335 research outputs found
Localized surface plasmon effects on the photophysics of perovskite thin films embedding metal nanoparticles
Herein we provide direct experimental evidence that proves that the photophysical properties of thin methylammonium lead iodide perovskite films are significantly enhanced by localized surface plasmon resonances (SPRs). Observations are well supported by rigorous calculations that prove that improved light harvesting can be unequivocally attributed to plasmonic scattering and near field reinforcement effects around silver nanoparticles embedded within the semiconductor layer. Adequate design of the localized SPR allows raising the absorptance of a 300 nm thick film at well-defined spectral regions while minimizing the parasitic absorption from the metallic inclusions. Measured enhancements can be as large as 80% at specific wavelengths and 20% when integrated over the whole range at which SPR occurs, in agreement with theoretical estimations. Simultaneously, the characteristic quenching effect that the vicinity of metals has on the photoluminescence of semiconductors is largely compensated for by the combined effect of the enhanced photoexcitation and the higher local density of photon states occurring at SPR frequencies, with a two fold increase of the perovskite photoemission efficiency being measuredThe research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness under grant MAT2017-88584-R (AEI/FEDER,UE). A. B. was supported by the U. S. Department of State through the Fulbright Program. S. C. P. is grateful for the support of the AEI under the Juan de la Cierva Incorporación programme (IJCI-2016-28549
Optical Responses of Localized and Extended Modes in a Mesoporous Layer on Plasmonic Array to Isopropanol Vapor
Mesoporous silica features open and accessible
pores that can intake substances from the outside. The
combination of mesoporous silica with plasmonic nanostructures
represents an interesting platform for an optical sensor based on
the dependence of plasmonic modes on the refractive index of the
medium in which metallic nanoparticles are embedded. However,
so far only a limited number of plasmonic nanostructures are
combined with mesoporous silica, including random dispersion of
metallic nanoparticles and
fl
at metallic thin
fi
lms. In this study, we
make a mesoporous silica layer on an aluminum nanocylinder
array. Such plasmonic arrangements support both localized surface
plasmon resonances (LSPRs) and extended modes which are the
result of the hybridization of LSPRs and photonic modes
extending into the mesoporous layer. We investigate
in situ
optical re
fl
ectance of this system under controlled pressure of
isopropanol vapor. Upon exposure, the capillary condensation in the mesopores results in a gradual spectral shift of the re
fl
ectance.
Our analysis demonstrates that such shifts depend largely on the nature of the modes; that is, the extended modes show larger shifts
compared to localized ones. Our materials represent a useful platform for the
fi
eld of environmental sensingEspaña MINECO grant MAT2017-88584-R
Heterodoxias y distorsiones en el arte en torno al Camino de Santiago
The article describes and analyzes several questions about art associated to the pilgrimage way to Santiago, specially focusing on medieval examples. Some aspects of these art works might seem surprising if considered from strictly orthodox perspectives, but can be explained related to their contemporary historical, artistic and cultural context. Cases referred are discussed in three groups: examples of iconography, reliquaries, and Spanish Islamic works of art
Environmental effects on the photophysics of organic-inorganic halide perovskites
The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.Peer Reviewe
Angular emission properties of a layer of rare-earth based nanophosphors embedded in one-dimensional photonic crystal coatings
The angular properties of light emitted from rare-earth based nanophosphors embedded in optical resonators built in one-dimensional photonic crystal coatings are herein investigated. Strong directional dependence of the photoluminescence spectra is found. Abrupt angular variations of the enhancement caused by the photonic structure and the extraction power are observed, in good agreement with calculated polar emission patterns. Our results confirm that the optical cavity favors the extraction of different wavelengths at different angles and that integration of nanophosphors within photonic crystals provides control over the directional emission properties that could be put into practice in phosphorescent displays.Ministerio de Ciencia e Innovación MAT2008- 02166, CSD2007-00007Junta de AndalucÃa FQM3579, FQM524
Smoking habit profile and health-related quality of life
Background: Few studies have investigated the relationship between smoking and health-related quality of life (HRQOL), and the results are not consistent. The aim of this study is to explore the association between smoking and HRQOL. Method: Cross-sectional study of 714 Spanish adults (44.7% never smokers and 55.3% smokers) without diagnosis of physical or mental disorder. Each participant provided information about different sociodemographic variables and data on HRQOL. Smokers also reported smoking-related information about smoking-related variables. Results: Nicotine dependence was not associated with the physical dimension of HRQOL, but in the mental component, nicotine dependent smokers showed worse HRQOL than never smokers (p = 0.004) and than non-nicotine dependent smokers (p = 0.014). There were no differences between no-nicotine dependent smokers and never smokers. Smoking status (non smokers vs. smokers), number of cigarettes smoked per day, stage of change, quit attempts in the past year or age of smoking onset were not related to HRQOL. Conclusions: In subjects without physical or mental diseases, only nicotine dependent smokers showed a significant impairment in the mental component of HRQOL. Therefore, it is important to consider nicotine dependence in the relationship between smoking and HRQOL.
