determine flex moduli of Polyurethane elastomers is evaluated. Comparisons are made between NIR-FT-Raman, dispersive Raman with 514.5-nm and 752-nm excitation, and NIR diffuse reflectance spectroscopy for Polyurethane analysis.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1990
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 7
    Online Resource
    Online Resource
    SAGE Publications ; 2001
    In:  Applied Spectroscopy Vol. 55, No. 2 ( 2001-02), p. 125-129
    In: Applied Spectroscopy, SAGE Publications, Vol. 55, No. 2 ( 2001-02), p. 125-129
    Abstract: The absorption spectrum of gaseous 2,4,6-trinitrotoluene (TNT) was recorded by conventional absorption spectroscopy (AS) as well as cavity ringdown spectroscopy (CRDS) methods in the spectral regions 195–300 and 225–235 nm, respectively. These spectra were normalized by using the saturated TNT vapor-number density for the measured cell temperature to obtain the absorption cross section of TNT. No spectral features were found in the spectra; this result is consistent with a repulsive electronic excited state of TNT. The temperature dependence of the absorption coefficient of saturated TNT vapor was measured within the temperature range 5–110 °C. The limit of detection of TNT vapor by CRDS is less than 1 ppb. Real-time CRDS measurements of the TNT vapor density at 21 and 37 °C are presented. The TNT evaporation rates were found to be 7 × 108 and 4 × 10 10 molecules/cm 2 × s at 21 and 37 °C, respectively.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2001
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 8
    In: Applied Spectroscopy, SAGE Publications, Vol. 53, No. 10 ( 1999-10), p. 1161-1168
    Abstract: Laser desorption mass spectroscopy has been used to characterize both modern and ∼ 150-year-old daguerreotypes. Such investigations are a necessary prelude to attempts to clean them of tarnish and other contaminants by laser ablation of the surface layers. Both positive- and negative-ion time-of-flight spectra were obtained following YAG laser ablation/desorption at 1064, 532, and 355 nm. Major peaks obtained from several daguerreotypes reveal expected elements from the substrate (Ag, Cu) as well as the developing (Hg) and gilding (Au) processes. Silver clusters (Ag n ) may reflect surface desorption of molecules or, alternatively, aggregates formed in the ejection process. Silver sulfide molecules observed from old daguerreotypes are the signature of the tarnishing process.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1999
    detail.hit.zdb_id: 1474251-2
    SSG: 11
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2007
    In:  Applied Spectroscopy Vol. 61, No. 1 ( 2007-01), p. 25-31
    In: Applied Spectroscopy, SAGE Publications, Vol. 61, No. 1 ( 2007-01), p. 25-31
    Abstract: Raman spectroscopy has been identified as a potentially useful tool to collect evidence of past or present life on extraterrestrial bodies. However, it is limited by its inherently low signal strength. In this investigation, laboratory tests were conducted using surface-enhanced Raman spectroscopy (SERS) in an “inverted” mode to detect the presence of organic compounds that may be similar to possible biomarkers present on Mars. SERS was used to overcome the inherently low signal intensity of Raman spectroscopy and was an effective method for detecting small concentrations of organic compounds on a number of surfaces. For small organic molecules, dissolution of the molecule to be analyzed in a suitable solvent and depositing it on a prepared SERS substrate for analysis is possible. However, for larger molecules, an “inverted” SERS (iSERS) technique was shown to be effective. In iSERS, nanoparticles of silver or gold were deposited on the mineral substrate/organic compound to be analyzed. Benzotriazole, benzoic acid, and phthalic acid were used as test organic analogs and the iSERS technique was able to detect femtomole levels of the analytes. The interference from various mineral substrates was also examined. Different methods of depositing silver particles were evaluated, including ion beam-assisted vapor deposition and deposition from aqueous colloidal suspensions.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2007
    detail.hit.zdb_id: 1474251-2
    SSG: 11
    Location Call Number Limitation Availability
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