Search results for "SPECTRA"

Effect of Soil Moisture on the Angular Variation of Thermal Infrared Emissivity of Inorganic Soils

2014

Emissivity is influenced by different factors. This study deals with the effect of the soil moisture (SM) content on the zenithal (θ) variation of ratio-to-nadir emissivity (εr), for a wide variety of inorganic bare soils. To retrieve εr, a goniometer assembly was used, together with two identical CIMEL Electronique CE312-2 radiometers working at six spectral bands within 7.7-14.3 μm, performing simultaneous radiance measurements at different combinations of zenith and azimuth angles. The results showed that the effect of SM upon εr(θ) is different depending on the spectral range and textural composition of the sample. Sandy soils showed a decrease of εr(θ) from nadir up to 0.132 for θ ≥ 40…

High-temperature emission spectroscopy of methane

2008

International audience; A high-enthalpy source (HES) has been developed in Rennes either to heat gases up to 2000K in local thermodynamic equilibrium (LTE) or to generate hypersonic expansions. The HES prototype has been associated with a high-resolution Bruker IFS 120 HR Fourier transform spectrometer to record emission spectra of hot gases, in LTE conditions. A series of emission spectra of methane has been obtained at 1005, 1365, 1485, 1625 and 1820K in the pentad spectral region located around 3000 cm1, at Doppler-limited resolution (0.02 cm1). Spectra have been corrected for the transmission function that strongly affects the infrared radiation emitted by the hot gas. Line-integrated a…

Ultralow chirp photonic crystal fiber Mach-Zehnder interferometer

2018

A photonic crystal fiber Mach-Zehnder interferometer design was optimized to obtain high performance and ultralow chirp. Two long-period gratings were used to excite the cladding modes, and the rich structure of the cladding was tailored to obtain a slightly chirped free spectral range, as required by the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) Norm G.694.1. Finally, a fabrication tolerance analysis was performed. The advantages of the proposed device are an ultralow chirp, high bandwidth, and fabrication robustness tolerance.

Symmetry of valence states of Heusler compounds explored by linear dichroism in hard-x-ray photoelectron spectroscopy.

2011

This study reports on the linear dichroism in angular-resolved photoemission from the valence band of the Heusler compounds ${\mathrm{NiTi}}_{0.9}{\mathrm{Sc}}_{0.1}\mathrm{Sn}$ and NiMnSb. High-resolution photoelectron spectroscopy was performed with an excitation energy of $h\ensuremath{\nu}=7.938\text{ }\text{ }\mathrm{keV}$. The linear polarization of the photons was changed using an in-vacuum diamond phase retarder. The valence band spectra exhibit the typical structure expected from first-principles calculations of the electronic structure of these compounds. Noticeable linear dichroism is found in the valence band of both materials, and this allows for a symmetry analysis of the cont…

Optical rotary power at the resonance of the Terbium 7F6→5D4 line in Terbium Gallium Garnet

1998

Abstract The Tb 3+ absorption line 7 F 6 → 5 D 4 of the Terbium Gallium Garnet crystal is excited with an Argon ion laser. The Verdet's constant has been determined and reported against 1/ λ 2 , showing no significant resonant behaviour at absorption resonance. The utility and the constraints of the crystal at this particular resonant wavelength are pointed out.

Shifting the Photoresponse of ZnO Nanowires into the Visible Spectral Range by Surface Functionalization with Tailor-Made Carbon Nanodots

2018

We report on the surface functionalization of ZnO nanowires (NWs) with specifically synthesized carbon nanodots (C-dots, CDs) that allows us to shift the photoresponse of the NWs far into the visib...

2014

Hard x-ray photoelectron spectroscopy (HAXPES) is used to investigate the intrinsic electronic properties of single crystal epitaxial CdO(100) thin films grown by metal organic vapor phase epitaxy (MOVPE). The reduced surface sensitivity of the HAXPES technique relaxes stringent surface preparation requirements, thereby allowing the measurement of as-grown samples with intrinsically higher carrier concentration (n=2.4×1020cm−3). High-resolution HAXPES spectra of the valence band and core levels measured at photon energy of 6054 eV are presented. The effects of conduction band filling and band gap renormalization are discussed to explain the observed binding energy shifts. The measured bandw…

Study of As and Tl high-frequency electrodeless lamps for Zeeman absorption spectroscopy

2020

High-frequency electrodeless light sources are known as bright radiators with the line spectrum, characterized by high intensities and narrow line shapes. The lamp balloons are mostly made of quartz and filled with a metal and buffer gas. These light sources must be optimized for each application in accordance with the specific requirements of radiation quality, lifetime, and stability. This work is devoted to the diagnostic of high-frequency electrodeless light sources for their use in high precision atomic absorption analyzers and other applications like disinfection. The spectral line intensities and profiles were studied in discharges with arsenic and thallium fillings. Special attentio…

Unmixing of human skin optical reflectance maps by Non-negative Matrix Factorization algorithm

2013

International audience; We present in this paper the decomposition of human skin absorption spectra with a Non-negative Matrix Factorization method. In doing so, we are able to quantify the relative proportion of the main chromophores present in the epidermis and the dermis. We present experimental results showing that we obtain a good estimate of melanin and hemoglobin concentrations. Our approach has been validated by analyzing the human skin absorption spectra in areas of healthy skin and areas affected by melasma on eight patients.

Thermal restraint of a bacterial exopolysaccharide of shallow vent origin

2018

This is the post-print version of the following article: "Thermal restraint of a bacterial exopolysaccharide of shallow vent origin", which has been published in final form at https://www.sciencedirect.com/science/article/pii/S0141813018308250?via%3Dihub; International audience; To dynamically characterize the thermal properties of the fructose-rich exopolysaccharide (EPS1-T14), produced by themarine thermophilic Bacillus licheniformis T14, the Attenuated Total Reflectance Fourier Transform Infra-Redspectroscopy was coupled to variable temperature ranging from ambient to 80 °C.The spectra were analyzed by the following innovative mathematical tools: i) non-ideal spectral deviation, ii) OHst…