Low-energy vibrational spectra of flexible diphenyl molecules: biphenyl, diphenylmethane, bibenzyl and 2-, 3- and 4-phenyltoluene

2014 ◽  
Vol 16 (40) ◽  
pp. 22062-22072 ◽  
Author(s):  
M. A. Martin-Drumel ◽  
O. Pirali ◽  
C. Falvo ◽  
P. Parneix ◽  
A. Gamboa ◽  
...  
Keyword(s):  
Gas Phase ◽  
Vibrational Spectra ◽  
Accurate Determination ◽  
Low Frequency ◽  
Low Energy ◽  
Vibrational Modes ◽  
Phase Spectra

Gas phase spectra of six bi-phenyl molecules are reported allowing an accurate determination of their active low-frequency vibrational modes.

scholarly journals Unknown Knowns: Case Studies in Uncertainties in the Computation of Thermochemical Parameters

2020 ◽  
Author(s):  
John Simmie
Keyword(s):  
Heat Capacity ◽  
Gas Phase ◽  
Basis Set ◽  
Statistical Thermodynamic ◽  
Vibrational Modes ◽  
Heavy Atoms ◽  
New Methods ◽  
Formation Enthalpies ◽  
Thermochemical Parameters

<div>Both the computation of, and the uncertainties associated, with gas-phase molar formation enthalpies are now quite well established for systems comprised of tens of ‘heavy’ atoms chosen from the commonest elements. The same cannot be said for derived thermochemical quantities such as entropy, heat capacity and an enthalpy function. Whilst the application of well known statistical thermodynamic relations is mostly understood, the determination of the uncertainty with which such values can be obtained has been little studied — apart, that is, for a general protocol devised by Goldsmith et al. [J. Phys. Chem. A, 2012, 116, 9033–9057]. Specific examples from that work are explored here and it is shown that their estimates are overly pessimistic. It is also evident that for some species the calculated thermochemical parameters show very little variation with either the level of theory, or basis set, or treatment of vibrational modes — this renders the inclusion of such species in databases designed to validate new methods of limited value.<br></div>

Study of a-Si:H / c-Si Heterojunctions for PV Applications

1996 ◽  
Vol 420 ◽  
Author(s):  
F. Zignani ◽  
R. Galloni ◽  
R. Rizzoli ◽  
M. Ruth ◽  
C. Summonte ◽  
...  
Keyword(s):  
Gas Phase ◽  
Open Circuit Voltage ◽  
Accurate Determination ◽  
Electrical Characterization ◽  
Silicon Layer ◽  
Open Circuit ◽  
Hydrogen Dilution ◽  
Intrinsic Efficiency

Abstracta-Si:H / c-Si heterojunction diodes were produced by PECVD with varying amorphous silicon layer thickness and hydrogen dilution of the gas phase. An accurate determination of the growth rate also in the initial stages of the deposition was made possible by an original chemical method based on the dissolution of the films followed by spectroscopical analysis of the obtained solution.The electrical characterization of the diodes confirms the generation - recombination - multitunneling nature of the transport. Although H2 dilution is important, however, beyond a certain level it is detrimental for the junction quality, probably due to the transition to a microcrystalline phase deposition. Solar cells were also produced, the best results being an open circuit voltage of 610 mV and an intrinsic efficiency of 14.2%.

scholarly journals Resolved Hyperfine at L-band for High-Spin CoEDTA, A Model for Co Sites in Proteins

2019 ◽  
Vol 20 (10) ◽  
pp. 2385
Author(s):  
William E. Antholine
Keyword(s):  
Accurate Determination ◽  
Cobalt Complex ◽  
Low Frequency ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Epr Parameters ◽  
L Band ◽  
Band Spectra

Low-frequency electron paramagnetic resonance (EPR) spectra were obtained for the Co complex of ethylene diamine tetraacetic acid (CoEDTA). It was found that the cobalt hyperfine at geff-mid is better resolved at a low frequency, L-band (1.37 GHz), and not resolved at X-band (9.631 GHz), which is the conventional frequency used for most spectra for metal complexes. Resolved cobalt hyperfine lines lead to additional EPR parameters like A-mid for cobalt and a more-accurate determination of g-mid. Resolved hyperfine lines in the L-band, but not the S-band, spectra were obtained at a concentration of 1 mM. Knowing these additional EPR parameters provides a means to better determine the electron density in the ground state orbital for each cobalt complex, as well as to determine differences upon a change of ligation. If zinc sites can be replaced by cobalt, the cobalt spectra for these sites will enhance the characterization of the zinc sites.

