Letteratura scientifica selezionata sul tema "Electronic spectroscopies"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Electronic spectroscopies".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Articoli di riviste sul tema "Electronic spectroscopies":

1

KOBAYASHI, NAGAO. "Theoretical interpretation of spectroscopic data". Journal of Porphyrins and Phthalocyanines 04, n. 04 (giugno 2000): 377–79. http://dx.doi.org/10.1002/(sici)1099-1409(200006/07)4:4<377::aid-jpp236>3.0.co;2-3.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
This paper provides a short, representative summary of recent progress in the electronic absorption, magnetic and natural circular dichroism, fluorescence and phosphorescence emission, and IR and Raman vibrational spectroscopies of porphyrine and phthalocyanine compounds. These spectroscopies are discussed in the microsymposium entitled ‘Theoretical Interpretation of Spectroscopic Data’.
2

Oliver, Thomas A. A. "Recent advances in multidimensional ultrafast spectroscopy". Royal Society Open Science 5, n. 1 (gennaio 2018): 171425. http://dx.doi.org/10.1098/rsos.171425.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Multidimensional ultrafast spectroscopies are one of the premier tools to investigate condensed phase dynamics of biological, chemical and functional nanomaterial systems. As they reach maturity, the variety of frequency domains that can be explored has vastly increased, with experimental techniques capable of correlating excitation and emission frequencies from the terahertz through to the ultraviolet. Some of the most recent innovations also include extreme cross-peak spectroscopies that directly correlate the dynamics of electronic and vibrational states. This review article summarizes the key technological advances that have permitted these recent advances, and the insights gained from new multidimensional spectroscopic probes.
3

Dessau, Dan, Zahid Hussain e Z. Q. Qiu. "Workshop on Spectroscopies of Electronic Materials". Synchrotron Radiation News 15, n. 1 (gennaio 2002): 13–14. http://dx.doi.org/10.1080/08940880208602925.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
4

Busca, G., G. Martra e A. Zecchina. "Characterisation by vibrational and electronic spectroscopies". Catalysis Today 56, n. 4 (marzo 2000): 361–70. http://dx.doi.org/10.1016/s0920-5861(99)00296-5.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Biswas, Somnath, JunWoo Kim, Xinzi Zhang e Gregory D. Scholes. "Coherent Two-Dimensional and Broadband Electronic Spectroscopies". Chemical Reviews 122, n. 3 (17 gennaio 2022): 4257–321. http://dx.doi.org/10.1021/acs.chemrev.1c00623.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
6

Pen, H. F., M. Abbate, A. Fuijmori, Y. Tokura, H. Eisaki, S. Uchida e G. A. Sawatzky. "Electronic structure ofY1−xCaxVO3studied by high-energy spectroscopies". Physical Review B 59, n. 11 (15 marzo 1999): 7422–32. http://dx.doi.org/10.1103/physrevb.59.7422.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
7

Fujisawa, M., S. Suga, T. Mizokawa, A. Fujimori e K. Sato. "Electronic structures ofCuFeS2andCuAl0.9Fe0.1S2studied by electron and optical spectroscopies". Physical Review B 49, n. 11 (15 marzo 1994): 7155–64. http://dx.doi.org/10.1103/physrevb.49.7155.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
8

Le F�vre, P., H. Magnan, K. Hricovini, D. Chandesris, J. Vogel, V. Formoso, T. Eickhoff e W. Drube. "Ce Electronic Structure Studied by Resonant Electron Spectroscopies". physica status solidi (b) 215, n. 1 (settembre 1999): 617–23. http://dx.doi.org/10.1002/(sici)1521-3951(199909)215:1<617::aid-pssb617>3.0.co;2-c.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
9

Hawrylak, P., A. Wojs, D. J. Lockwood, P. D. Wang, C. M. Sotomayor Torres, A. Pinczuk e B. S. Dennis. "Optical spectroscopies of electronic excitations in quantum dots". Surface Science 361-362 (luglio 1996): 774–77. http://dx.doi.org/10.1016/0039-6028(96)00531-6.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
10

Khalifi, Mohammed El, Fabien Picaud e Mohamed Bizi. "Electronic and optical properties of CeO2 from first principles calculations". Analytical Methods 8, n. 25 (2016): 5045–52. http://dx.doi.org/10.1039/c6ay00374e.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Electronic spectroscopies":

1

Li, Xin. "Theoretical studies on electronic structure and x-ray spectroscopies of 2D materials". Doctoral thesis, KTH, Teoretisk kemi och biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185683.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Extraordinary chemical and physical properties have been discovered from the studies of two-dimensional (2D) materials, ever since the successful exfoliation of graphene, the first 2D material. Theoretical investigations of electronic structure and spectroscopies of these materials play a fundamental role in deep understanding the various properties. In particular, the band structure and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy can provide critical information near the Fermi level. In this thesis, we performed first-principles density functional theory calculations to study the electronic structure and NEXAFS spectra of four materials, including three 2D materials and one bulk material. The three 2D materials are atomically thin bismuth telluride, nitrogen and boron nitride doped graphenes. The bulk material is lithium intercalated graphite, an analogue of lithium doped graphene. Our studies provide important electronic property information of the studied materials, and are helpful for understanding their properties and developing potential applications.

QC 20160425

2

Lindblad, Andreas. "A Treatise on the Geometric and Electronic Structure of Clusters : Investigated by Synchrotron Radiation Based Electron Spectroscopies". Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8463.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):

Clusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (i.e. nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.

The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.

Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.

Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger vis-à-vis Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.

Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.

