Search results for "Nanocell"
showing 10 items of 31 documents
Wearable Amplifier-Photodetector System Based on PMMA/Perovskite Waveguides Integrated on a Wearable Nanocellulose Substrate
2018
From Wood and Hemp Biomass Wastes to Sustainable Nanocellulose Foams
2021
Abstract Transition to the circular economy requires the implementation of recycling and reuse routes for waste products. This research addresses one of the leading emerging areas, i.e., the development of sustainable materials and natural waste processing, namely wood and hemp byproducts. The cellulosic nanomaterials derived from these under-utilized waste residues and byproducts also serve as promising natural precursors for advanced applications, e.g., biomedical, pollution filtering, and thermal insulation. The wood and hemp fibrils were prepared by microfluidic processing of 0.2 – 1.0 wt% cellulose water suspensions. After freeze-drying, the resulting foam materials were characterized …
Integrated Optical Amplifier-Photodetector on a Wearable Nanocellulose Substrate
2018
Flexible optoelectronics has emerged as an outstanding platform to pave the road toward vanguard technology advancements. As compared to conventional rigid substrates, a flexible technology enables mechanical deformation while maintaining stable performance. The advantages include not only the development to novel applications, but also the implementation of a wearable technology directly in contact with a curved surface. Here the monolithic integration of a perovskite‐based optical waveguide amplifier together with a photodetector on a nanocellulose substrate is shown to demonstrate the feasibility of a stretchable signal manipulation and receptor system fabricated on a biodegradable mater…
Nanoporous kaolin
2017
Cellulose nano- and microfibrils (CNF/CMF) grades vary significantly based on the raw materials and process treatments used. In this study four different CNF/CMF grades were combined with kaolin clay pigment particles to form nanoporous composites. The attained composite properties like porosity, surface smoothness, mechanical properties and density properties depended strongly on the raw materials used. In general, higher kaolin content (~80 wt%) led to controllable shrinkage during drying, which resulted in improved dimensional stability of composites, compared to a lower kaolin content (~50 wt%). On the other hand, the use of a plasticizer and a high amount of CNF/CMF was essential to pr…
Circular dichroism in atomic vapors: magnetically induced transitions responsible for two distinct behaviors
2021
Atomic transitions of alkali metals for which the condition $F_e-F_g = \pm2$ is satisfied have null probability in a zero magnetic field, while a giant increase can occur when an external field is applied. Such transitions, often referred to as magnetically-induced (MI) transitions, have received interest because their high probabilities in wide ranges of external magnetic fields which, in some cases, are even higher than that of usual atomic transitions. Previously, the following rule was established: the intensities of MI transitions with $\Delta F=\pm2$ are maximum when using respectively $\sigma^\pm$ radiation. Within the same ground state, the difference in intensity for $\sigma^+$ and…
Comparison of adsorption equilibrium models and error functions for the study of sulfate removal by calcium hydroxyapatite microfibrillated cellulose…
2017
In the present study, the adsorption of sulfates of sodium sulfate (Na2SO4) and sodium lauryl sulfate (SLS) by calcium hydroxyapatite-modified microfibrillated cellulose was studied in the aqueous solution. The adsorbent was characterized using elemental analysis, Fourier transform infrared, scanning electron microscope and elemental analysis in order to gain the information on its structure and physico-chemical properties. The adsorption studies were conducted in batch mode. The effects of solution pH, contact time, the initial concentration of sulfate and the effect of competing anions were studied on the performance of synthesized adsorbent for sulfate removal. Adsorption kinetics indica…
Saturated absorption spectroscopy: elimination of crossover resonances by use of a nanocell
2007
It is demonstrated that velocity selective optical pumping/saturation resonances of reduced absorption in a Rb vapor nanocell with thickness \textit{L=} $\lambda $, 2$\lambda $, and 3$\lambda $ (resonant wavelength $\lambda $ = 780 nm) allow the complete elimination of crossover (CO) resonances. We observe well pronounced resonances corresponding to the F$_{g}=3$ $\to $ F$_{e}=2,3,4$ hyperfine transitions of the $^{85}$Rb D$_{2}$ line with linewidths close to the natural width. A small CO resonance located midway between F$_{g}=3$ $\to $ F$_{e}=3$ and F$_{g}=3$ $\to$ F$_{e}=4$ transitions appears only for \textit{L} = 4$\lambda $. The D$_{2}$ line ($\lambda $ = 852 nm) in a Cs nanocell exhi…
Calculation of modification of alkali metal atomic transition probability in strong external magnetic field and its application
2010
International audience; Interaction of alkali atoms with external magnetic field induced a splitting and a shift of their energy levels. We have study this interaction for external field from 0 to 5000 Gauss when the alkali vapor is confined in submicron thin vapor cell with thickness L = λ/2. Rubidium and Sodium vapors have been studied. The Hamiltonian can be expressed as the sum of the unperturbated atomic Hamiltonian and the so-called Zeeman Hamiltonian. The probability of a transition, induced by the laser electric field is proportional to the square of the transfer coefficients modified by the presence of the magnetic field. We will show that the strong nonlinearity of the transition …
PECULIARITIES OF RESONANT ABSORPTION AND FLUORESCENCE IN EXTREMELY THIN CELL FILLED WITH Rb AND BUFFER GAS.
2010
Recently unique extremely thin cells (ETC) containing atomic vapour of alkali metals with the column thickness L of an order and much less than optical light wavelength λ have been developed. It has been demonstrated that these ETC are a very promising tool for a fundamental study of atom-light, atom-atom, atom-surface and atom-external magnetic field interactions. Particularly, a dramatically different behaviour of resonant absorption, fluorescence and resonant magneto-optical processes compared to that obtained with the help of cm-long ordinary cells has been demonstrated. Possible applications based on ETC are described, such as magnetometers with nanometric spatial resolution and tunabl…
QUANTITATIVE SPECTROSCOPY OF Rb ATOMS IN STRONG MAGNETIC FIELD BASED ON SUBMICRON THIN VAPOUR.
2010
The energy levels of atoms placed in an external magnetic field undergo frequency shifts and changes in their transition probabilities. It is demonstrated that using fluorescence spectra from a submicron thin vapour cell (STC) with the thickness L = λ/2, it is possible to efficiently study the above mentioned changes (“half-λ Zeeman technique” (HLZT)). The circularly polarized beam of extended-cavity diode laser (λ = 794 nm, laser bandwidth γL < 1 MHz) resonant with 87Rb D1 transition, after passing through Faraday isolator is directed onto the Rb STC with the thickness L = λ/2. The temperature of the STC is 120 °C, corresponding to N ~ 1013 atom/cm3. STC was provided by a special oven with…