Search results for "Excited state"
showing 10 items of 1387 documents
Resonances in chiral unitary approaches
2008
The extension of chiral theories to the description of resonances, via the incorporation of unitarity in coupled channels, has provided us with a new theoretical perspective on the nature of some of the observed excited hadrons. In this contribution some of the early achievements in the field of baryonic resonances are reviewed, the recent evidence of the two-pole nature of the Lambda(1405) is discussed and results on charmed baryon resonances are presented.
Theoretical spectroscopy of organic systems
1999
Abstract The complete active space (CAS) SCF method in conjunction with the multiconfigurational second-order perturbation theory (CASPT2) has been applied to study the electronically excited states of basic organic compounds. As shown in the lecture with a number of examples, the CASPT2 method is capable of yielding accurate results for relative energies and other properties of excited states, provided that flexible one-electron basis sets are employed. The applications comprise an ample range of systems and problems, including polyenes, conjugated and unconjugated dienes, alternant and nonalternant hydrocarbons, polyenals, etc. As a whole these studies enable both qualitative and quantita…
The electronic spectrum of pyrrole
1999
The electronic spectrum of pyrrole has been investigated by performing calculations using a hierarchy of coupled-cluster models consisting of CCS, CC2, CCSD, and CC3. Basis-set effects have been investigated by carrying out calculations using correlation-consistent basis sets augmented with functions especially designed for the description of Rydberg states. Oscillator strengths, excited state dipole moments, and second moments of the electronic charge distributions have been used to characterize the electronic transitions and final states. Structures and vibrational frequencies have been calculated for a few selected states, and the importance of distinguishing between vertical and adiabat…
A theoretical study of the electronic spectrum of biphenyl
1995
Abstract The electronic spectrum of biphenyl in the energy range up to 6.0 eV has been studied using multiconfigurational second-order perturbation theory (CASPT2) and a basis set of ANO type, including polarization functions on all carbon atoms. The calculated spectrum gives conclusive assignments to all valence excited singlet states and the low-lying triplet states. The change of the torsional angle between the two benzene rings in the different excited states is shown to be of considerable importance and explains the different excitation energies observed in the gas phase as compared to solution or crystalline biphenyl at low temperatures. The intense transition to the 1 1B1u state is m…
Polarization Modulation Instability in All-Normal Dispersion Microstructured Optical Fibers with Quasi-Continuous 1064 nm Pump
2019
Polarization modulation instability (PMI) is a form of modulation instability that can exist in weakly birefringent optical fibers [1]. Sidebands can be generated by this effect when a polarization mode of the birefringent fiber is excited with an intense optical pump. The polarization state of the sidebands is orthogonal to the polarization of the pump signal. PMI has been observed in microstructured optical fibers (MOFs). PMI was reported in a large-air-filling fraction MOF that was pumped in the normal dispersion regime with visible light [2]. The coherent degradation of femtosecond supercontinuum light generated in all-normal dispersion (ANDi) MOFs due to PMI was recently investigated […
Unveiling the role of upper excited electronic states in the photochemistry and laser performance of: anti -B18H22
2020
13 pags., 7 figs., -- This article is part of the themed collection: Journal of Materials Chemistry C HOT Papers
Effect of three-body forces on response functions in infinite neutron matter
2015
International audience; We study the impact of three-body forces on the response functions of cold neutron matter. These response functions are determined in the random phase approximation (RPA) from a residual interaction expressed in terms of Landau parameters. Special attention is paid to the non-central part, including all terms allowed by the relevant symmetries. Using Landau parameters derived from realistic nuclear two- and three-body forces grounded in chiral effective field theory, we find that the three-body term has a strong impact on the excited states of the system and in the static and long-wavelength limit of the response functions for which a new exact formula is established.
Dipole moments of 4′-aminoflavonols determined using electro-optical absorption measurements or molecular Stark-effect spectroscopy
2002
The electro-optical absorption measurements (EOAM) were used to measure the dipole moments of the normal form of 4 � -(methoxy)-3hydroxyflavone (FOM), 4 � -(dimethylamino)-3-hydroxyflavone (FME), and 4 � -N-(15-azacrown-5)-3-hydroxyflavone (FCR). For these probes the excited state intramolecular proton transfer (ESIPT) takes place. For comparison, the dipole moments of 4 � -(dimethylamino)-3methoxyflavone (FME3ME), for which ESIPT is lacking, were measured. In the case of FCR, FME, and FME3ME the equilibrated ground (µg) and excited Franck–Condon state (µ FC ) electrical dipole moments are parallel to each other and also parallel to the transition dipole moment. The electrical dipole moment…
Structural symmetry breaking in octupolar tetrastyrylpyrazines and their dipole moments in equilibrium ground and Franck-Condon excited state
2018
Abstract From electrooptical absorption measurements (EOAM) follows that the dipole moment of octupolar tetrastyrylpyrazines in the equilibrium ground state is large and that the change of dipole moments upon transition to the excited Franck–Condon state is significant. Obtained results unambiguously testify to structural symmetry breaking in the studied octupolar tetrastyrylpyrazines. Molecular mechanics and semi-empirical calculations evidence that tetrastyrylpyrazines have non-planar configurations. The non-planar geometry of the molecules causes large μg values and significant change of dipole moment Δaμ after excitation. Due to large μg and Δaμ values the maxima of the first absorption…
Dipole moments of aminophthalimides determined by modified electro-optical absorption and emission measurements
1995
Modified electro-optical absorption and emission methods were used to measure the electric dipole moments of five aminophthalimides in their ground and excited states. The equilibrated ground and excited state dipole moments measured by these methods are in reasonable agreement with those derived from other measurement techniques, confirming the general validity of these methods. A difference is observed between the properties of 3-aminophthalimide (3AP) and 4-amino-N-methylphthalimide (4ANMP) in different solvents. The equilibrated dipole moment of 3AP in its excited state is practically independent of the solvent polarity in contrast with 4ANMP. The possible mechanism of this effect is di…