3

Lee, Min-I. "Atomic structure, electronic states and relaxation dynamics in photovoltaic materials and interfaces from photoemission-related spectroscopies". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS220/document.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
L'efficacité du processus photovoltaïque dépend du matériau actif à travers la structure de bande et la dynamique des porteurs de charge. Dans cette thèse, nous avons relié les propriétés électroniques et la dynamique de relaxation à la structure atomique des matériaux utilisés pour deux technologies différentes de cellules solaires, celle à base d’hétérostructures de silicium, et celle à base de pérovskites hybrides organiques-inorganiques. Dans les cellules solaires de silicium, nous avons analysé l'influence des défauts sur les propriétés électroniques des hétérostructures de silicium amorphe (a-Si:H/a-SIC:H/c-Si) par spectroscopies des niveaux de coeur et de la bande de valence. En particulier, nous avons quantifié le nombre de liaisons pendantes induites dans la couche a-Si:H par irradiation, et nous avons identifié les états électroniques qui leur sont associés. Enfin nous avons expliqué les transitions précédemment observées par photoluminescence. Dans les cellules solaires à pérovskite hybride, nous avons corrélé la structure atomique, la structure électronique et la dynamique électronique pour des pérovskites bi- et tridimensionnelles. Dans ce but nous avons utilisé tout un panel de techniques complémentaires: diffraction des rayons X, spectroscopie de photoémission résolue en angle, spectroscopie de photoémission inverse et photoémission à deux photons résolue en temps. Pour la pérovskite bidimensionnelle (C₆H₅C₂H₄NH₃)₂PbI₄, nous avons déterminé expérimentalement les bandes de valence et de conduction et nous les avons comparées aux simulations de la fonction spectrale. Pour la pérovskite tridimensionnelle CH₃NH₃PbI₃, nous avons aussi déterminé les structures de bande expérimentale et simulée. Des signatures spectrales très larges ont été observées expérimentalement, ce qui relaxe les conditions de transition optique avec un impact éventuel sur l'efficacité des cellules solaires. Tant dans les expériences que dans les calculs, nous observons que le poids spectral suit une périodicité cubique alors que le système est structurellement dans une phase tétragonale. Cette contradiction apparente s'explique par la largeur spectrale des bandes, qui cache le repliement dû à la distorsion tétragonale. En ce qui concerne la dynamique de relaxation, nous avons observé que les porteurs photoexcités se thermalisent dans une échelle de temps subpicoseconde par couplage aux vibrations des cations organiques. À des échelles de temps plus longues (10~100 picosecondes), la diffusion électronique contrôle la dynamique. Cette dynamique est affectée par les défauts induits par recuit, qui localisent les électrons photoexcités pendant plus de 300 picosecondes
The efficiency of the photovoltaic process depends on the electronic band structure of the active material and the charge carrier dynamics. In this thesis, we have studied how these issues are related to the atomic structure in materials for two different technologies of solar cells, namely silicon heterostructure solar cells, and hybrid organic-inorganic perovskite solar cells. In silicon heterostructure solar cells, we have analyzed the impact of defects on the electronic properties of amorphous silicon heterostructures (a-Si:H/a-SIC:H/c-Si) by core level and valence band spectroscopies. In particular, we have quantified the number of dangling bonds inside a-Si:H layer upon irradiation, we have identified the electronic states associated to them, and we have understood the transitions previously observed by photoluminescence. In perovskite solar cells, we have correlated the atomic structure, the electronic structure and the electronic dynamics for two- and three-dimensional hybrid organic-inorganic perovskites. We have used with this goal a whole panel of complementary techniques: X-ray diffraction, angle-resolved photoemission spectroscopy, inverse photoemission spectroscopy, and time-resolved two-photon photoemission. In the two-dimensional perovskite (C₆H₅C₂H₄NH₃)₂PbI₄, the valence and conduction bands have been determined experimentally and compared to spectral function simulations. In the three-dimensional perovskite CH₃NH₃PbI₃, we have again determined the band structure and simulated it. Very broad spectral features have been experimentally observed, which relax the optical transition conditions impacting in the solarcell efficiencies. In both experiments and calculations, we observe that the spectral weight follows a cubic periodicity while the system is structurally in the tetragonal phase. This apparent contradiction is explained by the band broadness, which hides the band folding of the tetragonal distortion. As for the relaxation dynamics, we have observed that the photoexcited carriers thermalize in a subpicosecond time scale through the coupling to organic cation vibrations. At longer timescales (10~100 picoseconds), the electron diffusion controls the dynamics. This dynamics is affected by the annealing-induced defects, which localize the photoexcited electrons for more than 300 picoseconds
4

Carleschi, Emanuela. "Electronic structure of transition metal and rare earth ions in complex materials by resonant core-level spectroscopies". Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3061.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
2007/2008
In the course of this thesis I present an experimental investigation into various strongly correlated transition metal and rare earth compounds using core-level spectroscopic techniques, which have augmented the understanding of the electronic properties of these different systems. I will discuss the orbital occupation and the symmetry of the states near the Fermi level, responsible for the variety of ground states shown by a variety of strongly correlated systems such as misfit cobaltates, strontium ruthenates, metallic manganese and rare earth compounds.
XXI Ciclo
1978
5

Tournier-Colletta, Cédric. "Etude par spectroscopies d'électrons d'interfaces métalliques et semiconductrices". Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10109/document.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Cette thèse présente une étude des propriétés électroniques de systèmes de basse dimension à base de métaux et de semiconducteurs. La première partie de l'étude traite le confinement de l'état de Shockley dans des nanostructures tridimensionnelles d'Ag(111), par des mesures STM/STS à très basse température (5 K). Nous avons d'abord analysé en détail la structure en énergie et la distribution spatiale des modes confinés. Nous avons ensuite mis à profit la nature discrète du spectre en énergie pour étudier le temps de vie des quasiparticules. Un comportement typique de liquide de Fermi est mis en évidence, et nous montrons que le mécanisme de diffusion dominant est associé au couplage électron-phonon. La contribution extrinsèque provenant du confinement partiel de l'onde électronique a également été obtenue. Une loi d'échelle est observée avec la taille des nanostructures, ce qui permet d'extraire un coefficient de réflexion plus important que dans de simples ilôts monoatomiques. La seconde partie de l'étude est consacrée aux couches ultra-minces semiconductrices obtenues par dépôts d'alcalins (K, Rb, Cs) sur la surface Si(111):B-[racine]3. Ce travail résout la controverse concernant la nature de l'état fondamental de ce système, et notamment l'origine de la reconstruction 2[racine]3 obtenue à la saturation du taux de couverture. La compréhension en amont de la structure cristallographique permet d'élucider les propriétés électroniques. Nous montrons qu'une approche à un électron, conduisant à un isolant de bandes, décrit le système de manière convaincante, malgré l'indication de forts effets polaroniques. Ce résultat est le fruit d'une étude approfondie combinant des techniques diverses et complémentaires (LEED, ARPES, XPS, STM/STS et calcul DFT)
This thesis is devoted to the electronic properties of low-dimensional systems based on metal and semiconducting materials. The first part deals with the Shockley state confinement in Ag(111) nanostructures, by means of very-low temperature (5 K) STM/STS measurements. We study the electronic structure and spatial distribution of the confined modes. Then the discrete nature of the electronic spectrum allows one to yield the quasiparticule lifetime. A Fermi-liquid behaviour is evidenced and we show that the dominant decay mechanism is attributed to the electron-phonon coupling. The extrinsic contribution arising from the partial confinement of the electronic wave is obtained as well. A scaling law with the nanostructure width is demonstrated, from which we deduce a higher reflection amplitude than in monoatomic islands. In the second part of the thesis, we study semiconducting ultra-thin films produced by alkali (K, Rb, Cs) deposition on the Si(111):B-[root of]3 surface. This work solves the controversy concerning the ground state of this system, and especially the nature of the 2[root of]3 surface recontruction obtained at saturation coverage. Prior understanding of the crystallographic structure allows to elucidate the electronic properties. We show that a one-electron picture, leading to a band insulator scenario, gives a good description of the system, in spite of strong polaronic effects. This conclusion results from an in-depth, combined study of complementary techniques (LEED, ARPES, XPS, STM/STS and DFT calculations)
6

