Troisième atelier Trattoria consacré au transfert radiatif atmosphérique

Le Cnes, en collaboration avec le CNRS/Insu et Météo-France, organisait en janvier 2020 à Toulouse la troisième édition de l'atelier Trattoria (Transfert radiatif dans les atmosphères terrestres pour les observations spatiales). Cet atelier est principalement consacré aux codes de transfert radiatif dans l'atmosphère terrestre pour les applications de télédétection spatiale, opérant sur l'ensemble de la gamme des longueurs d'onde de l'ultraviolet aux micro-ondes. Ces codes numériques sont fondamentaux pour la préparation des instruments de télédétection, ainsi que pour le traitement et l'exploitation des données satellitaires. Cet atelier était ouvert à tous les chercheurs, ingénieurs, post-doctorants et doctorants du domaine. Les résultats et recommandations de l'atelier doivent servir de guide au Cnes et aux divers participants et utilisateurs français et européens de codes de transfert radiatif. The CNES, in collaboration with the CNRS/INSU and Météo-France, organized in January 2020 in Toulouse the third edition of the Trattoria workshop (Transfert radiatif dans les atmosphères terrestres pour les observations spatiales). This workshop is mainly devoted to radiation transfer codes in the Earth's atmosphere for space remote sensing applications, operating over the entire wavelength range from ultraviolet to microwaves. These numerical codes are fundamental for the preparation of remote sensing instruments, as well as for the processing and exploitation of satellite data. This workshop was open to all researchers, engineers, post-doctoral and doctoral students in the field. The results and recommendations of the workshop should serve as a "guide" for CNES and the various French and European participants and users of radiative transfer codes.

Nondestructive classification of mung bean seeds by single kernel near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) in the range 900–1700 nm was performed to develop a classifying model for dead seeds of mung bean using single kernel measurements. The use of the combination of transmission-absorption spectra and reflection-absorption spectra was determined to yield a better classification performance (87.88%) than the use of only transmission-absorption spectra (81.31%). The effect of the orientation of the mung bean with respect to the light source on its absorbance was investigated. The results showed that hilum-down orientation exhibited the highest absorbance compared to the hilum-up and hilum-parallel-to-ground orientations. We subsequently examined the spectral information related to the seed orientation by developing a classifying model for seed orientation. The wavelengths associated with classification based on seed orientation were obtained. Finally, we determined that the re-developed classifying model excluding the wavelengths related to the seed orientation afforded better accuracy (89.39%) than that using the entire wavelength range (87.88%).

Enhanced Infrared Normal Spectral Emissivity of Microstructured Silicon at 100 to 200°C

The infrared normal spectral emissivity of microstructured silicon prepared by femtosecond laser was measured for the middle infrared waveband at temperature range 100 to 200°C. Compared to that of flat silicon, emissivity was enhanced over the entire wavelength range. For a sample with different spike height, the minimum emissivity at a temperature of 100°C is more than 0.6. Although the average emissivity is less than Nextel- Velvet-811-21 Coating , it can be used stably at more wide temperature ranges. These results show the potential for microstructured silicon to be used as a flat blackbody source or silicon-based devices.

Study of uranyl(VI) malonate complexation by time resolved laser-induced fluorescence spectroscopy (TRLFS)

SummaryThe uranyl(VI) malonate complex formation was studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at pH 4 and an ionic strength of 0.1 M NaClOThe measured fluorescence lifetimes of the 1:1 and 1:2 uranyl(VI) malonate complexes are 1.24 ± 0.02 µs and 6.48 ± 0.02 µs, respectively. The fluorescence lifetime of the uranyl(VI) ion is 1.57 ± 0.06 µs in 0.1 M perchloric media. The main fluorescence bands of the malonate complexes show a bathochromic shift compared to the uranyl(VI) ion and are centered at 494 nm, 515 nm and 540 nm for the 1:1 complexes and at 496 nm, 517 nm and 542 nm for the 1:2 complex. The spectra of the individual uranyl(VI) malonate complexes were calculated using a multi exponential fluorescence decay function for each intensity value at each wavelength, covering the entire wavelength range. Stability constants were determined for the complexes UO

Set of Secondary Emission Standards for Calibration of the Spectral Responsivity in Emission Spectroscopy

Technical spectra are reported for a series of six secondary emission standards based on the commercially available fluorophors: tryptophan, α-NPO, tetraphenylbutadiene, coumarin 153, DCM, and LDS 751. These spectra cover the wavelength range between 300 and 800 nm with significant spectral overlap and conform to the requirements of secondary emission standards. Standard emission spectra are determined by averaging the technical spectra obtained from three independently calibrated fluorescence spectrometers. A method for generating the wavelength-dependent correction file by using these standards is outlined. Comparison to the National Bureau of Standards (NBS)-reported quinine sulfate spectrum illustrates the accuracy of both the emission standards and the method of generating a complete emission correction file. With the use of the standards and method reported here, the accuracy of the emission correction is estimated to be better than 10% for the entire wavelength range and significantly better over the wavelength region of a typical spectrum.

Structural characterization of different insulating films by spectroscopic ellipsometry and grazing x‐ray reflectance

Spectroscopic Ellipsometry (SE) and Grazing X‐ray Reflectance (GXR) techniques are applied for different insulating films to determine precisely the thickness and optical indices of the layers. Antireflective coatings for microlithography in the DUV range are first analyzed. In the infrared range the layers are transparent and one can take into account the optical index of the layers by a simple dispersion law. Thicknesses obtained by this method are checked by the GXR technique. Extraction of the optical indices from UV to IR is made very accurately taking into account different SE measurements at various incident angles simultaneously. Amorphous carbon thin films are also analyzed in the same way. The main difference is that the layer is absorbant in the entire wavelength range. In this case, a first characterization by the GXR technique is essential to extract the thickness of the layer. Then the optical indices of the layer can be extracted very accurately by SE.

Energy Distribution of Planetary Nebulae (UV to Radio)

The past decade has seen significant progress in our understanding of spectral energy distribution of planetary nebulae over the entire wavelength range from UV to radio. In this review we show the detailed breakdown of the energy budget for a planetary nebula as a system of the three components, i.e., the central star, the gaseous nebula and the dust shell. This picture of the energy distribution is further discussed in the context of planetary nebula evolution.

Extinction curves for graphite-silicate grain mixtures

Mixtures of graphite particles ejected from carbon stars and silicates from oxygen-rich giants are capable of producing excellent fits to the observed interstellar extinction curve. The fits extend over the entire wavelength range of the observations, and include a hump at ~ 2200 Å in the ultraviolet due to the graphite components of the mixtures. The agreement with the observed extinction curve remains good if the small silicate particles acquire mantles of either ice or solid H2. If no mantles are present around the silicate grains comparable mass densities of graphite and silicates are indicated; if mantles of either ice or solid H2 are present the mass density of silicates may be an order of magnitude below that of graphite in the interstellar medium.