scholarly journals Femtosecond Transient Absorption Microspectroscopy of Benzil Confined Into a Single Bead of Porous Glass

1996 ◽  
Vol 16 (3) ◽  
pp. 197-206 ◽  
Author(s):  
Christopher F. Porter ◽  
Naoto Tamai ◽  
Hiroshi Masuhara
Keyword(s):  
Pore Diameter ◽  
Transient Absorption ◽  
Polar Solvent ◽  
Photophysical Properties ◽  
Free Solution ◽  
Average Pore ◽  
Porous Glasses ◽  
Planar Form ◽  
Femtosecond Transient Absorption ◽  
Single Bead

The photophysical properties of benzil dissolved in free solution and in solution confined into a single bead of porous glasses (size < 100 μm) were investigated by femtosecond transient absorption microspectroscopy. In nonpolar solvent, cyclohexane, the rate of conformational change from the skewed to the near trans-planar form was reduced from 2.2 × 1012s-1 in free solution to 9.1 × 1011s-1 in porous glasses with an average pore diameter of 26 nm. In polar solvent, DMF, however, there was little difference between the two systems.

Structure and Conductivity of Nanostructured Sodium Nitrite

2006 ◽  
Vol 115 ◽  
pp. 221-228 ◽  
Author(s):  
I. Golosovsky ◽  
V. Dvornikov ◽  
T. Hansen ◽  
A. Fokin ◽  
E. Koroleva ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Ionic Conductivity ◽  
Neutron Diffraction ◽  
Sodium Nitrite ◽  
Pore Diameter ◽  
Conductivity Measurements ◽  
Average Pore ◽  
Porous Glasses ◽  
Evolution Of Structure ◽  
Good Agreement

Combined neutron diffraction, dielectric and conductivity measurements of NaNO2 embedded into porous glasses with average pore diameter 7 nm are performed in the ferroelectric and paraelectric phases. The temperature interval of existence of a volume premelted state in this confined material is determined. It is shown that the observed earlier giant growth of dielectric constant above TC can be attributed with an appearance of ionic conductivity due to jumping diffusion (or hopping) of constituent ions. These data are in a good agreement with experimental results of our earlier measurements of temperature evolution of structure of this nanocomposite material.

scholarly journals Critical Point Drying: An Effective Tool for Direct Measurement of the Surface Area of Pretreated Cellulosic Biomass

2018 ◽  
Author(s):  
Kyu-Young Kang ◽  
Kyung Ran Hwang ◽  
Ji-Yeon Park ◽  
Joon-Pyo Lee ◽  
Jun-Seok Kim ◽  
...  
Keyword(s):  
Critical Point ◽  
Surface Area ◽  
Freeze Drying ◽  
Pore Diameter ◽  
Polar Solvent ◽  
Cellulosic Biomass ◽  
Average Pore ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Bet Technique

Surface area and pore size distribution of Eucalyptus samples pretreated by different methods were determined by the Brunauer-Emmett-Teller (BET) technique. Three methods were applied to prepare cellulosic biomass samples for BET measurements: air, freeze, and critical point drying (CPD). Air and freeze drying caused severe collapse of biomass pore structures, but CPD effectively preserved biomass morphology. Surface area of CPD prepared Eucalyptus samples was determined to be 58&ndash;161 m2/g, whereas air and freeze dried samples were 0.5&ndash;1.3 and 1.0&ndash;2.4 m2/g, respectively. Average pore diameter of CPD prepared Eucalyptus samples were 61&ndash;70&Aring;. CPD preserved Eucalyptus sample morphology by replacing water with a non-polar solvent, CO2 fluid, which prevented hydrogen bond reformation in the cellulose.

Probing the Structural Features and the Micro-heterogeneity of Various Deep Eutectic Solvents and their Water Dilutions by the Photophysical Behaviour of Two Fluorophores

2020 ◽  
Author(s):  
Matteo Tiecco ◽  
Irene Di Guida ◽  
Pier Luigi Gentili ◽  
Raimondo Germani ◽  
Carmela Bonaccorso ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Deep Eutectic Solvents ◽  
Structural Features ◽  
Solvation Dynamics ◽  
Structured Systems ◽  
Reduced Viscosity ◽  
Bond Network ◽  
Fluorescent Molecules

