Search results for "state"

Protonation of the Biliverdin IXα Chromophore in the Red and Far-Red Photoactive States of a Bacteriophytochrome

2019

The tetrapyrrole chromophore biliverdin IXα (BV) in the bacteriophytochrome from Deinococcus radiodurans (DrBphP) is usually assumed to be fully protonated, but this assumption has not been systematically validated by experiments or extensive computations. Here, we use force field molecular dynamics simulations and quantum mechanics/molecular mechanics calculations with density functional theory and XMCQDPT2 methods to investigate the effect of the five most probable protonation forms of BV on structural stability, binding pocket interactions, and absorption spectra in the two photochromic states of DrBphP. While agreement with X-ray structural data and measured UV/vis spectra suggest that …

On the Low-Lying Excited States ofsym-Triazine-Based Herbicides

2005

We report a joint computational and luminescence study on the low-lying excited states of sym-triazines, namely, 1,3,5-triazine (1) and the ubiquitous herbicides atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I and 2 were computed at the TD-DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates…

First glimpse of the soft x-ray induced excited spin-state trapping effect dynamics on spin cross-over molecules.

2013

The dynamics of the soft x-ray induced excited spin state trapping (SOXIESST) effect of Fe(phen)(2)(NCS)(2) (Fe-phen) powder have been investigated by x-ray absorption spectroscopy (XAS) using the total electron yield method, in a wide temperature range. The low-spin (LS) state is excited into the metastable high-spin (HS) state at a rate that depends on the intensity of the x-ray illumination it receives, and both the temperature and the intensity of the x-ray illumination will affect the maximum HS proportion that is reached. We find that the SOXIESST HS spin state transforms back to the LS state at a rate that is similar to that found for the light induced excited spin state trapping (LI…

Some aspects of the solid state physics of yellow arsenic

1996

Long-Lived Electronic Coherence of Iodine in the Condensed Phase: Sharp Zero-Phonon Lines in the B↔X Absorption and Emission of I2 in Solid Xe

2015

Our study of B←X absorption of molecular iodine (I2) isolated in a low-temperature crystalline xenon has revealed an exceptionally long-lived electronic coherence in condensed phase conditions. The visible absorption spectrum shows prominent vibronic structure in the form of zero-phonon lines (ZPLs) and phonon side bands (PSBs). The resolved spectrum implies weak interaction of the chromophore to the lattice degrees of freedom. The coherence extends past the vibrational period of the excited state molecule, unlike that observed in any condensed phase environment for I2 so far. The ZP transitions from the relaxing B-state populations were resolved in the hot luminescence when the 532 nm lase…

Fabrication and characterization of vacuum deposited fluorescein thin films

2011

Simple vacuum evaporation technique for deposition of dyes on various solid surfaces has been developed. The method is compatible with conventional solvent-free nanofabrication processing enabling fabrication of nanoscale optoelectronic devices. Thin films of fluorescein were deposited on glass, fluorine-tin-oxide (FTO) coated glass with and without atomically layer deposited (ALD) nanocrystalline 20 nm thick anatase TiO2 coating. Surface topology, absorption and emission spectra of the films depends on their thickness and the material of supporting substrate. On a smooth glass surface the dye initially formes islands before merging into a uniform layer after 5 to 10 monolayers. On FTO cove…

Polarization-Dependent Disappearance of a Resonance Signal -- Indication for Optical Pumping in a Storage Ring?

2021

We report on laser spectroscopic measurements on Li$^+$ ions in the experimental storage ring ESR at the GSI Helmholtz Centre for Heavy Ion Research. Driving the $2s\,^3\!{S}_1\;(F=\frac{3}{2}) \,\leftrightarrow\,2p\,^3\!P_2\;(F=\frac{5}{2}) \leftrightarrow 2s\,^3\!{S}_1\;(F=\frac{5}{2})$ $\Lambda$-transition in $^7$Li$^+$ with two superimposed laser beams it was found that the use of circularly polarized light leads to a disappearance of the resonance structure in the fluorescence signal. This can be explained by optical pumping into a dark state of polarized ions. We present a detailed theoretical analysis of this process that supports the interpretation of optical pumping and demonstrate…

Il contratto collettivo aziendale in una prospettiva comparata. Italia, Francia, Spagna e Stati Uniti a confronto

2014

Sulla scorta del metodo comparato, la tesi analizza le recenti modifiche alla disciplina del contratto collettivo aziendale in Italia, Francia e Spagna, introdotte dalla legge e dagli accordi interconfederali; l'obiettivo è dimostrare un tendenziale avvicinamento degli stati europei analizzati al sistema nord-americano di relazioni industriali, in cui il rapporto di lavoro è regolato non tanto dalla legge o dall'accordo di categoria, ma dal contratto aziendale.Vengono inoltre analizzati i recenti accordi collettivi firmati alla Fiat ed alla Chrysler a partire dal processo di integrazione iniziato nel 2009. According to the comparative method, the thesis analyses the recent changes to the di…

Claridad y calidad de las notas explicativas en estados financieros bajo IFRS. Un estudio de brechas de Expectativas Gaps para normas contables (NIC …

2018

Este análisis situacional de la claridad y calidad de las notas explicativas en los estados financieros bajo IFRS (Obligatory Disclosure), pretende entregar claridad acerca de la calidad de la información entregada en las notas explicativas para 4 normas de Información Contable, claves en la información financiera en los países de la región, que son la NIC 2; Notas referente a Inventarios, NIC 16; Notas referente a Propiedad Planta y Equipos, NIC 37; Notas referente a Provisiones, y NIC 38; Notas referente a Activos Intangibles. Adicionalmente, este trabajo estudia la brecha de expectativas (Expectation Gaps) que existe en la información entregada en las notas de los estados financieros par…

INTEGRAL observations of the peculiar BeX System SAX J2103.5+4545

2004

We present an INTEGRAL data analysis of the X-ray transient \object{SAX J2103.5+4545} during two outbursts detected in December 2002. The INTEGRAL coordinates and error circle agree with the position of the recently proposed optical counterpart. A power-law plus cut-off model provided a good fit to the 4-150 keV spectrum yielding a photon index of 1.0+-0.1, a cut-off energy E_cut=7.6+-2.0 keV and a folding energy E_fold=30.9+-2.5 keV. The X-ray luminosity in the 4-150 keV energy range was found to be 6.0x10^36 erg/s, assuming a distance of 6.5 kpc. This luminosity, together with the derived photon index, indicate that the source is in a bright state. A 354.9$+-0.5 second pulse period is mea…