Search results for "WAVELENGTH"
showing 10 items of 741 documents
Calculations of the variability of ice cloud radiative properties at selected solar wavelengths
2010
This study shows that there is surprising little difference in values of reflectance, absorptance, and transmittance for many of the intermediate-size particle spectra. Parrticle size distributions with mode radii ranging from approximately 50 to 300 microAm, irrespective of particle shape and nearly independent of the choice of size distribution representation, give relatively similar flux values. The very small particle sizes, however, have significantly larger values of reflectance and transmittance with corresponding smaller values of absorptance than do the larger particle sizes. The very large particle modes produce very small values of reflectance and transmittance along with very la…
Molecular Multi‐Wavelength Optical Anion Sensors
2010
Polychromatic fingerprinting of simple anions (halides, oxo anions) is achieved by employing neutral and charged multicolor fluorescent probes based on ferrocene-spaced dansyl and naphthyl groups (1/1 + ; 2/2 + ). The conformation of the neutral double dye sensor 2 has been elucidated by NMR spectroscopic techniques (in solution), by X-ray crystallography (solid state) and by DFT calculations (gas phase). The double-dye receptors 2/2 + exhibit specific emission responses in the presence of anions X- when excited at the absorption maxima of the dyes (fingerprint).
Strongly decelerated expansion of SN 1979C
2002
We observed SN1979C in M100 on 4 June 1999, about twenty years after explosion, with a very sensitive four-antenna VLBI array at the wavelength of 18cm. The distance to M100 and the expansion velocities are such that the supernova cannot be fully resolved by our Earth-wide array. Model-dependent sizes for the source have been determined and compared with previous results. We conclude that the supernova shock was initially in free expansion for 6 +/- 2 yrs and then experienced a very strong deceleration. The onset of deceleration took place a few years before the abrupt trend change in the integrated radio flux density curves. We estimate the shocked swept-up mass to be about 1.6 solar masse…
Classical ionic fluids in the mean spherical approximation
1980
The recently obtained analytical solution of the mean spherical approximation has been used to calculate thermodynamic and structural properties of aqueous solutions of asymmetric electrolytes. The same approximation has also been used to calculate structure functions of pure and mixed molten salts. The agreement between experimental or “quasi-experimental” structure functions and those obtained within the framework of the MSA is quite good especially when the ionic radii are obtained by fitting the long wavelength limit of the structure functions to the isothermal compressibility of the system, under the condition that the diameter ratio is the same as in the crystal.
The THESEUS space mission concept: science case, design and expected performances
2018
THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5¿1 arcmin localization, an energy band extending from several MeV down to 0.3¿keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7¿m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing …
The Determination of the Reaction Rate for the First Step in a Consecutive Reaction A → B → C by Absorbance Measurements Using the Wavelength of the …
1977
Kinetic experiments are often followed by spectroscopic measurements in the visible or near ultraviolet region. The advantage is not only that the results can be recorded continuously, which makes very fast reactions accessible, but also that very low concentrations of substrates can be used. This means that only very small amounts are required and, more important perhaps, that reagents can be used in excess. Thus pseudomonomolecular conditions and first-order kinetics often can be achieved easily.
Spectral dependence of purely-Kerr driven filamentation in air and argon
2010
5 pags, 4 figs.-- PACS number(s): 42.65.Jx, 42.65.Tg, 78.20.Ci. -- Publisher error corrected 27 September 2010, Erratum Phys. Rev. A 82, 039905 (2010): https://doi.org/10.1103/PhysRevA.82.033826
Characterization of PP-cLT Waveguides for Second-Harmonic-Generation and Wavelength-Conversion in the C + L Band of Optical Communications
2010
We report the characterization of single-mode optical waveguides at telecom wavelength, realized in congruent lithium-tantalate. We demonstrate that waveguides realized by proton-exchange show a nonlinear coefficient matching that expected in a bulk crystal.
A compact Raman microprobe/microscope: Analysis of polydiacetylene Langmuir and Langmuir-Blodgett films
1991
A compact Raman microprobe/microscope has been developed which contains no wavelength dispersive elements. Multilayer dielectric filters, tuned by rotation, provide sufficient wavelength selectivity for taking Raman spectra and forming Raman images of samples as small as 1 μm in diameter. The application of the instrument is demonstrated by Raman spectra and images of polydiacetylene Langmuir and Langmuir-Blodgett films.
A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer.
2016
The chemical architecture of lanthanide doped core–shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ∼980 to the more relevant ∼808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb–Er co-doped core nanoparticles with the Yb–Nd co-doped shell, we have intentionally combined temperature dependent Er u…