Perfil de tabaquismo y calidad de vida relacionada con la salud. Antecedentes: pocos estudios han investigado la relación entre tabaquismo y calidad de vida relacionada con la salud (CVRS) y los resultados han sido discrepantes. El objetivo de este trabajo es analizar la relación entre consumo de tabaco y CVRS. Método: estudio transversal en el que participaron 714 adultos (44,7% no fumadores y 55,3% fumadores) sin diagnóstico de enfermedad fÃsica o mental. De cada participante se recogieron datos sociodemográficos y de CVRS, y de los fumadores también se recogió información sobre distintas variables relacionadas con el consumo de tabaco. Resultados: la dependencia de la nicotina no se asoció a la dimensión fÃsica de CVRS, pero en la dimensión mental los fumadores dependientes mostraron peor CVRS que los no fumadores (p= 0.004) y que los fumadores sin dependencia (p= 0.014). No se encontraron diferencias en función del número de cigarrillos fumados diariamente, el estadio de cambio, los intentos de abandono o la edad de inicio en el consumo de tabaco. Conclusiones: en personas sin diagnóstico de enfermedad fÃsica o mental solo los fumadores dependientes de la nicotina muestran deterioro en la dimensión mental de la CVRS. Es importante considerar el grado de dependencia de la nicotina en la relación entre consumo de tabaco y CVRS
Health-related quality of life among smoking relapsers
Background: Previous studies have shown that smoking is associated with health-related quality of life (HRQoL) impairment. In order to evaluate HRQoL in a sample of Spanish relapsers, a cross-sectional study was conducted. Method: The sample was made up of 775 smokers who had relapsed after a period of abstinence. HRQoL was evaluated using the Euro-Qol questionnaire (EQ-5D); through the descriptive profile, the EQ-5D index and the visual analogue scale (EQ-VAS). Results: Higher nicotine dependence was related to worse HRQL. According to the EQ-VAS, higher daily cigarette consumption and more years smoking were related to worse perceived health. In the EQ-5D those who had quit smoking in the previous year perceived worse health. Mobility and anxiety/ depression are the dimensions affected by smoking. Those who are more nicotine dependent (OR = 2.29) and have been smoking for longer (OR = 4.12) are more likely to have mobility problems; and those who are nicotine dependent (OR = 1.85) and relapsed more than a year ago (OR = 0.63), are more likely to experience anxiety/ depression. Conclusions: Nicotine dependence demonstrated a determining effect on HRQOL deterioration in smokers who have relapsed
Symmetry characterization of eigenstates in opal-based photonic crystals
The complete symmetry characterization of eigenstates in bare opal systems is
obtained by means of group theory. This symmetry assignment has allowed us to
identify several bands that cannot couple with an incident external plane wave.
Our prediction is supported by layer-KKR calculations, which are also
performed: the coupling coefficients between bulk modes and externally excited
field tend to zero when symmetry properties mismatch.Comment: 7 pages, 5 figures, submitted to Physical Review
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