Characteristics of radiative and non-radiative energy fluxes over monsoon trough zone

In order to describe behaviour of radiative and non-radiative erergy fluxes in the surface layer, computation of net radiation, sensible, latent and heat soil flux has been done using hourly global radiation, slow response data of MONTBLEX-90 and surface observation of Varanasi and Jodhpur during rainy and non-rainy days in July 1990. Daily and hourly ground temperature is calculated solving one dimensional heat conduction equation and soil heat flux is computed using force restored method .Outgoing Longwave Radiation (OLR) is calculated by Stefan-Boltzrnann law of radiation and the largest diurnal variability was found over dry convective zone. Results show that OLR from the ground lies in the range 473.0-537.6 Wm-2 at Jodhpur and 497.4 -548.4 Wm-2 at Varanasi during generally cloudy day. The dip in OLR is increascd by 10% with increase of relative humidity and cloudiness. Daily mean of the largest downward soil heat flux are found as 206.4 and 269.4 Wm-2 at Varanasi and Jodhpur respectively during cloudy day. About 40-50% of net radiation is imparted to soil heat flux at Varanasi and Jodhpur. Sum of the hourly non- radiative energy fluxes has not been balanced by net radiation while daily cumulative value of the fluxes balances the net radiation during non-rainy day.

Motion-induced energy shifts of a multilevel atom in a black-body radiation field

We investigate the influence of atomic uniform motion on radiative energy shifts of a multilevel atom when it interacts with black-body radiation. Our analysis reveals that the atomic energy shifts depend crucially on three factors: the temperature of black-body thermal radiation, atomic velocity, and atomic polarizability. In the low-temperature limit, the presence of atomic uniform motion always enhances the effect of the thermal field on the atomic energy shifts. However, in the high-temperature limit, the atomic uniform motion enhances the effect of the thermal field for an atom polarizable perpendicular to the atomic velocity but weakens it for an atom polarizable parallel to the atomic velocity. Our work indicates that the physical properties of atom–field coupling systems can in principle be regulated and controlled by the combined action of the thermal field and the atomic uniform motion.

Спектрально-люминесцентные свойства кристаллов ZrO-=SUB=-2-=/SUB=--Sc-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=--Tb-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

Crystals of the concentration series ZrO2- (8-10) mol.% Sc2O3- (1-2) mol.% Tb2O3 were grown by the method of directional crystallization of the melt from a cold container. Analysis of the spectral-luminescence characteristics of these crystals after growth and after annealing processing in a vacuum revealed the presence of both Tb3 + and Tb4 + ions in them. In crystals ZrO2- (8-10) mol.% Sc2O3- (1-2) mol.% Tb2O3, the presence of a process of non-radiative energy transfer from Tb4 + ions to Tb3 + ions was revealed.

Chromophoric Dendrimer-Based Materials: An Overview of Holistic-Integrated Molecular Systems for Fluorescence Resonance Energy Transfer (FRET) Phenomenon

Dendrimers (from the Greek dendrosàtree; merosà part) are macromolecules with well-defined three-dimensional and tree-like structures. Remarkably, this hyperbranched architecture is one of the most ubiquitous, prolific, and recognizable natural patterns observed in nature. The rational design and the synthesis of highly functionalized architectures have been motivated by the need to mimic synthetic and natural-light-induced energy processes. Dendrimers offer an attractive material scaffold to generate innovative, technological, and functional materials because they provide a high amount of peripherally functional groups and void nanoreservoirs. Therefore, dendrimers emerge as excellent candidates since they can play a highly relevant role as unimolecular reactors at the nanoscale, acting as versatile and sophisticated entities. In particular, they can play a key role in the properties of light-energy harvesting and non-radiative energy transfer, allowing them to function as a whole unit. Remarkably, it is possible to promote the occurrence of the FRET phenomenon to concentrate the absorbed energy in photoactive centers. Finally, we think an in-depth understanding of this mechanism allows for diverse and prolific technological applications, such as imaging, biomedical therapy, and the conversion and storage of light energy, among others.

Highly luminescent hetero-ligand MOF nanocrystals with engineered massive Stokes shift for photonic applications.

A high efficiency emission with a massive Stokes shift is obtained by fluorescent conjugated acene building blocks arranged in nanocrystals. The two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating highly crystalline hetero-MOF nanoparticles The fast diffusion of singlet molecular excitons in the framework, coupled with the fine matching of ligands absorption and emission properties, enables to achieve an ultrafast activation of the low energy emission by diffusion-mediated non-radiative energy transfer in the 100 ps time scale, by using a low amount of co-ligands. This allow to obtain MOF nanocrystals with a fluorescence quantum efficiency of ̴ 70% and an actual Stokes shift as large as 750 meV. This large Stokes shift suppresses the reabsorption of fast emission issues in bulk devices, pivotal for a plethora of applications in photonics and photon managing spacing from solar technologies, imaging, and detection of high energy radiation. These features allowed to realize a prototypal fast nanocomposite scintillator that shows an enhanced performance with respect to the homo-ligand nanocrystals, achieving benchmark. values which compete with those of some inorganic and organic commercial systems.

Effective Hamiltonians in Nonrelativistic Quantum Electrodynamics

In this paper, we consider some second-order effective Hamiltonians describing the interaction of the quantum electromagnetic field with atoms or molecules in the nonrelativistic limit. Our procedure is valid only for off-energy-shell processes, specifically virtual processes such as those relevant for ground-state energy shifts and dispersion van der Waals and Casimir-Polder interactions, while on-energy-shell processes are excluded. These effective Hamiltonians allow for a considerable simplification of the calculation of radiative energy shifts, dispersion, and Casimir-Polder interactions, including in the presence of boundary conditions. They can also provide clear physical insights into the processes involved. We clarify that the form of the effective Hamiltonian depends on the field states considered, and consequently different expressions can be obtained, each of them with a well-defined range of validity and possible applications. We also apply our results to some specific cases, mainly the Lamb shift, the Casimir-Polder atom-surface interaction, and the dispersion interactions between atoms, molecules, or, in general, polarizable bodies.

Impact of radiation absorption on Caputo fractional fluid flow over an exponentially accelerated plate

With the advancement of nuclear energy as one of the top clean energy sources, studies on radiation effects are becoming more popular. Radiation absorption is an exothermic phenomenon where radiative energy is released to the surrounding environment. This occurrence can be seen widely in the field of manufacturing, biology, medicine and fluid mechanics. In this study, the impact of radiation absorption of fluid flow over a vertical plate that is exponentially accelerating will be investigated. Heat and mass transfer flowing vertically over the