Search results for "absorption."
showing 10 items of 2682 documents
Towards sensory Langmuir monolayers consisting of macrocyclic pentaaminoanthraquinone
2014
A pentaazamacrocycle incorporating an intracyclic anthraquinone fragment (PENTAQ) was synthesized with the aim of forming metal-responsive Langmuir monolayers. PENTAQ allows a good discrimination by naked eye of copper ions in methanol–water solutions (50 : 50 v/v). Spectrophotometric investigations of the protonation and Cu2+ binding properties of PENTAQ were undertaken in order to gain a deeper insight into the pH-dependent speciation as well as the color changing process. PENTAQ monolayers at air/water and air/methanol–water interfaces were prepared according to the Langmuir procedure. The structure of the monolayers can be tuned by varying the pH of the aqueous subphase, since it was fo…
On mathematical modelling of the solid-liquid mixtures transport in porous axial-symmetrical container with Henry and Langmuir sorption kinetics
2018
In this paper we study diffusion and convection filtration problem of one substance through the pores of a porous material which may absorb and immobilize some of the diffusing substances. As an example we consider round cylinder with filtration process in the axial direction. The cylinder is filled with sorbent i.e. absorbent material that passed through dirty water or liquid solutions. We can derive the system of two partial differential equations (PDEs), one expressing the rate of change of concentration of water in the pores of the sorbent and the other - the rate of change of concentration in the sorbent or kinetical equation for absorption. The approximation of corresponding initial b…
Ethane-Bridged Zinc-Porphyrin Dimers in Langmuir-Shäfer Thin Films: Structural and Spectroscopic Properties
2006
This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin dimers (1) in Langmuir-Scha¨fer (LS) thin films by combining scanning force microscopy (SFM) with film balance, UV-vis absorption, fluorescence, and nanosecond laser flash photolysis measurements. Results show that depending on the surface pressure the Langmuir films of pure 1 can be arranged in two different condensed phases, whereas SFM of the LS films shows characteristic fractal networks constituted by nanoscopic aggregates. The spectral findings agree with a picture in which 1 is apparently present in the anti conformation but aggregated in a sort of H-type structure whose optical features r…
Novel Lipophilic Lanthanide Bis-Phthalocyanines Functionalized by Pentadecylphenoxy Groups: Synthesis, Characterization and UV-Photostability
2012
Novel sandwich-type phthalocyanines containing a rare earth metal core (Pr, Nd, Eu-Lu) and macrocycles peripherally substituted by pentadecylphenoxy groups were synthesized using a cardanol-based phthalonitrile precursor and the respective lanthanide acetate. Additionally, the metal free-base analog compound was studied for comparison. The purified reaction products were all found to be thick and viscous substances at room temperature, showing liquid crystalline behavior with a distinct increase in fluidity at ca. 40 ° C. The complexes are readily soluble in chloroalkyl solvents and dissolve fairly well in DMF with some tendency to form aggregates. Besides they are strongly hydrophobic and …
Interface-Assisted Sign Inversion of Magnetoresistance in Spin Valves Based on Novel Lanthanide Quinoline Molecules
2018
Molecules are proposed to be an efficient medium to host spin-polarized carriers, due to their weak spin relaxation mechanisms. While relatively long spin lifetimes are measured in molecular devices, the most promising route toward device functionalization is to use the chemical versatility of molecules to achieve a deterministic control and manipulation of the electron spin. Here, by combining magnetotransport experiments with element-specific X-ray absorption spectroscopy, this study shows the ability of molecules to modify spin-dependent properties at the interface level via metal–molecule hybridization pathways. In particular, it is described how the formation of hybrid states determine…
Lanthanide-doped Y3Ga5O12 garnets for nanoheating and nanothermometry in the first biological window
2018
Abstract Absorption and luminescence spectra in the first biological window of Nd3+ single-doped and Er3+-Yb3+ co-doped Y3Ga5O12 nano-garnets have been studied to evaluate their potential use as simultaneous optical nanoheaters and nanothermometers in biomedicine. Nd3+-doped nano-garnets uses the 808 nm laser radiation, resonant with the largest absorption peak of the 4I9/2 → 4F5/2 transition, for both heating the nanoparticle and populating the 4F3/2 emitting level. Changes in the relative intensities of different emission peaks between Stark levels of the 4F3/2 (R1,2)→4I9/2 (Z1-5) transition can be directly related to the temperature of the nano-garnet. On the other hand, the Yb3+/Er3+com…
Influence of Ce codoping and H2 pre-loading on Er/Yb-doped fiber: Radiation response characterized by Confocal Micro-Luminescence
2011
International audience; Confocal microscopy luminescence measurements were applied to study the X-ray radiation response of Er/Yb-doped optical fibers in connection with H2 pre-loading and with the addition of another lanthanide element (Cerium) in the core composition. Laser excitations at 488 nm and 325 nm allow deriving the emission and absorption pattern of Er3+, the latter derived from the dips appearing in a wide luminescence band related to defects in silica. We found that the luminescence spectrum of the X-irradiated Er/Yb-doped core fiber evidences an increase in the emission intensity around 520 and 660 nm; in contrast, no changes are induced by radiation neither after H2 pre-load…
Adsorption of Rare Earth Elements onto DNA-Functionalized Mesoporous Carbon.
2020
The recovery and separation of rare earth elements (REEs) are of national importance owing to the specific usages, high demand, and low supply of these elements. In this research, we have investigated the adsorption of rare earth elements onto DNA-functionalized mesoporous carbons with a BET surface area of 605 m2/g and a median mesopore width of 48 A. Three types of single-stranded DNA, one with 100 base units of thymine, another with 20 units of thymine, and the third, a 2000 unit long DNA from salmon milt were grafted on the carboxylated mesoporous carbon surface. All of the DNA-functionalized mesoporous carbons demonstrated higher adsorption of REEs compared to pristine mesoporous carbo…
Full multiple scattering analysis of X-ray absorption near edge structure at the Eu L3-edge in EuO
2004
Abstract X-ray absorption near edge structure (XANES) at the Eu L 3 -edge in crystalline EuO is interpreted within full multiple scattering (FMS) formalism. Our theoretical results, based on the ab initio self-consistent (SC) potential calculations, are in good agreement with experimental data. The main features in the experimental signal are reproduced taking into account a cluster of about five coordination shells, centred at the europium atom and having EuO structure. An addition of more distant coordination shells makes features only better resolved. The relatively high intensity of the peak, located just above the Eu L 3 -edge, indicates that 5d states are well localised. Comparative a…
Fast and green: Sustainable rapid-prototyping of microfluidic chips on polylactic acid substrates
2018
This paper reports novel ways to bond bio-based polylactic acid (PLA) substrates for the production of sustainable, single-use, microfluidic components. A laser-based, fast (minutes) fabrication process for multi-layer microfluidic devices in PLA was reported recently but in that report, demonstrator devices were bonded with adhesive tape, which significantly reduced the devices transparency. In this paper, we propose two novel ways to bond PLA substrates, which alleviate the need for adhesives, and enable optimal device transparency.