Search results for "resolution."
showing 10 items of 1825 documents
Hydrogen CARS thermometry in H2-N2 mixtures at high pressure and medium temperatures: influence of linewidths models
2000
International audience; In order to improve the accuracy of H2 CARS thermometry, H2 Q-branch CARS spectra have been recorded for various H2-N2 mixtures in a high-pressure cell at different pressures and temperatures (up to 40 bar and 875 K). Due to the low spectral resolution of broadband CARS experiments, the relevant spectral lineshape factor is the linewidth ratio G(Q(3))/G(Q(1)), since Q(1) and Q(3) are the most intense lines of the Q-branch spectrum in this temperature range. For the first time, the speed-inhomogeneous effects are accounted for in the simulation of the CARS profiles. The evaluated temperatures are in good agreement with reference values obtained by thermocouples. The s…
Magnetic octupole moment of Yb-173 using collinear laser spectroscopy
2021
The hyperfine constants of the $4{f}^{14}6s6p^{3}P_{2}^{o}$ state in neutral Yb have been measured using three different dipole transitions. This state was recently shown to have a comparatively large hyperfine magnetic octupole splitting, and thus a puzzlingly large magnetic octupole moment. The measurement is performed using collinear laser spectroscopy on a fast atomic beam, which provides a straightforward route to probing long-lived metastable atomic states with high resolution. From the combined analysis of all three lines we find no significant evidence for a nonzero octupole moment in $^{173}\mathrm{Yb}$.
Validation of daily global solar irradiation images from MSG over Spain
2013
Abstract Daily irradiation images over Spain – area that embraces a highly heterogeneous landscape, climatic conditions and relief – are calculated from the down-welling surface short-wave radiation flux (DSSF) product derived from the MSG SEVIRI images. Their analysis and validation is carried out using two different station networks along the year 2008. The first network covers the peninsular Spain and Balearic islands. A denser one, covering the Catalonian territory and including many stations located in rugged terrain, is found useful to assess the elevation correction to be applied to the images. The statistics from the validation using the first network shows a relative mean bias of a…
A VLBI study of the wind-wind collision region in the massive multiple HD 167971
2019
Context. Colliding winds in massive binaries are able to accelerate particles up to relativistic speeds as the result of the interaction between the winds of the different stellar components. HD 167971 exhibits this phenomenon which makes it a strong radio source. Aims. We aim at characterizing the morphology of the radio emission and its dependence on the orbital motion, traced independently by near-infrared (NIR) interferometry of both the spectroscopic binary and the tertiary component comprising HD 167971. Methods. We analyze 2006 and 2016 very long baseline interferometric data at C and X bands. We complement our analysis with a geometrical model of the wind-wind collision region and a…
Determination of macro, micro nutrient and trace element concentrations in Indian medicinal and vegetable leaves using instrumental neutron activatio…
1999
Abstract Leafy samples often used as medicine in the Indian Ayurvedic system and vegetables were analyzed for 20 elements (As, Ba, Br, Ca, Ce, Cr, Cs, Co, Eu, Fe, K, La, Na, Rb, Sb, Sc, Sm, Sr, Th, Zn) by employing Instrumental Neutron Activation Analysis (INAA). The samples were irradiated at the 100 kW TRIGA-MAINZ nuclear reactor and the induced activities were counted by gamma ray spectrometry using an efficiency calibrated high resolution High Purity Germanium (HPGe) detector. The concentration of the elements in the medicinal and vegetable leaves and their biological effects on human beings are discussed.
Image enhancement in photoemission electron microscopy by means of imaging time-of-flight analysis
2004
Abstract Photoemission electron microscopy (PEEM) is widely used in combination with synchrotron sources as a powerful tool to observe chemical and magnetic properties of metal and semiconductor surfaces. Presently, the resolution limit of these instruments using soft-X-ray excitation is limited to about 50 nm, because of the chromatic aberation of the electron optics used. Various sophisticated approaches have thus been reported for enhancing the spatial resolution in photoemission electron microscopy. This work demonstrates the use of a simple imaging energy filter based on electron time-of-flight (ToF) selection. The spatial resolution could be improved dramatically, even though the inst…
NanoESCA: imaging UPS and XPS with high energy resolution
2005
Abstract A novel imaging electron spectrometer has been used for laterally resolved ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) in the soft X-ray range. The instrument is based on a high-resolution emission microscope optics using a cathode lens and an imaging dispersive analyser. The analyser is corrected for the leading aberration term ( α 2 -term) by means of two hemispherical analysers in antisymmetric configuration with an appropriate transfer lens. Small-area spectra as well as energy-filtered images have been taken in the soft X-ray range for a meteorite sample and in the range of the d-band of a Cu polycrystal. An energy resolution of 106 …
Fast elemental mapping and magnetic imaging with high lateral resolution using a novel photoemission microscope
1998
Abstract Using tunable soft X-ray synchrotron radiation and a new-generation photoemission electron microscope with integral sample stage and microarea selector, elemental images and local XANES spectra have been measured. Given the present conditions (PM3 at BESSY), the lateral resolution was in the range of 130 nm with the potential of considerable improvement with high-brilliance sources (a base resolution of 25 nm was obtained in threshold photoemission). Measurements at the oxygen K-edge demonstrate that differences in the local chemical environment of the emitter atom are clearly revealed and can thus be used as a fingerprint technique for its chemical state and geometrical surroundin…
Multipole WIEN-filter for a high-resolution X-PEEM
1997
Abstract The development and construction of an X-PEEM with integral multipole WIEN-filter for spectromicroscopy with high lateral resolution is presented. All relevant electron-optical properties of the filter have been examined by field and trajectory calculations. Electric and magnetic multipole components (dipole, quadrupole and hexapole) can be chosen independently from each other, thus allowing electron-optical corrections. Theoretical values for the lateral resolution are in the range of 10 nm, experimental values of ≤25 nm have been achieved using the column without filter. The instrument is designed in particular for the use of Sychrotron radiation as well as new, high-brilliance l…
Spherical top data system (STDS) software for the simulation of spherical top spectra
1998
Abstract The Spherical Top Data System (STDS) software package for the simulation of spherical top spectra is presented. It consists of a single UNIX script with self-explanatory arguments allowing the non-expert user to calculate spectra from the results of the high resolution analyses performed over the recent decades on this type of molecules. More than one hundred parameter files are presently available including various band systems of 16 molecular species (among which methane is the most documented) and various types of calculations: rovibrational energy levels, i.r. absorption, Raman scattering and Stark coefficients. STDS is freely accessible by anonymous ftp at jupiter.u-bourgogne.…