<div><div><div><p>The structural features of a series of diverse Deep Eutectic Solvents (DESs) have been investigated and characterized by means of two fluorescent probes. The spectral and photophysical properties of the latter are strictly dependent on the experienced environment, so that they can provide insights into the polarity, viscosity, hydrogen-bond network, and micro-heterogeneity of the various DESs.</p><p>In fact, the investigated DESs exhibit a variety of properties with regards to their hydrophilicity, acidity, and hydrogen-bond ability, and these details were deeply probed by the two fluorescent molecules. The effect of the addition of water, which is a key strategy for tuning the properties of these structured systems, was also tested. In particular, the excited state dynamics of the probes, measured by femtosecond-resolved transient absorption, proved instrumental in understanding the changes in the structural properties of the DESs, namely reduced viscosity and enhanced heterogeneity, as the water percentage increases. Differences between the various DESs in terms of both local microheterogeneity and bulk viscosity also emerged from the peculiar multi-exponential solvation dynamics undergone by the excited states of the probes.</p></div></div></div>

Probing the Structural Features and the Micro-heterogeneity of Various Deep Eutectic Solvents and their Water Dilutions by the Photophysical Behaviour of Two Fluorophores

2020 ◽  
Author(s):  
Matteo Tiecco ◽  
Irene Di Guida ◽  
Pier Luigi Gentili ◽  
Raimondo Germani ◽  
Carmela Bonaccorso ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Deep Eutectic Solvents ◽  
Structural Features ◽  
Solvation Dynamics ◽  
Structured Systems ◽  
Reduced Viscosity ◽  
Bond Network ◽  
Fluorescent Molecules

<div><div><div><p>The structural features of a series of diverse Deep Eutectic Solvents (DESs) have been investigated and characterized by means of two fluorescent probes. The spectral and photophysical properties of the latter are strictly dependent on the experienced environment, so that they can provide insights into the polarity, viscosity, hydrogen-bond network, and micro-heterogeneity of the various DESs.</p><p>In fact, the investigated DESs exhibit a variety of properties with regards to their hydrophilicity, acidity, and hydrogen-bond ability, and these details were deeply probed by the two fluorescent molecules. The effect of the addition of water, which is a key strategy for tuning the properties of these structured systems, was also tested. In particular, the excited state dynamics of the probes, measured by femtosecond-resolved transient absorption, proved instrumental in understanding the changes in the structural properties of the DESs, namely reduced viscosity and enhanced heterogeneity, as the water percentage increases. Differences between the various DESs in terms of both local microheterogeneity and bulk viscosity also emerged from the peculiar multi-exponential solvation dynamics undergone by the excited states of the probes.</p></div></div></div>

Fuels Desulphurisation by Adsorbtion on Fe / Bentonite

2017 ◽  
Vol 68 (3) ◽  
pp. 483-486
Author(s):  
Constantin Sorin Ion ◽  
Mihaela Bombos ◽  
Gabriel Vasilievici ◽  
Dorin Bombos
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Adsorption Process ◽  
Continuous System ◽  
Gas Oil ◽  
Average Pore ◽  
Atmospheric Distillation

Desulfurisation of atmospheric distillation gasoline and gas oil was performed by adsorption process on Fe/ bentonite. The adsorbent was characterized by determining the adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments of atmospheric distillation gasoline and gas oil were performed in continuous system at 280�320oC, 5 atm and volume hourly space velocities of 1�2 h-1. The efficiency of adsorption on Fe / bentonite was better at desulphurisation of gasoline versus gas oil.

scholarly journals Femtosecond Transient Absorption Studies of Two Novel Energetic Tetrazole Derivatives

2021 ◽  
pp. 100016
Author(s):  
Naga Krishnakanth Katturi ◽  
Chinmoy Biswas ◽  
Nagarjuna Kommu ◽  
Sai Santosh Kumar Raavi ◽  
Venugopal Rao Soma
Keyword(s):  
Transient Absorption ◽  
Femtosecond Transient Absorption ◽  
Absorption Studies ◽  
Tetrazole Derivatives

scholarly journals Photocatalytic activity of Pr-modified TiO2 for the degradation of bisphenol A

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Denise S. Cordeiro ◽  
Fernando L. Cassio ◽  
Larissa Ciccotti ◽  
Thiago L. R. Hewer ◽  
Paola Corio ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Bisphenol A ◽  
Pore Diameter ◽  
Sol Gel ◽  
Bandgap Energy ◽  
Photocatalytic Efficiency ◽  
Average Pore ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Adsorption Desorption

AbstractPraseodymium doped TiO2 nanoparticles were successfully prepared by the sol–gel method and characterized by X-ray powder diffraction, N2 adsorption–desorption isotherm, and UV–vis spectroscopy. The effects of the dopant on the crystallite size, specific surface area, average pore diameter, pore volume, and bandgap energy were investigated. The photocatalytic activity of the catalysts was evaluated by bisphenol A degradation and mineralization, which is a representative endocrine disruptor. Furthermore, under visible light irradiation the Pr-modified TiO2 photocatalysts exhibited higher photocatalytic efficiency than unmodified TiO2. When praseodymium was loaded (1.0–5.0%) onto the surface of TiO2, the rates of degradation and mineralization were increased 3–5 times.

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