Spectroscopic studies of Er3þ/Yb3þ co-doped (Ba,La)-fluorotellurite glass composition have been carried out using standard experimental and theoretical methods. Quantitative analyses of the room temperature absorption and emission spectra as well as the emission lifetimes yield various important spectroscopic parameters such as the radiative decay rates, fluorescence branching ratios, and emiss...

The internal dust extinction in spiral galaxies can affect our understanding of their structure and morphology, as well as our perception of the distant universe in the background. The intrinsic properties of the stellar and dust components can be studied by comparing the observed appearance of a dusty spiral in the optical with a radiative transfer model. The absorbed starlight is re-radiated ...

ON THE NATURE OF EXCITED STATES IN RUTHENIUM COMPLEXES:TOWARDS RENEWABLE ENERGYbyRYAN ANTONIO THOMASAugust 2015 Advisors: Prof. John F. Endicott and Prof. Cláudio N. Verani Major: Chemistry (Analytical) Degree: Doctor of Philosophy The 77 K radiative properties (spectra, quantum yields and lifetimes) of ruthenium-polypyridyl complexes are investigated to better understand th...

conditions, their direct radiative effect is mainly determined by coverage and optical depth. The microphysical properties of contrail cirrus likely differ from those of most natural cirrus, at least during the initial stages of the contrail cirrus life cycle (Heymsfield et al. 2010). Contrails form and persist in air that is ice saturated, whereas natural cirrus usually requires high ice super...

We use the radiative transfer model and chemistry transport model to improve our retrievals of dust optical properties from satellite measurements. The optical depth and absorbing optical depth of mineral dust can be obtained from our improved retrieval algorithm. We find the nonsphericity and absorption of dust particles strongly affect the scattering signatures such as phase function and pola...

[1] A multiscale methodology for the determination of the macroscopic optical properties of snow is presented. It consists of solving the coupled volume-averaged radiative transfer equations for two semi-transparent phases – ice and air – by Monte Carlo ray tracing in an infinite slab via direct pore-level simulations on the exact 3D microstructure obtained by computed tomography. The overall r...

We demonstrate in this work that the use of metasurfaces provides a viable strategy to largely tune and enhance near-field radiative heat transfer between extended structures. In particular, using a rigorous coupled wave analysis, we predict that Si-based metasurfaces featuring two-dimensional periodic arrays of holes can exhibit a room-temperature near-field radiative heat conductance much lar...

The estimation of radiative forcing due to desert dust and forest fires aerosols is a very important issue since these particles are very efficient at scattering and absorbing both short and longwave radiation. In this work, the evaluation of the aerosol radiative forcing at the top of the atmosphere over the south of Portugal is made, particularly in 5 the regions ofÉvora and of Cabo da Roca. ...

Thermal surface emissions have now been detected from more than a dozen isolated neutron stars, including radio pulsars, radioquiet neutron stars and magnetars. These detections can potentially provide important information on the interior physics, magnetic fields, and surface composition of neutron stars. Understanding the properties of matter and radiative transfer in strong magnetic fields i...

The atmosphere is often divided into several homogeneous layers in simulations of radiative transfer in plane-parallel media. This artificial stratification introduces discontinuities in the vertical distribution of the inherent optical properties at boundaries between layers, which result in discontinuous radiances and irradiances at layer interfaces, which lead to errors in the radiative tran...