Spontaneous emission

About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.

Modification of single molecule fluorescence close to a nanostructure: radiation pattern, spontaneous emission and quenching

Abstract: The coupling of nanostructures with emitters opens up ways for the realization of man-made subwavelength light emitting elements. In this article we present an overview of our recent progress in the modification of fluorescence when an emitter is placed close to a nanostructure. In order to control the wealth of parameters that contribute to this process, we have combined scanning probe technology with single molecule microscopy and spectroscopy. We discuss the enhancement and reduction of molecular excitation and emission rates in the presence of a dielectric or metallic nanoparticle and emphasize the role of plasmon resonances in the latter. Furthermore, we examine the spectral and angular emission characteristics of the molecule–particle system. The experimental findings are in excellent semi-quantitative agreement with the outcome of theoretical calculations. We show that the interaction of an emitter with a nanoparticle can be expressed in the framework of an optical nanoantennae and propose arrangem...

Enhanced single-photon emission from quantum dots in photonic crystal waveguides and nanocavities.

Abstract: A theoretical formalism is presented to investigate enhanced radiative decay of excited dipoles in photonic crystal waveguides and nanocavities with a view to achieving efficient single-photon emission from embedded quantum dots. Surprisingly, large enhancement effects are achievable in both waveguides and nanocavities, and enhanced emission in the waveguide is shown to scale proportionally (inversely) with the photon group index (velocity). Further, a way to include radiative coupling of the quantum dot is shown, and the importance of its inclusion is subsequently demonstrated.

Limit of Doppler cooling

Abstract: We present a quantum theory of one-dimensional laser cooling of free atoms using a transition with a J = 0 ground state and a J = 1 excited state. This treatment is valid both for broad lines (recoil energy small compared with the energy width ℏ Γ of the excited level) and for narrow lines. For broad lines we recover the well-known cooling limit for a two-level transition (∼ℏΓ/2), whereas for a narrow line the cooling limit is found to be of the order of the recoil energy. The stationary momentum distribution is obtained for both cases and is found to be close to the one obtained by Monte Carlo simulations.

The emission and absorption of waves by charged particles in magnetized plasmas

Abstract: A semiclassical theory describing the emission and absorption of waves is applied to the interaction of charged particles with waves in magnetized plasmas. Spontaneous emission of all cold plasma wave modes is calculated in detail. The method gives the absorption coefficient for the waves and a diffusion equation in momentum space for the particles describing the effects of the induced processes.

Luminescence and thermal behaviors of free and trapped excitons in cesium lead halide perovskite nanosheets

Abstract: Very recently, all-inorganic perovskite CsPbX3 (X = Cl, Br, I) nanostructures such as nanoparticles, nanoplates, and nanorods have been extensively explored. These CsPbX3 nanostructures exhibit excellent optical properties; however, the photophysics involved is not yet clear. Herein, the emission properties and luminescence mechanism of CsPbBr3 nanosheets (NSs) were investigated using steady-state and time-resolved photoluminescence (PL) spectroscopic techniques. Moreover, two kinds of excitonic emissions (Peak 1 and Peak 2) are observed at low temperatures (<80 K) under the conditions of low excitation level. They are revealed to stem from the radiative recombination of trapped and free excitons by examining their spectral features and emission intensity dependences on excitation power. Thermally induced exchange between the two kinds of excitons is found and modeled quantitatively; this has led to the determination of an activation energy of 13 meV. Thermal redistribution of trapped excitons and thermal expansion-induced blueshift of the bandgap are jointly responsible for the abnormal temperature dependence of the position of Peak 1, whereas the latter is predominant for the monotonic blueshift of the position of Peak 2 with an increase in temperature. These results and findings shed some light on the complicated luminescence mechanism of CsPbBr3 NSs.