Capogrosso, Valentina. "Dimensionality and ordering effects on the electronic structure of low dimensional strongly correlated electron transition metal oxides". Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8587.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
2011/2012
Nel vasto scenario dei materiali fortemente correlati gli ossidi dei metalli di transizione hanno attratto enorme interesse a causa delle loro interessanti proprietà fisiche, come ad esempio, la superconduttività nei cuprati e la magnetoresistenza gigante nelle manganiti. In particolare, il mio interesse è stato rivolto ad una specifica classe di materiali, per i quali la dimensionalità è il parametro più importante. Le attività sperimentali sono state focalizzate verso due sistemi: la manganite Pr0.5Ca1.5MnO4 dopata a metà e a strato singolo (hd-PCMO) e la famiglia dei rutenati Srn+1RunO3n+1 (n=1,2,3). Entrambi questi sistemi esibiscono fenomeni affascinanti strettamente legati ad una complicata interazione tra i gradi di libertà del reticolo cristallino, di spin, di carica, ed orbitale, dove la dimensionalità cristallina gioca un ruolo cruciale. Con il mio progetto di dottorato ho studiato alcune proprietà dei materiali sopracitati per mezzo di spettroscopie con raggi X, come l’emissione risonante di raggi X (RXES) e l’assorbimento di raggi X (XAS) statico e risolto in tempo. Tutte le misure sono state condotte utilizzando la linea di luce BACH (linea di luce per dicroismo avanzato) dell’anello di accumulazione Elettra della Elettra-Sincrotrone Trieste. Il sistema hd-PCMO presenta una transizione di ordinamento di carica ed orbitale (CO-O) ad una temperatura TCO relativamente elevate, i.e. 340 K, accompagnata da una distorsione strutturale ortorombica, dove i portatori di carica fortemente correlati eg del Mn si ordinano in sotto-reticoli cristallografici separati (stato di carica ordinato) con un carattere orbitale specifico (stato di ordinamento orbitale). Inoltre, hd-PCMO presenta anche una risposta reticolare anomala ad una temperatura 20 K sopra la temperatura di Neél TN, che è associata ad un inatteso accoppiamento spin-reticolo. Poiché mancava uno studio degli stati elettronici non occupati del PCMO, misure dipendenti dalla temperatura per mezzo del dicroismo lineare (XLD) sono state realizzate alle soglie K dell’ossigeno e L3 del Mn al fine di spiegare il ruolo della topologia orbitale dei Mn 3d – O 2p. I dati sperimentali, supportati da calcoli ab-initio LDA+U, ci danno informazioni sulla ridistribuzione di carica e sui cambiamenti delle p-DOS alla transizione CO-O e a quella antiferromagnetica (AFM). I risultati ottenuti mostrano che l’interazione competitiva tra la distorsione locale atomica, necessaria per permettere l’ordinamento CO, e le dinamiche di carica del meccanismo di hopping regolano lo stato orbitale dei portatori di carica. Inoltre, sulla base di studi teorici che predicono la formazione di fasi orbitali e strutturali transienti “nascoste” per mezzo della stimolazione ottica, abbiamo studiato le DOS non occupate dello stato metastabile indotto otticamente nel PCMO per mezzo della XAS risolta in tempo, che offre uno strumento unico per misurare le DOS proiettate in sito ed in simmetria degli stati metastabili della materia. Le misure XAS risolte in tempo alla soglia K dell’ossigeno sono state realizzate per mezzo di un nuovo apparato sperimentale disponibile a BACH, che si basa su un laser Ti:zaffiro (impulsi di pompa) con tasso di ripetizione variabile sincronizzato con gli impulsi a 500 MHz dei raggi X (impulsi di sonda). L’evoluzione temporale degli spettri XAS attraverso la transizione CO-O fotoindotta otticamente risulta differente rispetto alle misure XAS adiabatiche, dimostrando l’esistenza di una “fase nascosta” fotoindotta nel PCMO, la cui natura è ancora sconosciuta. I rutenati Srn+1RunO3n+1 (n=1,2,3) sono emersi come una famiglia importante di peroschiti a causa dell’evoluzione inattesa e senza precedenti dal comportamento anisotropico ferro- o metamagnetico del Sr4Ru3O10 (n=3) dipendente dalla direzione del campo magnetico, all’ aumentato paramagnetismo di Pauli vicino all’ordinamento magnetico del Sr3Ru2O7 (n=2) e, infine, alla superconduttività a bassa temperature in Sr2RuO4 (n=1). Nonostante vengano riportati numerosi studi sulle proprietà strutturali e magnetiche di questi composti, l’evoluzione delle strutture elettroniche occupate e non occupate non è stata investigata in dettaglio. Quindi, la dipendenza delle strutture elettroniche e l’ibridizzazione degli stati 2p dell’ossigeno sono state investigate combinando la spettroscopia XAS alla soglia K dell’ossigeno (transizione 2p-1s) dipendente dalla polarizzazione e la spettroscopia RXES. Una sezione del capitolo 3 è dedicata ad illustrare un setup sperimentale sviluppato recentemente per esperimenti XAS risolti in tempo sfruttando la struttura temporale “multibunch” dell’anello di accumulazione del sincrotrone. Sfruttando le potenzialità di questo setup, la transizione di superficie semiconduttore-metallo nel germanio cristallino è stata fotoindotta ed il set completo di dati viene discusso. Lo schema della mia tesi di dottorato è il seguente. Il primo capitolo presenta una panoramica dell’intero lavoro. Il secondo capitolo è diviso in due sezioni. La prima sezione introduce il lettore alla fisica orbitale ed alle transizioni di fase elettroniche nei metalli di transizione a ridotta dimensionalità, con un excursus sullo stato dell’arte dei composti 3d del manganese e la famiglia 4d dei rutenati. L’intento della seconda sezione è quello di spiegare l’importanza delle tecniche spettroscopiche nei raggi X molli come strumenti per investigare le proprietà elettroniche dei solidi. La descrizione delle spettroscopie XAS e RXES vengono riviste più in dettaglio nel capitolo 3, che include anche la descrizione dell’apparato sperimentale della beamline BACH e del laboratorio T-ReX al Sincrotrone Elettra. Il capitolo 4 è dedicato alla teoria funzionale di densità (DFT) ed alla approssimazione locale di densità più U (LDA+U) ed ai dettagli del modello del sistema hd-PCMO. Il capitolo 5, che presenta i casi studiati, è diviso in due sezioni: il caso del PCMO, che include le misure XAS statiche e risolte in tempo, ed il caso della serie Ruddlesden-Popper dei rutenati di Sr investigate per mezzo della RXES. Nel capitolo finale vengono presentati i commenti finali su questo lavoro.
In the vast scenario of strongly correlated-electron materials transition-metal oxides have attracted enormous interest because of their interesting physical properties, including for example, superconductivity in cuprates and colossal magnetoresistance in manganites. In particular, my interest was directed to a particular class of materials, whose dimensionality is the most defining material parameter. With my Ph.D. project I deepened into some physical properties of these materials by means of core-levels spectroscopies such as resonant x ray emission (RXES) and static and time-resolved x ray absorption (XAS). All the measurements have been carried out at the beamline BACH (Beamline for Advanced diCHroism) at the Elettra light source facility in Trieste. The experimental activities focused on two case-study systems: the single layered half-doped Pr0.5Ca1.5MnO4 (hd-PCMO) and the layered Srn+1RunO3n+1 (n=1,2,3) family. Both these systems exhibit fascinating phenomena intimately related to a complicated interplay between the crystal lattice, spin, charge, and orbital degrees of freedom, where crystal dimensionality plays a crucial role. hd-PCMO exhibits a charge-orbital ordering (CO-O) transition at a remarkably high TCO, slightly above room temperature, accompanied by an orthorhombic structural distortion, where the strongly correlated Mn eg charge carriers order onto separate crystallographic sub-lattices (charge-ordered state) with a specific orbital character (orbital ordered state). Furthermore, hd-PCMO also displays an anomalous lattice response at temperatures 20K above the Neél temperature TN, which is associated to an unexpected spin-lattice coupling. Since a study of the PCMO unoccupied electronic states was lacking, temperature dependence measurements by XAS linear dichroism (XLD) have been performed at the O-K and Mn-L3 thresholds in order to elucidate the role of Mn 3d - O 2p orbital topology. The experimental data, supported by ab-initio LDA+U, shed light on the charge redistribution and p-DOS changes at the CO-O and antiferromagnetic (AFM) transitions. The results obtained show that the competitive interplay between the local atomic distortion, necessary for accomodating the CO-ordering, and the charge dynamics of the hopping mechanism regulates the orbital state of the charge carriers. Furthermore, on the basis of theoretical studies that predict the formation of transient “hidden” orbital and structural phases by optical stimulation, we have studied the unoccupied DOS of the optically induced metastable state in PCMO by means of time resolved XAS, which offers a unique tool to measure site and symmetry projected DOS of metastable states in matter. Tr-XAS measurements at the O-K edge have been carried out by means of a novel experimental apparatus available at BACH, which is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ∼ 500 MHz X-ray photon pulses (probe pulses). The time evolution of the XAS lineshapes across the optically photoinduced CO-O transition results different respect to the adiabatic XAS measurements, demonstrating the existence of a photoinduced “hidden phase” in PCMO, whose nature is still unknown. The layered Srn+1RunO3n+1 (n=1,2,3) have emerged as an important family of perovskites because of the unexpected and unprecedented evolution from anisotropic ferro- or metamagnetic behavior of Sr4Ru3O10 (n=3) dependent on the direction of the magnetic field, enhanced Pauli paramagnetism close to magnetic order of Sr3Ru2O7 (n=2) and, finally, to low-temperature superconductivity in Sr2RuO4 (n=1). Although numerous studies have been reported on the structural and magnetic properties of these compounds, the evolution of the occupied and unoccupied electronic structures were not investigated in detail. Thus, the dependence of electronic structures and the hybridization of O 2p states have been investigated by combining polarization dependent O K (2p-1s transition) XAS and RXES spectroscopies. A section of the chapter 3 is dedicated to illustrate a newly developed experimental setup for time-resolved XAS experiments by exploiting the multibunch time structure of a synchrotron storage ring. By exploiting the capabilities of this setup, the surface semiconductor-metal transition in crystalline germanium has been photoinduced and the complete set of data discussed. The outline of my Ph.D. thesis is the following. The first chapter presents an overview of the entire work. The second chapter is divided into two sections. The first section introduces the reader into the orbital physics and the electronic phase transitions in low dimensional transition metal oxides, with an excursus on the state of the art of 3d manganese compounds and the family of 4d Ruthenates. The second section is aimed to explain the importance of soft x-ray spectroscopic techniques as tools to investigate the electronic properties of solids. The description of XAS and RXES are reviewed in more details in chapter 3, which includes also the description of the experimental apparatus of BACH beamline and T-ReX lab at the Elettra synchrotron light source. Chapter 4 is dedicated to the Density Functional Theory (DFT) and Local Density Approximation plus U (LDA+U) theories and to the details of the modelling of the hd-PCMO system. Chapter 5, which presents the cases studied, is divided into two sections: the case of PCMO, including static and time resolved XAS measurements, and the case of Ruddlesden-Popper series of Sr Ruthenates investigated by means of RXES. In the final chapter the concluding remarks on this work are presented.
XXV Ciclo
1983
7

