The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Takeshi Saito - One of the best experts on this subject based on the ideXlab platform.
-
a novel method for characterizing the diameter of single wall carbon nanotubes by optical absorption spectra
Applied Physics Express, 2009Co-Authors: Takeshi Saito, Shigekazu Ohmori, Bikau Shukla, Motoo Yumura, Sumio IijimaAbstract:The potentiality of optical absorption spectroscopy (OAS) for the estimation of mean diameter of single-wall carbon nanotubes (SWCNTs) from Electronic Transition energies has been explored. The observed dependence of Electronic Transition energies of both metallic and semiconducting SWCNTs on their mean diameters clearly showed that Transition energies scale inversely with the tube diameter. In the present study, the applicability of this estimation method has been experimentally confirmed for the diameter range of 1–2 nm and is expected to be useful for the characterization of wide range of diameters of SWNCTs.
Joel Tellinghuisen - One of the best experts on this subject based on the ideXlab platform.
-
Intensity analysis of overlapped discrete and continuous absorption by spectral simulation: The Electronic Transition moment for the B–X system in I2
The Journal of chemical physics, 2011Co-Authors: Joel TellinghuisenAbstract:The spectrum of I2 is examined anew in the wavelength region 520–640 nm, where discrete absorption in the B–X Transition is prominent. The spectrum is recorded with high quantitative precision at moderate resolution (0.1 nm) and is analyzed by least-squares spectral simulation, yielding the B–X Electronic Transition strength |μe|2 with unprecedented precision (
-
intensity analysis of overlapped discrete and continuous absorption by spectral simulation the Electronic Transition moment for the b x system in i2
Journal of Chemical Physics, 2011Co-Authors: Joel TellinghuisenAbstract:The spectrum of I2 is examined anew in the wavelength region 520–640 nm, where discrete absorption in the B–X Transition is prominent. The spectrum is recorded with high quantitative precision at moderate resolution (0.1 nm) and is analyzed by least-squares spectral simulation, yielding the B–X Electronic Transition strength |μe|2 with unprecedented precision (<2% relative standard error) over most of the studied region. The analysis also yields directly new estimates of the continuous absorption in this region, which support previous assessments of the A ← X Transition but lower the C(1Πu) ← X Transition strength by 25%. The new analysis method is applicable to any situation where the discrete spectrum can be simulated reliably.
Alexandre B. Rocha - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical investigations on valence vibronic Transitions
Brazilian Journal of Physics, 2005Co-Authors: Itamar Borges, Alexandre B. Rocha, Carlos E. BielschowskyAbstract:This article reviews previously employed methods to study several valence Electronic Transitions, optically forbidden or not, enhancing intensity through vibronic coupling. Electronic Transition dipole moments were calculated using several ab initio methods including electron correlation. In this method the square of the Electronic Transition dipole moments are directly calculated along the normal coordinates of vibration and then expanded with a polynomial function. Afterwards, analytical vibrational integration using harmonic wave functions, of the square of the Transition moments function, allows us to obtain partial (i.e. for each vibrational mode) and total optical oscillator strengths (OOS), for the vibronic Transition of interest. We illustrate the accuracy of the method through valence Transitions of benzene (C6H6), formaldehyde (H2CO), acetone (C3H6O) and formic acid (HCOOH).
-
intensity of the n π symmetry forbidden Electronic Transition in acetone by direct vibronic coupling mechanism
Chemical Physics Letters, 2001Co-Authors: Alexandre B. Rocha, C E BielschowskyAbstract:Abstract Absolute absorption intensities were calculated for the symmetry dipole forbidden n → π ∗ Transition in acetone. An analysis of the distribution per normal modes is performed and the results are compared with a recent calculation. Vibronic coupling mechanism is taken into account in a way that is different from the traditional Herzberg–Teller perturbation approach. In the present method the Electronic Transition moment is directly expanded in power series of the vibration normal coordinates. This approach was recently used for the equivalent n → π ∗ Transition in formaldehyde presenting an excellent agreement with the experimental results.
Sumio Iijima - One of the best experts on this subject based on the ideXlab platform.
-
a novel method for characterizing the diameter of single wall carbon nanotubes by optical absorption spectra
Applied Physics Express, 2009Co-Authors: Takeshi Saito, Shigekazu Ohmori, Bikau Shukla, Motoo Yumura, Sumio IijimaAbstract:The potentiality of optical absorption spectroscopy (OAS) for the estimation of mean diameter of single-wall carbon nanotubes (SWCNTs) from Electronic Transition energies has been explored. The observed dependence of Electronic Transition energies of both metallic and semiconducting SWCNTs on their mean diameters clearly showed that Transition energies scale inversely with the tube diameter. In the present study, the applicability of this estimation method has been experimentally confirmed for the diameter range of 1–2 nm and is expected to be useful for the characterization of wide range of diameters of SWNCTs.
