Search results for "Stark"
showing 10 items of 83 documents
Stark effect in some lines of neutral bromine
2002
Abstract This work presents experimental results of profile parameters for prominent lines of neutral bromine, for which serious discrepancies between experimental values of different authors as well as between experimental and calculated values were observed. The observed discrepancies between shock tube and earlier arc experiments are very large. Our results of profile parameters, obtained also in a wall-stabilized arc, show acceptable agreement with the earlier arc measurements. It is obvious, that the shock tube experimental result is out of the range of acceptable inaccuracy and should be remeasured. The theoretical calculations based on different assumptions give also strongly diverge…
Rovibrational spectroscopy of ethylene : Stark effect : Application to ethylene in zeolites
2010
The objective of this report is to present a study as complete as possible of the Stark effect in the asymmetric top molecules of X2Y4 type possessing the D2h symmetry group and to apply it to the problem of the spectroscopy of the ethylene molecule trapped in a zeolite. For the first time, a tensorial formalism adapted to the study of the Stark effect for the O(3) D2h group chain was developed. In parallel, a computer package was worked out as a new generation of software called D2hTDS-ST using a simpler basis, allowing an economy in the calculation time. On the basis of the theoretical and computing tools as well as from the experimental spectra, recorded in the laboratory, we made a firs…
ROVIBRATIONAL AND STARK SPECTROSCOPY OF THE X2Y4MOLECULES. APPLICATION TO ETHYLENE
2005
This thesis is devoted to the spectroscopy of ethylene in the aim of studying the molecule trapped in zeolites. The first part deals with the tensorial model adapted to the symmetry of the isolated molecule: formalism, Hamiltonian and transition moments. To take the strong electric fields existing into zeolites into account, an extension of the model to the Stark effect is proposed in the second part. The third part describes the programs of the D2hTDS software which have been built for the calculation and analysis of X2Y4-type molecule spectra. The fourth part presents applications to the calculation and analysis of zero-field and Stark ethylene spectra. In particular, the model has been t…
Electric field control of the optical properties in magnetic mixed-valence molecules
2014
We propose the use of an electric field stimulus to strongly affect the optical properties of ferromagnetic mixed-valence (MV) dimers. This proposal is based on the prediction of an anomalous Stark effect in the intervalence absorption bands of these multi-electron MV systems. As distinguished from the conventional Stark effect observed in one-electron dimers, a strong change of the intervalence bands accompanies the crossing of the different spin levels caused by the application of an electric field. This new effect can be referred to as giant spin-dependent Stark effect. In spintronics this opens up the possibility for optical detection of the spin state in these magnetic molecules.
Efectos de los campos eléctrico y magnético sobre los estados electrónicos excitados en nanoestructuras cuánticas semiconductoras
2013
Las nanoestructuras cuánticas semiconductoras ofrecen un gran potencial en cuanto al diseño de nuevos materiales con propiedades ópticas novedosas. El confinamiento cuántico y la aplicación de campos eléctrico y magnético externos muestran una riqueza de efectos cuánticos cuya aplicación es en muchos casos desconocida. Es notable al respecto la gran cantidad de comprtamientos no lineales que muestran, por ejemplo, la energía excitónica, los tiempos de recombinación, el efecto túnel y la consiguiente extinción de la señal espectral de fotoluminiscencia en los semiconductores. Lo notable de los modelos, y que queda confirmado por los experimentos es la competición entre tres efectos presentes…
From the spherical top to the asymmetric top
2004
This habilitation report presents a synthesis of my research work during the last 14 years. I have distinguished my experimental activities (part III), my theoretical work on the spectroscopy of quasi-spherical tops (part IV) and that concerning the spectroscopy of molecules trapped in solids (part V).
Työttömän asiakkaan palvelu- ja ohjausmalli terveyden edistämisen työmenetelmänä : hoitajien näkökulma
2008
"Tää on Jumalan synti myyä viinaa" : ravintoloitsijoiden suhtautuminen anniskelun viranomaisvalvontaan
2017
Tämän pro gradu -tutkielman tavoitteena on selvittää ravintola-alan pienyrittäjien suhtautumista anniskelun viranomaisvalvontaan, toisin sanoen alkoholitarkastajiin ja -tarkastuksiin sekä alkoholipolitiikkaan ja -lainsäädäntöön. Tutkielmassa tarkastellaan ravintoloitsijoiden asenteita valvontaa kohtaan, sekä pyritään tunnistamaan ja nimeämään kehyksiä, joiden kautta asennoitumista ilmaistaan. Aineisto on kerätty haastattelemalla kymmentä ravintola-alan yrittäjää neljässä eri kaupungissa neljän eri Aluehallintoviraston vastuualueella niin kutsutun laadullisen asennetutkimuksen tarjoamin keinoin ja menetelmin. Analyysin kohteena ovat ravintoloitsijoiden kuvaukset alkoholitarkastajista ja heid…
Ge quantum well plasmon-enhanced quantum confined Stark effect modulator
2014
ABSTRACTWe theoretically and experimentally investigate a novel modulation concept on silicon (Si) based on the combination of quantum confinement and plasmon enhancement effects. We experimentally study the suitability of Ge/SiGe quantum wells (QWs) on Si as the active material for a plasmon-enhanced optical modulator. We demonstrate that in QW structures absorption and modulation of light with transverse magnetic (TM) polarization are greatly enhanced due to favorable selection rules. Later, we theoretically study the plasmon propagation at the metal-Ge/SiGe QW interface. We design a novel Ge/SiGe QW structure that allows maximized overlap between the plasmonic mode and the underlying Ge/…
Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy
2021
The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…