Gallo, Erik. "Modification of the electronic structure of catalytic active transition-metal centers upon molecular adsorption : an XAS/XES study". Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S054/document.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Le travail de thèse "Modification of the electronic structure of catalytic active metal centres upon adsorption of molecules : a XAS and XES study" porte sur l'étude de la structure électronique des métaux de transition utilisés dans les catalyseurs par les techniques spectroscopiques d'absorption et d'émission de rayons durs (rayonnement synchrotron). Il s'agit, en particulier, d'utiliser les avancées dans les techniques spectroscopiques des rayons X pour l'étude des matériaux nanostructurés en conditions in situ. Le premier chapitre de la thèse, "X-Ray Spectroscopy: an Overview", présente brièvement les techniques spectroscopiques disponibles sur la ligne de lumière ID26 de l'Installation Européenne de Rayonnement Synchrotron (en anglais European Synchrotron Radiation Facility (ESRF), Grenoble), où toutes les mesures présentées dans ce travail ont été effectuées. Dans le deuxième chapitre, "Study of the Electronic structure of the Ti-sites in TS-1 using X-ray spectroscopy", est décrite la caractérisation électronique des centres de Ti en TS-1, qui est un important catalyseur, employé dans de nombreuses usines à travers le monde. Nous montrons que la combinaison des techniques spectroscopiques d'absorption et d'émission des rayons avec des calculs de mécanique quantique permet d'obtenir des informations importantes sur la structure électronique des centres de Ti dans des conditions in situ. Le troisième chapitre, “Identification of the Ti-Ligands in a Silica Supported Ziegler-Natta Catalyst by X-Ray Emission Spectroscopy", présente l'étude d'un catalyseur (une variante du catalyseur Ziegler-Natta), qui affiche un degré élevé/important de désordre chimique. L'utilisation de la théorie fonctionnelle de la densité des états (DFT) pour l'interprétation des données expérimentales a permis de développer des modèles possibles pour l'environnement d'un ligand Ti. Le quatrième chapitre, "Observing the dd-Excitations in CPO-27-Ni using Resonant Inelastic X-ray Scattering", conclut la partie principale de la thèse. Il présente un exemple d'utilisation de la diffusion inélastique des rayons X (RIXS) en chimie pour la détermination des excitations du champ cristallin des ions Ni dans l'oxyde de nickel et d'une cage organique autour d'un Ni métallique (CPO-27-Ni). Le chapitre explique brièvement les différentes approches théoriques qui peuvent être utilisées pour l'interprétation des caractéristiques spectrales. De plus, l'adsorption de molécules sonde, comme le CO sur les centres de Ni en CPO-27-Ni, est discutée sur la base des données expérimentales RIXS. Le dernier chapitre synthétise les résultats obtenus et indique des perspectives futures. Enfin, dans les annexes sont reportés les dispositifs expérimentaux développés dans le cadre du travail de thèse pour des mesures résolues en temps, ainsi que le curriculum vitae et les publications du candidat
The purpose of this research project was to apply advanced X-ray based spectroscopic techniques for investigating the electronic structure of transition metals within catalysts and molecular sieves under in-situ conditions. Thus, the first chapter of the thesis, "X-Ray Spectroscopy: an Overview " briefly presents the spectroscopic techniques available at ID26, beamline of the European Synchrotron Radiation Facility (Grenoble) where all the measurements reported in this work have been obtained. In the second chapter, "Study of the Electronic structure of the Ti-sites in TS-1 using hard X-ray spectroscopy", it is reported the electronic characterization of the Ti centres in titanium silicalite-1 (TS-1), that is a relevant catalyst employed in industrial plants worldwide. The chapter shows that the combination of X-ray absorption and X-ray emission spectroscopy with quantum mechanical calculations is effective to obtain important insights on the electronic structure of the Ti-centres under in-situ conditions. The third chapter entitled “Identification of the Ti-Ligands in Silica Supported Ziegler-Natta Catalyst by X- Ray Emission Spectroscopy" presents the study of a variant of the Ziegler-Natta catalyst. The chapter discusses the interpretation of the valence emission lines within the theoretical framework provided by the density functional theory (DFT) and proposes possible models for the Ti-ligand-environment. The fourth chapter, entitled "Observing the dd-Excitations in CPO-27-Ni using Resonant Inelastic X-ray Scattering", concludes the main part of the thesis. It presents the application of resonant inelastic X-ray scattering (RIXS) for obtaining the crystal field excitations of the Ni ions within nickel oxide and within a Ni- metal-organic-framework (CPO-27-Ni). The chapter briefly describes the different theoretical approaches that can be used for the interpretation of the spectral features and discusses the adsorption of probe molecules like H2O, CO and H2S on the Ni centres of CPO-27-Ni. The last chapter (Chapter five) drawn a series of conclusions concerning the performed investigations and indicates possible future research directions. In Appendix A entitled "Pump and Probe Time Resolved Experiments at ID26" it is reported the description of the experimental setup co-developed and co-realized by the candidate for time resolved experiments. The appendix also accounts for the scientific outcome of the performed pump and probe measurements. The curriculum vitae and the publications list of the candidate are respectively reported in Appendix B and C
8

