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Absorption Spectra

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Toby K. Westberry – One of the best experts on this subject based on the ideXlab platform.

  • Decomposition of in situ particulate Absorption Spectra
    Methods in Oceanography, 2013
    Co-Authors: Alison Chase, Emmanuel Boss, Ronald Zaneveld, Annick Bricaud, Hervé Claustre, Josephine Ras, Giorgio Dall'olmo, Toby K. Westberry
    Abstract:

    A global dataset of in situ particulate Absorption Spectra has been decomposed into component functions representing Absorption by phytoplankton pigments and non-algal particles. The magnitudes of component Gaussian functions, used to represent Absorption by individual or groups of pigments, are well correlated with pigment concentrations determined using High Performance Liquid ChroChromatography. We are able to predict the presence of chlorophylls a,ba,b, and cc, as well as two different groups of summed carotenoid pigments with percent errors between 30% and 57%. Existing methods of analysis of particulate Absorption Spectra measured in situ provide for only chlorophyll aa; the method presented here, using high Spectral resolution particulate Absorption, shows the ability to obtain the concentrations of additional pigments, allowing for more detailed studies of phytoplankton ecology than currently possible with in-situ spectroscopy.

William E. Nixon – One of the best experts on this subject based on the ideXlab platform.

  • Terahertz Absorption Spectra of nitromethane
    Journal of Quantitative Spectroscopy and Radiative Transfer, 2011
    Co-Authors: Elizabeth J. Slingerland, Edwin G. E. Jahngen, Thomas M. Goyette, Robert H. Giles, William E. Nixon
    Abstract:

    Abstract Nitromethane, with its heavy frame and internal rotator, readily evaporates into the atmosphere making it an ideal candidate for remote sensing. Here we present the Absorption Spectra of gas-phase nitromethane between 9 and 50 cm −1 . Measurements were taken using a Bruker IFS 66v Fourier transform far-infrared (FTIR) spectrometer at a resolution of 0.12 cm −1 (0.0036 THz) from 9 to 40 cm −1 and a Bruker Vertex 80v FTIR spectrometer with a resolution of 0.0075 cm −1 (0.00226 THz) from 10 to 50 cm −1 . The Absorption Spectra were measured at multiple pathlengths ranging from 2 to 6 m. These measurements were used to calculate the Absorption coefficient of nitromethane as a function of wavenumber.

Charles R. Boston – One of the best experts on this subject based on the ideXlab platform.

  • Absorption Spectra OF FUSED-SALT SOLUTIONS
    Annals of the New York Academy of Sciences, 2006
    Co-Authors: G. Pedro Smith, Charles R. Boston
    Abstract:

    Studies were made of the ultraviolet Absorption Spectra of the oxy- anions nitrate, chromate, and nitrate in a variety of fused-salt mixtures. (W.L.H.)

Matthew A. Linkswiler – One of the best experts on this subject based on the ideXlab platform.

  • An inverse modeling approach to estimating phytoplankton pigment concentrations from phytoplankton Absorption Spectra
    Journal of Geophysical Research, 2011
    Co-Authors: John R. Moisan, Tiffany Moisan, Matthew A. Linkswiler
    Abstract:

    Phytoplankton Absorption Spectra and High-Performance Liquid ChroChromatography (HPLC) pigment observations from the Eastern U.S. and global observations from NASA‘s SeaBASS archive are used in a linear inverse calculation to extract pigment-specific Absorption Spectra. Using these pigment-specific Absorption Spectra to reconstruct the phytoplankton Absorption Spectra results in high correlations at all visible wavelengths (r(sup 2) from 0.83 to 0.98), and linear regressions (slopes ranging from 0.8 to 1.1). Higher correlations (r(sup 2) from 0.75 to 1.00) are obtained in the visible portion of the Spectra when the total phytoplankton Absorption Spectra are unpackaged by multiplying the entire Spectra by a factor that sets the total Absorption at 675 nm to that expected from Absorption Spectra reconstruction using measured pigment concentrations and laboratory-derived pigment-specific Absorption Spectra. The derived pigment-specific Absorption Spectra were further used with the total phytoplankton Absorption Spectra in a second linear inverse calculation to estimate the various phytoplankton HPLC pigments. A comparison between the estimated and measured pigment concentrations for the 18 pigment fields showed good correlations (r(sup 2) greater than 0.5) for 7 pigments and very good correlations (r(sup 2) greater than 0.7) for chlorophyll a and fucoxanthin. Higher correlations result when the analysis is carried out at more local geographic scales. The ability to estimate phytoplankton pigments using pigment-specific Absorption Spectra is critical for using hyperSpectral inverse models to retrieve phytoplankton pigment concentrations and other Inherent Optical Properties (IOPs) from passive remote sensing observations.

Alison Chase – One of the best experts on this subject based on the ideXlab platform.

  • Decomposition of in situ particulate Absorption Spectra
    Methods in Oceanography, 2013
    Co-Authors: Alison Chase, Emmanuel Boss, Ronald Zaneveld, Annick Bricaud, Hervé Claustre, Josephine Ras, Giorgio Dall'olmo, Toby K. Westberry
    Abstract:

    A global dataset of in situ particulate Absorption Spectra has been decomposed into component functions representing Absorption by phytoplankton pigments and non-algal particles. The magnitudes of component Gaussian functions, used to represent Absorption by individual or groups of pigments, are well correlated with pigment concentrations determined using High Performance Liquid Chromatography. We are able to predict the presence of chlorophylls a,ba,b, and cc, as well as two different groups of summed carotenoid pigments with percent errors between 30% and 57%. Existing methods of analysis of particulate Absorption Spectra measured in situ provide for only chlorophyll aa; the method presented here, using high Spectral resolution particulate Absorption, shows the ability to obtain the concentrations of additional pigments, allowing for more detailed studies of phytoplankton ecology than currently possible with in-situ spectroscopy.