Search results for "Rafa"

Time‐resolved absorption and luminescence following electron‐hole pair creation in ZnO

2008

We report transient absorption induced by electron-hole excitation in undoped ZnO. A laser pump/continuum probe method covers 2–300 ps, and an electron pulse with lamp transmission covers 8–300 ns. The broad absorption spectrum increases monotonically with wavelength from 900 to 1600 nm. Following a reasonable hypothesis that the free-carrier-like induced infrared absorption is proportional to the total number of free carriers, excitons, and shallow-trapped carriers in the sample, these data allow setting an upper limit on the quantum efficiency of a specified lifetime component of luminescence. For the undoped commercial ZnO studied in this report, the quantum efficiency of room temperatur…

Intramolecular charge transfer and dual fluorescence of 4-(dimethylamino)benzonitrile: ultrafast branching followed by a two-fold decay mechanism.

2011

International audience; In this contribution we present new experimental and theoretical results for the intramolecular charge transfer (ICT) reaction underlying the dual fluorescence of 4-(dimethylamino) benzonitrile ( DMABN), which indicate that the fully twisted ICT (TICT) state is responsible for the time-resolved transient absorption spectrum while a distinct partially twisted ICT (pTICT) structure is suggested for the fluorescent ICT state.

Unraveling long-term changes in lake color based on optical properties of lake sediment

2020

A number of boreal surface waters have become browner over the last two decades. Recovery from acid rain is regarded as an important driver for this lake color increase, indicating a general browner lake color in preindustrial times. However, the lack of long-term monitoring data makes it challenging to unravel historical changes in lake color. In this study, we estimated long-term development in lake color (1800 to 2015) based on the optical properties of alkaline extractable dissolved organic matter (DOM) from sediment using UV–Vis and fluorescence spectroscopy. We found that the present lake color (2015) was significantly browner (four times higher in absorption coefficient) than for the…

Transient absorption studies of the Ru(dcbpy)2(NCS)2 excited state and the dye cation on nanocrystalline TiO2 film

2001

We have measured dynamics of the Ru(dcbpy)2(NCS)2 [dcbpy = 4,4′-dicarboxy-2,2′-bipyridine] excited state and the dye cation on nanocrystalline TiO2 film in the wavelength region 700–900 nm. The dye in ethanol solution and Ru(dcbpy)2(NCS)2 sensitized nanocrystalline Al2O3 films were used as non-injecting reference samples for excited state identification. For TiO2/Ru(dcbpy)2(NCS)2 film the `reactant' decay and `product' formation kinetics observed at different probe wavelengths showed that the resolved transient absorption picosecond components (1.1±0.2), (12±2) and (100±5) ps are related to electron injection from the excited states of the dye to the semiconductor TiO2.

Photoinduced interfacial electron injection in RuN3–TiO2 thin films: Resolving picosecond timescale injection from the triplet state of the protonate…

2008

Using femtosecond transient absorption spectroscopy we have studied light-induced electron injection from the sensitizer RuN3 and its partly deprotonated tetrabutylamonium salt to nano-structured TiO2 film. Previous studies have suggested significant differences in electron injection dynamics for these dyes and some results have indicated that aggregation of the sensitizer may lead to slow injection. By measuring transient absorption spectra and kinetics of RuN3 and RuN3-TBA in solution and attached to TiO2 film we show that the electron injection dynamics are very similar for the two forms of the dye and that aggregation has only moderate effects on the electron transfer dynamics. (c) 2008…

Asymmetries in the momentum distributions of electrons stripped by a XUV chirped pulse in the presence of a laser field

2012

The ionization of hydrogen by a chirped XUV pulse in the presence of a few cycle infrared laser pulse has been investigated. The electron momentum distribution has been obtained by treating the interaction of the atom with the XUV radiation at the first order of the time-dependent perturbation theory and describing the emitted electron through the Coulomb-Volkov wavefunction. The results of the calculations agree with the ones found by solving numerically the time-dependent Schr¨odinger equation. It has been found that depending on the delay between the pulses the combined effect of the XUV chirp and of the steering action on the infrared field brings about asymmetries in the electron momen…

Journeys from quantum optics to quantum technology

2017

Sir Peter Knight is a pioneer in quantum optics which has now grown to an important branch of modern physics to study the foundations and applications of quantum physics. He is leading an effort to develop new technologies from quantum mechanics. In this collection of essays, we recall the time we were working with him as a postdoc or a PhD student and look at how the time with him has influenced our research.

Sesión apologética dedicada á D. Rafael Cisternas y Fontseré : discurso leído en la apertura de curso de 1894 del Instituto Médico Valenciano

1894

Villancico y poesias para la solemne profesion que hace en el Real Convento de la Puridad de esta ciudad de Valencia la Sra. S. Rafaela Escoto y Rico…

Només el text, sense la música Text a 1 col Sign.: [ ]6 Esc. xil. dels Franciscans a port Esc. xil. en p. [3 Bandes

Gozos a San Rafael Arcangel, venerado en la Parroquial de San Miguel Arcangel de Valencia

1750

El full orlat Grav. xil. enmarcat de "S. Rafael Arcangel", flanquejat per gerros amb flors El text del goig a tres col., separades per filets