Mahjoub, Mohamed Aymen. "Contributions aux études quantitatives par spectroscopies électroniques (EPES et XPS) : Applications aux surfaces nanostructurées". Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22666/document.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Ce travail porte sur le développement de nouvelles méthodes de caractérisation in-situ basées sur les spectroscopies électroniques XPS et MM-EPES associées à des calculs théoriques obtenus grâce à des simulations Monte-Carlo afin de réaliser des études quantitatives fines et précises. La première partie de ce travail, a été consacrée à l’analyse quantitative de signaux XPS et MM-EPES. Pour cela, dans un premier temps, la fonction de correction de l’analyseur hémisphérique (HSA) qui est une combinaison de l’aire d’analyse (A) et de la transmission (T) a été déterminée en utilisant une nouvelle méthode basée sur des images élastiques. Pour la première fois, la dépendance de A en énergie cinétique des électrons a été mise en évidence. Avec l’utilisation de cette nouvelle fonction, une méthode de caractérisation in situ basée sur la modélisation théorique des signaux XPS et MM-EPES a été développée. Cette méthode a permis d’étudier le dépôt d’un film d’or sur un substrat de silicium oxydé et a montré une grande précision dans le cas de très faibles quantités de matière déposée (< 2 nm) alors que les techniques microscopiques classiques se sont révélées inefficaces. La deuxième partie a porté sur le développement d’une nouvelle technique d’imagerie in-situ appelé MM-EPEM qui consiste à scanner la surface par un faisceau d’électrons et de collecter les électrons rétrodiffusés élastiquement afin de construire une image en intensité de la surface. Les étapes d’obtention des images MM-EPEM et les procédures d’exploitation de ces dernières ont été décrites et optimisées. Ensuite, cette technique a été utilisée pour l’étude de l’état de surface de dépôts d’or sur différents substrats. Cette technique s’avère être non destructive et très sensible aux éléments présents à la surface. Et elle permet de déterminer la cartographie chimique et la nano-organisation de la surface
This thesis focuses on the development of new in-situ methods of characterization based on the electron spectroscopies (XPS and EPES) coupled with theoretical calculations obtained through Monte-Carlo simulations in order to perform very precise quantitative studies. The first part of this thesis was devoted to quantitative studies of XPS and MM-EPES measurements. Firstly, the correction function of a hemispherical analyzer (HSA) which is a combination of the analysis area (A) and the transmission (T) was determined using a new method based on the elastic images. For the first time, the dependence of A on the kinetic energy of electrons was highlighted. Using this function, an in-situ method based on the combination of XPS and MM-EPES modeling was setting up. This method was used to determine the organization of gold film deposed on oxidized silicon substrate. Measurements show that this method is able to determine surface parameters when the microscopy techniques do not give any information in the case of a small quantity of gold deposit (less than 2 nm). The second part of this work was directed towards developing a new generation of microscopy called MM-EPEM which is based on the detection of elastic electrons. The stages required to obtain these images are well described and optimized here. The MM-EPEM images processing was used to study gold growth on different substrates. This technique is a non-destructive method and allows the operator to construct chemical tomography and to determine the nano-organization of the surface
9

