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Absorption (electromagnetic radiation)
About: Absorption (electromagnetic radiation) is a research topic. Over the lifetime, 76674 publications have been published within this topic receiving 1381221 citations.
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TL;DR: In this paper, photogenerated electrons trapped in shallow mid-gap states were proposed to originate the transient absorption and the decay kinetics of the trapped electrons were fitted to a multi-exponential formula with six lifetimes ranging from 1×10−7 to 3× 10−1 s.
191 citations
TL;DR: PAH transport was studied using isolated, perfused rabbit proximal renal tubules and it was concluded that PAH is actively transported into the tubule cell at the peritubular membrane and subsequently diffuses into the luminal fluid.
Abstract: TUNE,BRUCE M., MAURICE B. BURG,AND CLIFFORD SPATLAK. Charac~eri.ctics uf p-aminohippurata transport in proximal renal tubules. Am. J. Physiol. 217(4): 1057-1063. I969,-PAH transport was studied using isolated, perfused rabbit proximal renal tubules. ,4ctive PAH secretion was found in both the convoluted and the straight portion of the proximal tubule, but the rate of secretion was approximately 3 times as great in the straight portion. During perfusion, PAH concentration was greater in tubule cells than in luminal fluid or surrounding bath. When tubules were incubated without perfusion, PAH concentration in tubule cells was higher than during perfusion and was greater in the straight than in the convoluted portion. It is concluded that PAH is actively transported into the tubule cell at the peritubular membrane and subsequently diffuses into the luminal fluid. On the basis of this model, the permeabilities of the luminal and peritubular cell membranes to PAH were calculated. Passive PAH absorption from the tubular lumen was studied, and both the rate of efflux and tissue concentration of PAH were in agreement with the predictions made from the model. Changes in perfusion rate from 3 to 10 nl min --I had no measurable effect on the PAH secretion rate.
191 citations
TL;DR: In this article, the optical properties of pure polyvinyl alcohol (PVA) and PVA-based nanocomposite films have been investigated and the experimental results show that the absorption and absorption coefficient parameters are greatly affected by variation of copper oxide (CuO) nanoparticles concentration.
Abstract: Optical properties of pure polyvinyl alcohol (PVA) and PVA based nanocomposite films have been investigated. The nano-composite samples were prepared by the well known solution cast method. The experimental results shows that the absorption and absorption coefficient parameters are greatly affected by variation of copper oxide (CuO) nanoparticles concentration. The absorption versus wavelength for the doped samples is exponential while the absorbance of pure PVA is sharply varied with wavelength. An obvious surface plasmonic resonance peaks for the nano-composite samples were appeared. The absorption edge was greatly shifted to lower energy for the PVA doped samples. It was observed that optical band gap of pure PVA is significantly reduced upon the addition of CuO nanoparticles. The increase of refractive index with increasing CuO concentration is an evidence for the formation of new energy states and thus decreasing the energy band gap of PVA. The increase of optical dielectric constant was observed upon the addition of CuO nanoparticles. The optical dielectric loss peaks are shifted to higher wavelength with increasing the CuO concentration. The optical conductivity is increased upon the addition of CuO nanoparticles. The dispersion region in the refractive index spectra are well obeyed the single oscillator of the Wemple–Didomenico model for all the samples.
191 citations
TL;DR: In this article, two light waves with different directions of propagation derived from a pulsed Nd:YAG laser are superimposed in an absorbing sample and generate an interference field.
Abstract: Two light waves with different directions of propagation derived from a pulsed Nd:YAG laser are superimposed in an absorbing sample and generate an interference field. Due to absorption, a spatially periodic temperature distribution occurs, producing a spatial modulation of the refractive index which can be considered a thermal phase grating. The light of an argon laser simultaneously incident on the sample is diffracted by the thermal grating. When excitation is over, the decay time of the diffracted light is measured. From this decay time the thermal diffusivity of the sample is determined. Measurements on colored methanol and glycerin as well as on ruby compare favorably with the results of other authors. The possibility of exciting and detecting temperature waves (second sound) in solids by the method of light‐induced gratings is discussed.
191 citations
TL;DR: This study establishes that, in comparison to porphyrins and other tetrapyrrolic macrocyclic systems, porphycenes exhibit many desirable attributes for use as sensitizers in two-photon initiated photodynamic therapy.
Abstract: Porphycenes are structural isomers of porphyrins that have many unique properties and features. In the present work, the resonant two-photon absorption of 2,7,12,17-tetraphenylporphycene (TPPo) and its palladium(II) complex (PdTPPo) has been investigated. The data obtained are compared to those from the isomeric compound, meso-tetraphenylporphyrin (TPP). Detection of phosphorescence from singlet molecular oxygen, O2(a1Δg), produced upon irradiation of these compounds, was used to obtain two-photon excitation spectra and to quantify two-photon absorption cross sections, δ. In the spectral region of 750−850 nm, the two-photon absorption cross sections at the band maxima for both TPPo and PdTPPo, δ = 2280 and 1750 GM, respectively, are significantly larger than that for TPP. This difference is attributed to the phenomenon of so-called resonance enhancement; for the porphycenes, the two-photon transition is nearly resonant with a comparatively intense one-photon Q-band transition. The results of quantum mecha...
191 citations