Analysis of sodium copper chlorophyllin and sodium magnesium chlorophyllin by time-domain THz spectroscopy

The terahertz absorption spectra of sodium magnesium chlorophyllin (Chl-Mg-Na) and sodium copper chlorophyllin (Cu-Chl), two major members of the chlorophyll derivative family, have been measured in the range 0.2-2.5 THz, at room temperature. The capability of terahertz spectroscopy for quantitative characterization of Chl-Mg-Na intermolecular vibrations was investigated and the sensitivity of transitions with degree of hydration by changes in the molecular environment was examined. For the Cu-Chl derivative, a broad feature was observed around 1.8 THz which currently hinders clear Cu-Chl identification and quantification

Investigating the low-frequency vibrations of chlorophyll derivatives using terahertz spectroscopy

The terahertz absorption spectra of sodium magnesium chlorophyllin (Chl-Mg-Na) and sodium copper chlorophyllin (Cu-Chl), two major members of the chlorophyll derivative family, have been measured in the range 0.2-3.0 THz (6.6-100 cm-1), at room temperature. Additionally, surface-enhanced Raman scattering spectroscopy was used to supplement data in the higher frequency range. The capability of terahertz spectroscopy for quantitative characterization of Chl-Mg-Na intermolecular vibrations was investigated and the sensitivity of the 1.82-THz feature with degree of hydration by changes in the molecular environment was examined. For Cu-Chl derivative, a broad feature was observed around 1.8 THz which currently hinders clear Cu-Chl identification and quantification

Temperature-dependent low-frequency vibrational spectra of sodium magnesium chlorophyllin

Terahertz time-domain spectroscopy has been used to investigate the vibrational spectra of polycrystalline sodium magnesium chlorophyllin - one of the natural derivatives of chlorophyll - over the temperature range 88 K–298 K. A number of well-resolved absorption peaks were observed in the frequency range 0.2–2.5 THz, which are interpreted as originating from mixed character of intramolecular and intermolecular vibration modes. As the temperature is increased, the observed absorption features resolve into broader peaks. The peak centered at 1.83 THz shifts towards higher frequencies, indicating that for this feature, significant intermolecular anharmonicity exist

Pair Correlations in a Bidisperse Ferrofluid in an External Magnetic Field:Theory and Computer Simulations

The pair distribution function g(r) for a ferrofluid modeled by a bidisperse system of dipolar hard spheres is calculated. The influence of an external uniform magnetic field and polydispersity on g(r) and the related structure factor is studied. The calculation is performed by diagrammatic expansion methods within the thermodynamic perturbation theory in terms of the particle number density and the interparticle dipole–dipole interaction strength. Analytical expressions are provided for the pair distribution function to within the first order in number density and the second order in dipole–dipole interaction strength. The constructed theory is compared with the results of computer (Monte Carlo) simulations to determine the range of its validity. The scattering structure factor is determined using the Fourier transform of the pair correlation func-tion g(r) – 1. The influence of the granulometric composition and magnetic field strength on the height and position of the first peak of the structure factor that is most amenable to an experimental study is analyzed. The data obtained can serve as a basis for interpreting the experimental small[1]angle neutron scattering results and determining the regularities in the behavior of the structure factor, its dependence on the fractional com-position of a ferrofluid, interparticle correlations, and external magnetic field. © Pleiades Publishing, Inc., 2014

Size-dependent harvesting modifies the trophic niche of medaka Oryzias latipes in a mesocosm experiment

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Humusica 3 : reviews, applications, tools

Urban ecosystems are increasingly recognized as key providers of ecosystem services. Among them, green roofs are particularly fashionable, and are in high demand by citizens, politicians, urban planners and architects. Surprisingly, the functioning of green roofs and the impact of substrate type have been so far poorly studied and impede to optimize a green roof and its substrate to provide targeted services. This article thus discusses the different types of substrate that can be used for green roof and outlines the possible consequences for green roof functioning

Terahertz vibrational modes of sodium magnesium chlorophyllin and chlorophyll in plant leaves

The low-frequency (terahertz) vibrational spectroscopy has been investigated experimentally for two chlorophyll species, Chl- and one of its magnesium derivatives (Chl-Mg-Na). The combination of terahertz time-domain spectroscopy and Fourier transform infrared spectroscopy has enabled a broad frequency range to be covered (0.2 to 18 THz). For Chl-Mg-Na, the terahertz spectra show clear and well-marked features at 1.44, 1.64, and 1.83 THz dominated by intermolecular interactions. The frequency dependent refractive index and absorption coefficient of Chl-Mg-Na were both determined using the Fit@TDS software. Below 1.0 THz, a refractive index of 2.09 was measured. In order to acquire further understanding of the observed vibrational modes, a detailed study of the temperature dependence of the line positions of the lowest modes in Chl-Mg-Na was performed. As the temperature was increased from 88 K to 298 K, the feature at 1.83 THz experienced a notable red shift of frequency and line shape broadening, whereas the feature at 1.44 THz showed little change. These results suggest that the 1.83 THz feature is dominated by intermolecular motions occurring over the crystalline unit cell of the Chl-Mg-Na molecular crystal. Finally, terahertz time-domain spectroscopy was used to acquire the spectra of an ornamental plant bearing yellow-green variegated leaves (ivy, Aureomarginata variety), the yellow sectors having lower chlorophyll content compared to the green sectors. In dehydrated green tissue, the chlorophyll molecules showed well-marked intermolecular vibrational modes at 1.86 THz, indicating that chlorophyll molecules are prone to packing with an ordered molecular arrangement. These results demonstrate the potential application of THz spectroscopy in the field of agronomy

Terahertz InP DHBT-Based Detectors for Studies of Water Status of Sorghum Leaves

We present experimental studies of THz detection by different Heterojunction Bipolar Transistors (HBTs) fabricated using InP technology. We also show that the sensitive HBTs detectors can be used for THz spectroscopy and 2D THz imaging to study how the water content affects the polarization rate and biattenuation in fibrous sorghum leaf