Darsey, Gary Paul. "The electronic structure of methyl-substituted ferrocenes and early transition metal bent metallocenes by gas phase ultraviolet and X-ray photoelectron spectroscopies". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184473.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
The details of the electronic structure and bonding in ferrocenes and early transition metal bent metallocenes are probed by photoelectron spectroscopy. The fundamental electronic interaction of the methyl group substituted for a hydrogen on a metal-coordinated cyclopentadienyl ring is shown by a combined core and valence pe spectroscopic study of a series of methyl-substituted ferrocenes. Shifts of core and valence ionization energies upon methyl substitution are equivalent and additive for the iron atom. Knowledge of the core ionization energy shifts for both carbon and iron allow the relative changes in atomic charges upon methyl substitution to be found. In these molecules, the methyl group is found not to be an inductive electron donor as is commonly assumed. The primary electronic effect of methyl substitution is on the valence orbitals of the cyclopentadienyl ring. Methylation of the cyclopentadienyl rings of ferrocene causes a dramatic redistribution of valence electron density and greatly increases the covalent nature of metal-ring bonding. An understanding of the electronic effect of methylation of metal-coordinated cyclopentadienyl rings is used to establish the relative locations of ring π and Cl ionizations in the pe spectra of group IV and V early transition metal bent metallocene dichlorides with both unsubstituted cyclopentadienyl and pentamethylcyclopentadienyl ligands. The differences in chloride and methyl ligand bonding to an early transition metal center are reflected in the photoelectron data of the dichlorides and related dimethyls. The relative differences in metal-chlorine and metal-carbon bond strengths are also shown in the pe data. The relationship between bond strengths and ionization energies is detailed for early transition metal bent metallocenes of niobium and tantalum with a variety of ligands. The relative bond strength/ionization energy information for metal-hydrogen and metal-carbon bonds is shown to help in understanding the stability of niobocene and tantalocene ethylene-hydride complexes and their resistance to intramolecular olefin insertion. Evidence from the pe data concerning the electron distribution as well as the relative bond strengths in these ethylene-hydride complexes is found supporting the consideration of these complexes more properly as metallacyclopropane-hydrides.
10

KELLOGG, GLEN EUGENE. "ELECTRONIC FACTORS OF CARBON - HYDROGEN AND DOUBLE-BONDED CARBON BOND ACTIVATION: EXPERIMENTAL INFORMATION FROM ULTRAVIOLET AND X-RAY PHOTOELECTRON SPECTROSCOPIES (CORE, VALENCE, OLEFIN)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188067.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Principles of transition metal electronic structure are presented to enable an understanding of the activation of C-H and C=C bonds by metals. A multitechnique approach utilizing core and valence photoelectron spectroscopies (p.e.s.) and molecular orbital calculations has been used to gain these insights. In the first half of the dissertation three principles are developed: ligand additivity, core-valence ionization correlation, and ring methylation. In the latter half of the dissertation these principles are seen to be crucial for understanding ionization data for the C-H and C=C activated species. Additive (with respect to ligand substitution) electronic effects, including additive core and valence ionization potentials, are shown in the p.e.s. of phosphine substituted molybdenum carbonyls. These additive effects demonstrate that the electronic effects of ligand substitution are predictable from empirical models. The core-valence ionization correlation enables direct comparison of XPS (core) and UPS (valence) ionization data and allows separation of bonding and overlap induced valence shift effects from Coulombic and relaxation shift effects. In the study of trimethylphosphine substituted cyclopentadienylmanganese tricarbonyl complexes, both the ligand additivity and core-valence ionization correlation principles are less valid than for the molybdenum carbonyl complexes because of loss of the very influential carbonyl backbonding. Methylation of the cyclopentadienyl ring in this system adds another independent variable of electronic structure perturbation and enables separation of the one-center and two-center Coulombic contributions to the core shifts. The above principles are used in the later chapters to show that the initial activation of the C-H bond in alkenylmanganese tricarbonyl complexes is dominated by the interaction of the C-H sigma bonding level with empty metal acceptor levels. The activation stops at the agostic stage rather than proceeding to full β-hydribe abstraction because there is, in these molecules, no gain in the number of pi electrons between the allyl and diene hydride endpoints of the abstraction cycle. Activation of the C=C bond in the cyclopentadienylmetal olefins is similar for Co and Rh complexes despite little similarity in the valence ionization spectra. The spectral differences are largely caused by the relaxation energy differences between Co and Rh. These complexes also provide interesting examples of electron delocalization through the metal. Permethylation of the cyclopentadienyl ring shifts the olefin pi ligand ionizations more than the expected Coulombic shift.

Libri sul tema "Electronic spectroscopies":

1

A, Balzarotti, Guizzetti G e Stella A, a cura di. Highlights on spectroscopies of semiconductors and insulators: Castro Marina, Italy, September 1987. Singapore: World Scientific, 1989.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
2

Wolfgang, Domcke, Yarkony David e Köppel Horst, a cura di. Conical intersections: Electronic structure, dynamics & spectroscopy. River Edge, NJ: World Scientific, 2004.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
3

Hughes, H. P., e H. I. Starnberg. Electron spectroscopies applied to low-dimensional structures. New York: Kluwer Academic, 2002.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
4

M, Loew Leslie, a cura di. Spectroscopic membrane probes. Boca Raton, Fla: CRC Press, 1988.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Baldassare, Di Bartolo, Gambarota Giulio e NATO Advanced Study Institute on Ultrafast Dynamics of Quantum Systems: Physical Processes and Spectroscopic Techniques (1997 : Erice, Italy), a cura di. Ultrafast dynamics of quantum systems: Physical processes and spectroscopic techniques. New York: Plenum Press, 1998.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
6

Nowicki, Marek. Zastosowanie efektów dyfrakcyjnych elektronów pierwotnych i wtórnych w badaniach strukturalnych. Wrocław: Wydawn. Uniwersytetu Wrocławskiego, 2003.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
7

1942-, Thompson Michael, a cura di. Auger electron spectroscopy. New York: Wiley, 1985.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
8

Long, Edward R. Spectroscopic comparison of effects of electron radiation on mechanical properties of two polyimides. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1987.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
9

Uchida, Masaki. Spectroscopic Study on Charge-Spin-Orbital Coupled Phenomena in Mott-Transition Oxides. Tokyo: Springer Japan, 2013.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
10

Scottish, Universities Summer School in Physics (40th 1992 Dundee Scotland). Quantitative microbeam analysis: Proceedings of the Fortieth Scottish Universities Summer School in Physics, Dundee, August 1992. Bristol: The School, 1993.

