Search results for " Reflection"
showing 10 items of 345 documents
Ultra-sensitive fluorescence spectroscopy of isolated surface-adsorbed molecules using an optical nanofiber.
2009
The strong radial confinement and the pronounced evanescent field of the guided light in optical nanofibers yield favorable conditions for ultra-sensitive surface spectroscopy of molecules deposited on the fiber. Using the guided mode of the nanofiber for both excitation and fluorescence collection, we present spectroscopic measurements on 3,4,9,10-perylenetetracarboxylic dianhydride molecules (PTCDA) at ambient conditions. Surface coverages as small as 1 per thousand of a compact monolayer still give rise to fluorescence spectra with a good signal to noise ratio. Moreover, we analyze and quantify the self-absorption effects due to reabsorption of the emitted fluorescence light by circumjac…
Analysis of multiple internal reflections in a parallel aligned liquid crystal on silicon SLM
2014
Multiple internal reflection effects on the optical modulation of a commercial reflective parallel-aligned liquid-crystal on silicon (PAL-LCoS) spatial light modulator (SLM) are analyzed. The display is illuminated with different wavelengths and different angles of incidence. Non-negligible Fabry-Perot (FP) effect is observed due to the sandwiched LC layer structure. A simplified physical model that quantitatively accounts for the observed phenomena is proposed. It is shown how the expected pure phase modulation response is substantially modified in the following aspects: 1) a coupled amplitude modulation, 2) a non-linear behavior of the phase modulation, 3) some amount of unmodulated light…
Multicommutation ATR-FTIR: determination of sodium alpha-olefin sulfonate in detergent formulations
2004
Abstract The mechanization of attenuated total reflectance measurements (ATR) in Fourier Transform Infrared spectrometry (FTIR) through the use of multicommutation has been evaluated in order to reduce the sample consumption and waste generation also avoiding risks of cells breaking. A new multicommutation ATR-FTIR procedure has been proposed for the determination of sodium alpha-olefin sulfonate (AOS) in liquid detergent formulations. The main advantages of this method are the low consumption of sample (96 ml per 100 determinations) and the analytical throughput (23 h −1 versus 15 h −1 for the manual mode). Results obtained for reference samples containing 7.52% to 9.52% (w/w) of AOS are i…
Musical video clips on YouTube as a learning tool. Practical example in university teaching
2019
Se presenta una actividad docente en un entorno universitario mediante el análisis de conceptos de la Geografía Económica a través del visionado de videoclips musicales integrados en la plataforma YouTube. El alumnado (N=33) trabaja de manera grupal y colaborativamente, en sesiones presenciales y sesiones tutorizadas, seleccionando un grupo musical y una canción y analizando en profundidad la letra y las imágenes presentes en el vídeo, con el objeto de observar e intentar resolver problemáticas cotidianas. Son los propios estudiantes quienes califican la práctica. A través de un breve cuestionario los alumnos destacan la realización de un trabajo participativo, ameno, divertido y novedoso. …
Benign — A typical nevi discrimination using diffuse reflectance and fluorescence multispectral imaging system
2015
Early diagnostics of skin cancer is of interest for dermatologists. Atypical nevi are not considered to be malignant, but are suspects that should be detected and monitored over time. The multispectral imaging system Nuance operating in spectral range 450–950 nm was adapted for clinical in vivo measurements in diffuse reflectance and fluorescence mode. Mean and standard deviation values of optical density and fluorescence intensity were extracted from segmented pigmented lesions (21 benign and 26 atypical nevi) and used for further analysis. It was possible to achieve 62% sensitivity and 67% specificity for discrimination between atypical and benign lesions using averaged fluorescence mean …
Studentu rakstiskās refleksijas pašizglītošanas veicināšanai angļu valodas stundās 11. klasē
2017
Studentu pašvirzība tiek noteikta pēc tādiem faktiem, kā studentu spēja domāt kritiski, vēlme mācīties patstāvīgi un viņiem piemīt ieradums un tieksme uz pašrefleksiju. Ar pašmācībām tiek pieņemts, ka audzēkņi ir motivēti mācīties un iekarot jaunās virsotnes kāres, izaugsmes nepieciešamības, personīgā gandarījuma no sasniegta un ziņkāres dēļ. Kad skolnieki sāk uzdot jautājumus par viņu mācību procesu, par ieradumiem un mērķiem tajā, viņi kļūst vairāk orientēti uz mērķu sasniegšanu un tādējādi vairāk iesaistīti refleksijas procesā. Refleksijas mērķis ir nodrošināt vairāk atbalsta studentiem, lai tie labāk zinātu viņu stiprās un vājās puses mācībās un tādējādi būtu vairāk pašvirzīti uz sevi m…
Integrated experimental and theoretical study on the phase transition and photoluminescent properties of ZrO2:xTb3+ (x=1, 2, 4 and 8 mol %)
2021
Abstract Zirconia (ZrO2) has been intensively studied as an important ceramic material, and numerous technological applications have been found. The present work deals with synthesizing and characterizing the phase transition (cubic vs tetragonal) and photoluminescence emissions of ZrO2:xTb3+ (x = 1,2,4 and 8 mol%). The samples formed by the complex polymerization were thoroughly characterized for physicochemical properties such powder by X-ray diffraction (XRD), and Raman and diffuse reflectance spectroscopies. First-principle calculations at the density functional theory level were performed to complement and rationalize the experimental results. An energy transfer mechanism which promote…
Skin-remitted photon path lengths: experimental study
2020
Skin-remitted picosecond laser pulses were detected at four input-output fiber distances in the spectral range 560-800 nm. After deconvolution procedures, distributions and mean values of the remitted photon path lengths in forearm skin were analyzed.
The experimental setup of the Interaction in Crystals for Emission of RADiation collaboration at Mainzer Mikrotron: Design, commissioning, and tests
2015
Silicon/germanium flat/bent crystals are thin devices able to efficiently deflect charged particle GeV-energy beams up to a few hundreds of μrad; moreover, high intensity photons can be efficiently produced in the so-called Multi-Volume Reflection (MVR) and Multiple Volume Reflections in One Crystal (MVROC) conditions. In the last years, the research interest in this field has moved to the dynamic studies of light negative leptons in the low energy range: the possibility to deflect negative particles and to produce high intensity γ sources via the coherent interactions with crystals in the sub-GeV energy range has been proved by the ICE-RAD (Interaction in Crystals for Emission of RADiation…
The Monte Carlo simulation of the Borexino detector
2017
We describe the Monte Carlo (MC) simulation package of the Borexino detector and discuss the agreement of its output with data. The Borexino MC 'ab initio' simulates the energy loss of particles in all detector components and generates the resulting scintillation photons and their propagation within the liquid scintillator volume. The simulation accounts for absorption, reemission, and scattering of the optical photons and tracks them until they either are absorbed or reach the photocathode of one of the photomultiplier tubes. Photon detection is followed by a comprehensive simulation of the readout electronics response. The algorithm proceeds with a detailed simulation of the electronics c…