Hiroshi Inomata - One of the best experts on this subject based on the ideXlab platform.
-
prediction of solvatochromic parameters of Electronic Transition energy for characterizing dipolarity polarizability and hydrogen bonding donor interactions in binary solvent systems of liquid nonpolar polar mixtures co2 expanded liquids and supercri
Journal of Molecular Liquids, 2020Co-Authors: Alif Duereh, Hiroshi InomataAbstract:Abstract Solvatochromic parameter of Electronic Transition energy (ET) provides information on dipolarity/polarizability and hydrogen bonding donor interactions in the solvation shell. In this work, a predictive framework is proposed for estimating ET values of phenol blue indicator in three mixed-solvent systems as (i) liquid nonpolar-polar mixtures, (ii) CO2-expanded liquid solvent and (iii) supercritical carbon dioxide (scCO2)-polar cosolvent mixtures. The equations of the ET framework for binary mixtures of nonpolar solvent with polar hydrogen bond acceptor (HBA) solvent can be directly adopted from the previous framework for Kamlet-Taft dipolarity/polarizability (KT-π*) [Ind. Eng. Chem. Res. 2020, 59, 12319–12330] because of the linearity of the homomorphism line between ET and KT-π* for pure nonpolar solvents and pure polar HBA solvents. However, due to specific hydrogen bonding interactions of the phenol blue with polar hydrogen bond donor (HBD) solvents, the ET framework for binary mixtures of nonpolar solvent with polar HBD solvent was the modification by the addition of HBD contribution factor. The HBD contribution factor can be simply estimated by a deviation of an actual ET value of pure HBD solvents from the homomorphism line. To validate the framework, the ET values of seventeen liquid nonpolar-polar mixtures, (ii) three CO2-expanded solvent mixtures and (iii) five scCO2-polar cosolvent mixtures collected from the literature were used. The framework was found to give a reliable ET value with an overall deviation of 0.26% and was also applicable to ET values of Reichardt, Nile red and HxQMBu2 indicators with an overall deviation of 1.73%, 0.36% and 0.40%, respectively. Only four properties of pure components are required for predictions as: (i) gas-phase dipole moment of polar component, (ii) CO2 density, (iii) ET and KT-π* values and (iv) homomorphism relationship between ET and KT-π* values.
-
Prediction of solvatochromic parameters of Electronic Transition energy for characterizing dipolarity/polarizability and hydrogen bonding donor interactions in binary solvent systems of liquid nonpolar-polar mixtures, CO2-expanded liquids and supercr
Journal of Molecular Liquids, 2020Co-Authors: Alif Duereh, Hiroshi InomataAbstract:Abstract Solvatochromic parameter of Electronic Transition energy (ET) provides information on dipolarity/polarizability and hydrogen bonding donor interactions in the solvation shell. In this work, a predictive framework is proposed for estimating ET values of phenol blue indicator in three mixed-solvent systems as (i) liquid nonpolar-polar mixtures, (ii) CO2-expanded liquid solvent and (iii) supercritical carbon dioxide (scCO2)-polar cosolvent mixtures. The equations of the ET framework for binary mixtures of nonpolar solvent with polar hydrogen bond acceptor (HBA) solvent can be directly adopted from the previous framework for Kamlet-Taft dipolarity/polarizability (KT-π*) [Ind. Eng. Chem. Res. 2020, 59, 12319–12330] because of the linearity of the homomorphism line between ET and KT-π* for pure nonpolar solvents and pure polar HBA solvents. However, due to specific hydrogen bonding interactions of the phenol blue with polar hydrogen bond donor (HBD) solvents, the ET framework for binary mixtures of nonpolar solvent with polar HBD solvent was the modification by the addition of HBD contribution factor. The HBD contribution factor can be simply estimated by a deviation of an actual ET value of pure HBD solvents from the homomorphism line. To validate the framework, the ET values of seventeen liquid nonpolar-polar mixtures, (ii) three CO2-expanded solvent mixtures and (iii) five scCO2-polar cosolvent mixtures collected from the literature were used. The framework was found to give a reliable ET value with an overall deviation of 0.26% and was also applicable to ET values of Reichardt, Nile red and HxQMBu2 indicators with an overall deviation of 1.73%, 0.36% and 0.40%, respectively. Only four properties of pure components are required for predictions as: (i) gas-phase dipole moment of polar component, (ii) CO2 density, (iii) ET and KT-π* values and (iv) homomorphism relationship between ET and KT-π* values.