Cerca il testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri

Capitoli di libri sul tema "Electronic spectroscopies":

1

Colliex, Christian. "Investigation of Local Electronic Properties in Solids by Transmission Electron Energy Loss Spectroscopy". In Core Level Spectroscopies for Magnetic Phenomena, 213–33. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-9871-5_13.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
2

Jentoft, Friederike C. "Electronic Spectroscopy: Ultra Violet-Visible and near IR Spectroscopies". In Characterization of Solid Materials and Heterogeneous Catalysts, 89–147. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527645329.ch3.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
3

Doyen, G., D. Drakova e F. von Trentini. "Theoretical Aspects of Electronic Spectroscopies at (Adsorbate Covered) Surfaces". In Lectures on Surface Science, 154–68. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-71723-9_28.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
4

Zanni, Martin T. "Automated 2D infrared and electronic spectroscopies using pulse shaping". In Springer Series in Chemical Physics, 397–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-95946-5_128.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Jaegermann, Wolfram, Andreas Klein e Christian Pettenkofer. "Electronic Properties of Van Der Waals-Epitaxy Films and Interfaces". In Electron Spectroscopies Applied to Low-Dimensional Materials, 317–402. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/0-306-47126-4_7.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
6

Parmigiani, Fulvio, e Luigi Sangaletti. "Electronic Correlations in the 3s Photoelectron Spectra of the Late Transition Metal Oxides". In Core Level Spectroscopies for Magnetic Phenomena, 249–64. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-9871-5_15.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
7

Smulevich, Giulietta. "Electronic Absorption and Resonance Raman Spectroscopies to Investigate Heme Proteins". In Spectroscopy of Biological Molecules: Modern Trends, 83–84. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5622-6_35.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
8

Mukamel, Shaul, Wei Min Zhang e Vladimir Chemyak. "Structure Determination of Antenna Complexes Using Two-Dimensional Femtosecond Electronic Spectroscopies". In Photosynthesis: Mechanisms and Effects, 3–8. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-3953-3_1.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
9

Sawatzky, G. A. "Electronic Structure of Transition Metal Compounds as Studied by High Energy Spectroscopies". In Springer Series in Solid-State Sciences, 99–124. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83437-0_9.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
10

Conti, Irene, Matteo Bonfanti, Artur Nenov, Ivan Rivalta e Marco Garavelli. "Photo-Active Biological Molecular Materials: From Photoinduced Dynamics to Transient Electronic Spectroscopies". In Challenges and Advances in Computational Chemistry and Physics, 77–142. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57721-6_2.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri

Atti di convegni sul tema "Electronic spectroscopies":

1

Garg, Manish. "Imaging electronic and atomic motion in molecules". In Enhanced Spectroscopies and Nanoimaging 2023, a cura di Prabhat Verma e Yung Doug Suh. SPIE, 2023. http://dx.doi.org/10.1117/12.2677254.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
2

Myers, Anne B., e Alan E. Johnson. "Electronic and Vibrational Dephasing in Solution by Dynamic Symmetry Breaking". In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fe.25.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
All spectroscopies, whether explicitly time-resolved or steady-state, are sensitive to fluctuations in the spectroscopic environment of the chromophore on the time scale of the radiation-matter interaction(s). Simple "two-state jump" models that assume random hopping between just two spectroscopically distinct environments have been well studied. Such models can provide some qualitative insight into the influence of fluctuations on a particular spectroscopy even if the actual system accesses a continuous distribution of states, as is usually the case for chromophores in liquids. The usual two-state models assume that the states differ in their transition frequencies to one or more accessible excited states. In linear spectroscopies, such models predict the well-known coalescence from two discrete resonances to a single broad one which then motionally narrows as the fluctuation rate increases. For multiphoton spectroscopies the effects are more complicated; in particular, for monochromatically excited spontaneous emission, increasing the fluctuation rate causes evolution from a sharp, "resonance Raman-like" spectrum to one having increasing contributions from broad emission.1 The transition frequency fluctuations constitute a source of electronic pure dephasing at the level of the chromophore's density matrix, generating a "fluorescence" component to the emission.
3

Canel, E. "Theoretical Models for Photochromic Systems". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.wd45.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Photo induced spectral changes of some molecules containing electronic π systems are investigated and the effect of electrocyclic reactions (ring closure etc) on their electronic structure is considered. Two types of molecules are studied 1) Molecules which exhibit two stable states characterized by different π electron configurations1) such as 2) electron transfer systems containing a "π electron bridge" linking donor and acceptor which can be modified by a photo induced reaction for example Static electronic π systems are described by a nearest neighbor Huckel Theory, i.e. by a Hamiltonian of the type where ai+, ai are the usual Fermion creation and destruction operators, ε the p electron energy and Γij the coupling between nearest neighbor p orbitals. Due to rotation of molecular fragments Γij depends on the orientation of the relevant p orbitals.
4

Ikeda, Katsuyoshi. "Surface-enhanced Raman spectroscopy at electrified interfaces: electronic SERS and low-frequency vibrational SERS (Conference Presentation)". In Enhanced Spectroscopies and Nanoimaging 2022, a cura di Prabhat Verma e Yung Doug Suh. SPIE, 2022. http://dx.doi.org/10.1117/12.2634191.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Bawendi, Moungi G. "Size Dependent Spectroscopy of CdSe Nanocrystallites". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.fb1.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Semiconductor crystallites which are 10's of Angstroms show a striking evolution of electronic properties with size.1 These particles (quantum dots) are large enough to exhibit a crystalline core, but small enough that solid state electronic and vibrational band structure is not yet developed. We use a recently developed synthetic method for the synthesis of high quality nanometer size (1-10 nm) II-VI semiconductor crystallites with narrow size distributions (σ <5%), emphasizing CdSe.2 Optical characterization of their electronic structure using pump-probe techniques, luminescence, and DC Stark techniques reveals both molecular and bulk-like characteristics as well as properties which are unique to nanometer size crystallites. We observe a number of discrete electronic transitions, assign them as coming from the creation of delocalized "particle-in-a-sphere" states using the theory of Ref. 3, and study their dependence on crystallite diameter.4 The Stark experiments are also compatible with the absorbing states as delocalized symmetric states. We use time resolved fluoresence line narrowing spectroscopy to study the dynamics of electron-hole recombination. We observe significant changes in electron-LO phonon coupling with time, temperature, and crystallite size and suggest that the electron-hole pair dynamics following photoexcitation are dominated by surface effects which are especially important in the smaller crystallites where a large fraction of the atoms are "surface" atoms.5
6

