Excited State Dynamics
Mostrando 13-24 de 52 artigos, teses e dissertações.
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13. "Não linearidades ópticas em azocompostos" / Optical nonlinearities in azocompounds
This work reports on the temperature dependence of linear and nonlinear properties of azocompounds solutions due to isomerization mechanisms. The dependence of pipi* transitions on the linear structure of azocompounds is already noticeble in the measurements of absorption spectra as function of the temperature for the trans isomer. Knowing the energy levels
Publicado em: 2004
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14. Dinamica de sistemas quanticos : atomos em cavidades de ions aprisionados
In this thesis we studied the dynamics of two quantum systems: atoms in a cavity and trapped ions. For atoms in a cavity ( QED ) , we studied the dynamics of field prepared in a superposition of coherent states and a statistical mixture. In this system, using a Intensity-Dependence Jaynes-Cummings model (DNJCM) we discuss some aspects of the dynamics of atom
Publicado em: 2002
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15. Nonlinear optical properties of aniline oligomers / Propriedades ópticas não-lineares de oligômeros de anilina
We report on the study of electronic optical non linearities in two aniline oligomers: dimer and the tetramer. Four tetramer concentrations were measured, pure and also 33 and 100% doped; one of dimer non doped another 100% doped. The solutions were prepared using dimethyl sulfoxide (DMSO) as solvent and the doping was performed with hydrochloric acid. The s
Publicado em: 2002
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16. Dynamic of optical nonlinearities in macromolecules and oligomers / Dinâmica de não linearidades ópticas em macromoléculas e oligômeros
This work reports the dynamic nonlinear optical properties of organic compounds, namely, ytterbium bis-phthalocyanine, furfuryl alcohol derivatives and azo-aromatic compounds. In order to carry out this investigation we developed an experimental extension to the standard Z-scan technique, named Z-scan with pulse trains. In this method, pulse trains contained
Publicado em: 2000
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17. Dinamica de femtossegundos em pontos quanticos de CdTe
We study the ultrafast phenomena in CdTc Quantum Dots in Borosilicate Glasses using short laser pulses (femtoseconds) methods. Measuring the Time Resolved Differential Transmission Spectroscopy we find infrared shifts of the bleached spectra. For the interpretation of these data we study the Electronic Structure of CdTe with 0-D Quantum Confinement. We deter
Publicado em: 1998
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18. Ultra-fast excited state dynamics in green fluorescent protein: multiple states and proton transfer.
The green fluorescent protein (GFP) of the jellyfish Aequorea Victoria has attracted widespread interest since the discovery that its chromophore is generated by the autocatalytic, posttranslational cyclization and oxidation of a hexapeptide unit. This permits fusion of the DNA sequence of GFP with that of any protein whose expression or transport can then b
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19. The relaxation dynamics of the excited electronic states of retinal in bacteriorhodopsin by two-pump-probe femtosecond studies
We present the results of two-pump and probe femtosecond experiments designed to follow the relaxation dynamics of the lowest excited state (S1) populated by different modes. In the first mode, a direct (S0 → S1) radiative excitation of the ground state is used. In the second mode, an indirect excitation is used where the S1 state is populated by the use o
The National Academy of Sciences.
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20. Photoexcited breathers in conjugated polyenes: An excited-state molecular dynamics study
π-conjugated polymers have become an important class of materials for electronic devices. Design of these devices requires understanding such processes as photochemical reactions, spatial dynamics of photoexcitations, and energy and charge transport, which in turn involve complex coupled electron-vibrational dynamics. Here we study nonlinear photoexcitation
The National Academy of Sciences.
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21. Molecular dynamics study of early picosecond events in the bacteriorhodopsin photocycle: dielectric response, vibrational cooling and the J, K intermediates.
Molecular dynamics simulations have been carried out to study the J625 and K590 intermediates of bacteriorhodopsin's (bRs) photocycle starting from a refined structure of bR568. The coupling between the electronic states of retinal and the protein matrix is characterized by the energy difference delta E(t) between the excited state and the ground state to wh
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22. Fluorescence correlation spectroscopy reveals fast optical excitation-driven intramolecular dynamics of yellow fluorescent proteins
Fast excitation-driven fluctuations in the fluorescence emission of yellow-shifted green fluorescent protein mutants T203Y and T203F, with S65G/S72A, are discovered in the 10−6–10−3-s time range, by using fluorescence correlation spectroscopy at 10−8 M. This intensity-dependent flickering is conspicuous at high pH, with rate constants independent of
The National Academy of Sciences.
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23. Redox effects on the excited-state lifetime in chlorosomes and bacteriochlorophyll c oligomers.
Oligomers of [E,E] BChl CF (8, 12-diethyl bacteriochlorophyll c esterified with farnesol (F)) and [Pr,E] BChl CF (analogously, M methyl, Pr propyl) in hexane and aqueous detergent or lipid micelles were studied by means of steady-state absorption, time-resolved fluorescence, and electron spin resonance spectroscopy. The maximum absorption wavelength, excited
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24. Ultrafast spectroscopy of the visual pigment rhodopsin.
We report on time-resolved absorption studies of the bovine visual pigment rhodopsin with subpicosecond resolution at room temperature. Our data show that bathorhodopsin, rhodopsin's early photoproduct, is photochemically formed in 3.0 +/- 0.7 ps. The data suggest that bathorhodopsin formation is kinetically preceded by two species along the rhodopsin-to-bat