ACCURATE DETERMINATION OF TORSION AND PURE BENDING MOMENT FOR VISCOELASTIC MEASUREMENTS

2013 ◽  
Vol 24 ◽  
pp. 1360016
Author(s):  
YUN-CHE WANG ◽  
CHIH-CHIN KO ◽  
LI-MING SHIAU
Keyword(s):  
Material Properties ◽  
Complex Modulus ◽  
Accurate Determination ◽  
Low Frequency ◽  
Bending Moment ◽  
Magnetic Interactions ◽  
Torque Measurement ◽  
Pure Bending ◽  
Creep Tests

Measurements of time-dependent material properties in the context of linear viscoelasticity, at a given frequency and temperature, require accurate determination of both loading and deformation that are subjected to the testing materials. A pendulum-type viscoelastic spectroscopy is developed to experimentally measure loss tangent and the magnitude of dynamic modulus of solid materials. The mechanical system of the device is based on the behavior of the cantilever beam, and torsion and pure bending moment are generated from the interaction between a permanent magnet and the Helmholtz coils. The strength of the magnetic interactions may be determined with a material with known mechanical properties, such as aluminum 6061T4 alloy. The sensitivity of the torque measurement is on the order of one micro N-m level. With the high accurate torque measurement and deformation detection from a laser-based displacement measurement system, viscoelastic properties of materials can be experimentally measured in different frequency regimes. Sinusoidal driving signals are adopted for measuring complex modulus in the sub-resonant regime, and dc bias driving for creep tests in the low frequency limit. At structural resonant frequencies, the full-width-at-half-maximum (FWHM) method or Lorentzian curve fitting method is adopted to extract material properties. The completion of determining material properties in the wide frequency spectrum may help to identify the deformation mechanisms of the material and to create better models for simulation work.

Kinetic Evaluation of Carbon Formation in Steam/CO2-Natural Gas Reformers. Influence of the Catalyst Activity and Alkalinity

2002 ◽  
Vol 1 (1) ◽  
Author(s):  
Joost-Willem Snoeck ◽  
Gilbert Froment ◽  
Martin Fowles
Keyword(s):  
Natural Gas ◽  
Gas Phase ◽  
Catalyst Activity ◽  
Accurate Determination ◽  
Activity Level ◽  
Carbon Formation ◽  
Kinetic Evaluation ◽  
Detailed Kinetics ◽  
Kinetics Of

The production of synthesis gas with a low H2/CO ratio from natural gas requires recycling the produced CO2, but this enhances the risk of carbon formation. A simulation model for steam/CO2 reformers comprising detailed kinetics of the main reactions but also of the carbon formation and gasification was used to evaluate the potential of carbon formation in the bulk gas phase and inside the catalyst particles along the reactor tube. Simulation results are presented for a number of cases with varying amounts of CO2 in the feed. The model permits an accurate determination of the minimum amount of steam or the maximum amount of CO2 that can be tolerated in the feed. Thermodynamic and kinetic criteria are compared, and a strategy for the evaluation of the risk of carbon formation is proposed. The importance of the activity level of the catalyst and of its alkalinity is also illustrated.

Rapid determination of sulfide sulfur in anaerobic system by gas-phase molecular absorption spectrometry

2014 ◽  
Vol 6 (22) ◽  
pp. 9085-9092 ◽  
Author(s):  
Dong Chen ◽  
Shilei Li ◽  
Haibo Liu ◽  
Tianhu Chen ◽  
Chen Chen ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rapid Determination ◽  
Detection System ◽  
Accurate Determination ◽  
Absorption Spectrometry ◽  
Sulfide Sulfur ◽  
Molecular Absorption ◽  
Molecular Absorption Spectrometry ◽  
Anaerobic System

A detection system was designed for rapid and accurate determination of sulfide sulfur in an anaerobic system by gas-phase molecular absorption spectrometry (GPMAS).

Sign in / Sign up

Export Citation Format

Share Document