Small, G. J. "Applications of spectral hole-burning spectroscopies to the excited electronic states and transport dynamics of photosynthetic units". In Persistent Spectral Hole Burning: Science and Applications. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/pshb.1991.sb1.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Hole-burning methodologies suitable for the study of excited electronic state structure, energy and electron transfer dynamics, electron-phonon coupling, and heterogeneity of photosynthetic units are discussed.
7

Small, G. J., N. R. S. Reddy e R. Jankowiak. "High Pressure Hole-Burning Studies of Transport Dynamics in Photosynthetic Protein Complex". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.thd2.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Hole burning spectroscopies have proven to be powerful tools for the elucidation of the excited state (Qy) electronic structure and transport (energy, charge) dynamics of photosynthetic protein-chlorophyll complexes.1-3 Furthermore, hole burning has proven that such complexes are glass-like on a microscopic scale, which results in inhomogeneous broadenings of ~50-150 cm-1 (ΓI) for the Qy←S0 Chi absorption transitions. Importantly, it has also been shown that the zero-phonon line (ZPL) frequency distribution functions for different Qy-states of the same complex are uncorrelated, meaning that the widths of the distribution functions for energy gaps relevant to energy and electron transfer are ~21/2 ΓI. This raises the possibility that the kinetics for transport could be dispersive.4 Whether or not they are turns out to be dependent on the .strength of the electron-phonon coupling associated with the transport process. Fortunately, hole burning has proven to be capable of characterizing the nature and strength of this coupling. Required was the development of an accurate theory for entire hole profile (zero-phonon hole [ZPH] plus phonon sideband holes) applicable for arbitrarily strong electron-phonon coupling in the low temperature limit. More recently, this theory5 has been extended to arbitrary temperature.6 A key point is that the ZPH is only one small part of the entire profile. It is the entire hole profile that is important to the problem of transport dynamics in the photosynthetic unit. Thus it is that single molecule (complex) detection would be of little consequence to the problem of energy and electron transfer.
8

Highstrete, Lt Clark, e John Wessel. "Intermolecular Interactions in the Fluorene Dimer". In High Resolution Spectroscopy. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/hrs.1993.pd9.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Excited state interactions in molecular dimers and higher clusters are of increasing spectroscopic interest because the interactions reveal the nature of the intermolecular potential and provide geometrical information about clusters. Cold clusters were prepared in a supersonic beam and studied by fluorescence excitation and photoionization and spectroscopies. Past studies revealed that benzene dimers are characterized by weak intermolecular interactions in the first excited state, whereas naphthalene dimers undergo strong excimer formation that results in broad electronic spectra. Prior reports2 indicated that fluorene dimers fluoresce efficiently from a lower energy excimer state.
9

Vacha, Martin, Shinjiro Machida e Kazuyuki Horie. "Photochemical Hole Burning in the Soret Absorption Band of Zinc-tetrabenzoporphin Derivative by Two-photon Excitation". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.thf2.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
Abstract (sommario):
Line-narrowing spectroscopic techniques, such as site-selection spectroscopy (fluorescence line narrowing) and spectral hole burning, have, to our knowledge, so far failed to eliminate the effect of inhomogeneous broadening of optical transitions to the second and/or higher excited singlet electronic states (Soret absorption band) of porphin-type dyes in low temperature matrices, mainly due to: (1) Perturbations between different electronic states and resulting broadening of the homogeneous spectral bands [1], and (2) Increasing density of vibronic states with increasing transition energy and lack of correlation between individual states of different molecules. However, in a class of porphin derivatives - free-base and metallotetrabenzoporhines (TBP) - the former effects are substantially reduced. As a result, quasiline structure of S0-S2 transitions of ZnTBP in an Ar matrix [2], and later of ZnTBP in supersonic expansions [3] were observed. Further, fluorescence from S2 state of ZnTBP [2,4] and recently also of Zn-tetratolyl-TBP [5] and Zn-TPP [6] were reported.
10

Naito, Hiroyoshi. "Modulation Spectroscopies for the Characterization of Electronic Properties in Organic Semiconductor Devices". In 2021 28th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD). IEEE, 2021. http://dx.doi.org/10.23919/am-fpd52126.2021.9499130.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri

Rapporti di organizzazioni sul tema "Electronic spectroscopies":

1

Ogilvie, Jennifer P. Two-Dimensional Electronic Spectroscopies for Probing Electronic Structure and Charge Transfer: Applications to Photosystem II. Office of Scientific and Technical Information (OSTI), novembre 2016. http://dx.doi.org/10.2172/1333164.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
2

Cooke, Stephen, A. Experimentally characterizing the electronic structures of f-electron systems using advanced high resolution Fourier transform microwave spectroscopies. Office of Scientific and Technical Information (OSTI), febbraio 2013. http://dx.doi.org/10.2172/1061478.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
3

Walters, G. K., e F. B. Dunning. Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Office of Scientific and Technical Information (OSTI), giugno 1992. http://dx.doi.org/10.2172/7113541.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
4

Walters, G. K., e F. B. Dunning. Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Office of Scientific and Technical Information (OSTI), aprile 1993. http://dx.doi.org/10.2172/6520905.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
5

Morgan, M. A. Mapping of upper electronic reaction surfaces by tuned laser photolysis and by absorption and emission spectroscopies. Office of Scientific and Technical Information (OSTI), luglio 1989. http://dx.doi.org/10.2172/5655529.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
6

Walters, G. K., e F. B. Dunning. Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Progress report, 1 November 1993--31 October 1994. Office of Scientific and Technical Information (OSTI), maggio 1994. http://dx.doi.org/10.2172/10156526.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
7

Walters, G. K., e F. B. Dunning. Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Progress report, 1 November 1992--31 October 1993. Office of Scientific and Technical Information (OSTI), aprile 1993. http://dx.doi.org/10.2172/10156589.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
8

Walters, G. K., e F. B. Dunning. Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Progress report, 1 November 1991--31 October 1992. Office of Scientific and Technical Information (OSTI), giugno 1992. http://dx.doi.org/10.2172/10166548.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
9

Gallagher, A. Spectroscopic diagnostics of electron-atom collisions. Office of Scientific and Technical Information (OSTI), gennaio 1991. http://dx.doi.org/10.2172/5957609.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri
10

Beechem, Iii, Thomas Edwin, Justin Raymond Serrano e Patrick E. Hopkins. Simultaneous electronic and lattice characterization using coupled femtosecond spectroscopic techniques. Office of Scientific and Technical Information (OSTI), settembre 2009. http://dx.doi.org/10.2172/1097197.

Testo completo
Gli stili APA, Harvard, Vancouver, ISO e altri

Vai alla bibliografia