Search results for "WAVELENGTH"
showing 10 items of 741 documents
Excitonic energy level structure and pigment-protein interactions in the recombinant water-soluble chlorophyll protein. II. Spectral hole-burning exp…
2011
Persistent spectral hole burning at 4.5 K has been used to investigate the excitonic energy level structure and the excited state dynamics of the recombinant class-IIa water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The hole-burned spectra are composed of four main features: (i) a narrow zero-phonon hole (ZPH) at the burn wavelength, (ii) a number of vibrational ZPHs, (iii) a broad low-energy hole at ~665 and ~683 nm for chlorophyll b- and chlorophyll a-WSCP, respectively, and (iv) a second satellite hole at ~658 and ~673 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. The doublet of broad satellite holes is assigned to an excitonically coupled chlorophyll dim…
H-point standard additions method for resolution of overlapped chromatographic peaks with a conventional fluorescence detector. Determination of phen…
1996
The H-Point Standard Additions Method (HPSAM) is proposed in order to resolve overlapping peaks in liquid chromatography by using a conventional fluorescence detector. The method uses as analytical signals the heights or the areas obtained at two previously selected emission wavelengths, and good results are obtained for highly overlapping peaks with highly overlapping fluorescence spectra. The principal benefits of the method are the ease of finding the required wavelengths, its insensitivity to changes in the retention time of the peak from one injection to another, and the possibility of using it in highly or only partially overlapping peaks. We have applied the method to the determinati…
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Magnesium alloys (WE43 and ZE41) characterisation for laser applications
2004
International audience; One of the most important parameters in laser treatment is the quantity of beam energy absorbed by the substrate. Despite its important role played in laser processes, this factor is rarely available for the laser sources wavelengths and at high temperatures reached during such treatments. A series of experiments were carried out in order to characterise, from this point of view, two types of magnesium alloys, WE43 and ZE41, often used in laser applications (cladding, alloying, welding, etc.). The results represent an important step in order to understand Mg-alloys behaviour under laser beam action.
AX-PET: Concept, proof of principle and first results with phantoms
2010
AX-PET is a novel PET concept based on long crystals axially arranged and orthogonal Wavelength shifter (WLS) strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD). Its design was conceived in order to reduce the parallax error and simultaneously improve spatial resolution and sensitivity. The assessment of the AX-PET concept and potential was carried out through a set of measurements comprising individual module characterizations and scans in coincidence mode of point-like and extended sources. The estimated energy and spatial resolutions from point-like measurements are R FWHM =11.6% (at 511 keV) and 1.7–1.9 mm (FWHM) respectively as measured with point-like sour…
Multi-level optimization of a fiber transmission system via nonlinearity management
2006
Nonlinearity management is explored as a complete tool to obtain maximum transmission reach in a WDM fiber transmission system, making it possible to optimize multiple system parameters, including optimal dispersion pre-compensation, with fast simulations based on the continuous-wave approximation. © 2006 Optical Society of America.
Performance Comparison of Duobinary Modulation Formats for 40 Gb/s Long-Haul WDM Transmissions
2006
With their compact spectrum and high tolerance to residual chromatic dispersion, duobinary formats are attractive for the deployment of 40 Gb/s technology on 10 Gb/s WDM Long-Haul transmission infrastructures. Here, we compare the robustness of various duobinary formats when facing 40 Gb/s transmission impairments.
Extended scale-invariant pattern recognition with white-light illumination.
2000
A previous method of obtaining scale-invariance detection with white-light illumination has been improved on. We were able to detect different scaled versions of the target up to a magnification factor equal to 2. We simultaneously detected several versions in the same scene, because each scale factor is codified in a different wavelength. Experimental results demonstrate the proposed technique and show the utility of the method.
Multilevel system optimisation via nonlinearity management
2006
Nonlinearity management is explored as a multilevel tool to obtain maximum transmission reach in a WDM system. A technique for the fast calculation of the optimal dispersion pre-compensation in systems with distributed amplification is proposed.
Fluctuating Interfaces in Liquid Crystals
2008
We review and compare recent work on the properties of fluctuating interfaces between nematic and isotropic liquid-crystalline phases. Molecular dynamics and Monte Carlo simulations have been carried out for systems of ellipsoids and hard rods with aspect ratio 15:1, and the fluctuation spectrum of interface positions (the capillary wave spectrum) has been analyzed. In addition, the capillary wave spectrum has been calculated analytically within the Landau-de Gennes theory. The theory predicts that the interfacial fluctuations can be described in terms of a wave vector dependent interfacial tension, which is anisotropic at small wavelengths (stiff director regime) and becomes isotropic at l…