Yoshinori Murakami - Academia.edu (original) (raw)
Papers by Yoshinori Murakami
Shock Waves, Sep 1, 2003
Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the r... more Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the reflected shock of cyclo-C5H6/O2/Ar and C6H5OCH3/O2/Ar mixtures. In both mixtures we could observe the formation of O atoms produced by the reaction of cyclo-C5H5+ O2 → cyclo-C5H5O + O and from the kinetic analysis of these time profiles the rate constant for this reaction was determined to be k = 8.5 × 10 14 exp(−117.0 kJ/RT) cm 3 mol −1 s −1. The possibility of CO formation by the reaction of cyclo-C5H5O → C4H5+ CO was also investigated but because of the subsequent reactions forming CO molecules no direct information for the reaction of cyclo-C5H5O → C4H5+ CO was derived.
The Journal of Physical Chemistry, 1993
Absolute concentrations of H atoms and OH radicals were measured to determine the product branchi... more Absolute concentrations of H atoms and OH radicals were measured to determine the product branching ratios for the reactions SiH 3 +O 2 →SiH 2 O+OH (1b) and SiH 3 +O 2 →SiH 2 O 2 +H (1c) by using laser-induced fluorescence (LIF) techniques. The intensity of the VUV-LIF signal of H atoms at Lyman α wavelength was calibrated against the absolute concentration determined by the simultaneous measurement of the Lyman α resonant absorption
SAE Technical Paper Series, 2013
The journal of physical chemistry. A, Jan 13, 2005
The fundamental heat transfer phenomena caused by the 1064 nm pulsed laser irradiations on the mo... more The fundamental heat transfer phenomena caused by the 1064 nm pulsed laser irradiations on the molybdenum aerosol particles were investigated by monitoring the time evolutions of the incandescence spectra using an ICCD detector with a multichannel spectrograph. The particle temperatures were evaluated from the incandescence spectra with the Planck function, and the cooling processes of the laser-heated particles were investigated. By measuring the decrease in the laser-heated particle temperatures with different surrounding media, the roles of the heat transfer processes such as vaporization, thermal radiation, and heat conduction to the surrounding media were discussed. The influences of the vaporization processes on the total heat transfer phenomena were investigated by monitoring the emissions of the constituent molybdenum atoms in the laser-induced incandescence spectra of the aerosol particles and also by investigating the relationships between the intensity of the incandescenc...
ChemInform, 2005
For Abstract see ChemInform Abstract in Full Text.
The Journal of Physical Chemistry C, 2007
Diffusion of OH radicals from UV-irradiated TiO 2 surface to the gas phase was successfully detec... more Diffusion of OH radicals from UV-irradiated TiO 2 surface to the gas phase was successfully detected using a laser-induced-fluorescence technique for various types of TiO 2 powders. The diffusion time of OH radicals was found to vary with the types of TiO 2 powders and to be affected by the heat treatments of these powders, depending on the treatment temperatures. The diffusion mechanism was discussed based on the characteristic OH-LIF intensities for individual TiO 2 powders and the observations of OD-LIF after the exposure of D 2 O vapors over the TiO 2 powders. The quantum yield of OH radicals diffused from the TiO 2 surface was estimated to be about 5 × 10-5 by comparing the OH-LIF intensities produced by the 266-nm photolysis of HNO 3.
The Journal of Physical Chemistry B, 2006
The important roles of OH radicals for remote oxidation using TiO 2 photocatalysts were evidenced... more The important roles of OH radicals for remote oxidation using TiO 2 photocatalysts were evidenced by the in situ detection of OH radicals in the gas phase using the laser-induced fluorescence (LIF) technique. The appearance of OD-LIF intensities after the exposure of D 2 O vapors over TiO 2 powders and the decrease of the time-resolved signals of OH-LIF intensities with increasing calcined temperatures of TiO 2 powders suggested that the exchangeable water at the TiO 2 surface is the origin of the diffused OH radicals.
The Journal of Physical Chemistry A, 2009
Theoretical calculations at the CBS-QB3 level of theory have been performed to investigate the po... more Theoretical calculations at the CBS-QB3 level of theory have been performed to investigate the potential energy surface for the reaction of o-, m-and p-xylyl with molecular oxygen. The differences of the relative potential energies for the products and the transition states of o-, m-and p-xylyl with molecular oxygen were found to be within 8.5 kJ/mol at the CBS-QB3 level of theory. Although the reaction of m-and p-xylyl radicals with molecular oxygen have the same reaction pathways and also the same reaction thermochemistry as that of benzyl radicals, the o-xylylperoxy radicals formed by the reaction of o-xylyl + O 2 had an additional intramolecular isomerization pathway to form the o-xylyl hydroperoxy radicals. The rate constants and the product branching ratios for the o-xylyl + O 2 and its subsequent reactions were evaluated by the RRKM and master equation analysis. Possible roles for these reaction pathways on the combustion of o-xylenes are discussed.
The Journal of Physical Chemistry A, 2007
Ab initio calculations at the level of CBS-QB3 theory have been performed to investigate the pote... more Ab initio calculations at the level of CBS-QB3 theory have been performed to investigate the potential energy surface for the reaction of benzyl radical with molecular oxygen. The reaction is shown to proceed with an exothermic barrierless addition of O 2 to the benzyl radical to form benzylperoxy radical (2). The benzylperoxy radical was found to have three dissociation channels, giving benzaldehyde (4) and OH radical through the four-centered transition states (channel B), giving benzyl hydroperoxide (5) through the six-centered transition states (channel C), and giving O 2-adduct (8) through the four-centered transition states (channel D), in addition to the backward reaction forming benzyl radical and O 2 (channel E). The master equation analysis suggested that the rate constant for the backward reaction (E) of C 6 H 5 CH 2 OO f C 6 H 5 CH 2 + O 2 was several orders of magnitude higher that those for the product dissociation channels (B-D) for temperatures 300-1500 K and pressures 0.1-10 atm; therefore, it was also suggested that the dissociation of benzylperoxy radicals proceeded with the partial equilibrium between the benzyl + O 2 and benzylperoxy radicals. The rate constants for product channels B-D were also calculated, and it was found that the rate constant for each dissociation reaction pathway was higher in the order of channel D > channel C > channel B for all temperature and pressure ranges. The rate constants for the reaction of benzyl + O 2 were computed from the equilibrium constant and from the predicted rate constant for the backward reaction (E). Finally, the product branching ratios forming CH 2 O molecules and OH radicals formed by the reaction of benzyl + O 2 were also calculated using the stationary state approximation for each reaction intermediate.
The Journal of Physical Chemistry A, 2003
The main concern of this study is to investigate the reaction mechanism of O + COS f products (1)... more The main concern of this study is to investigate the reaction mechanism of O + COS f products (1). Experiments are conducted by use of an excimer laser photolysis shock tube technique, where mixtures of COS and SO 2 diluted in Ar are photolyzed behind reflected shock waves. Time-resolved measurements of O and S atoms are conducted by use of atomic resonance absorption spectroscopy, and the overall rate constant of (1) is determined by the O atom decay at temperatures 1250-1600 K, i.e., k 1) 10-10.18(0.26 exp[-(22.5 (7.1) kJ‚mol-1 /RT] cm 3 molecule-1 s-1 , which is in good agreement with the former recommendation. It is confirmed in this experiment that the S atom is a direct product of reaction 1. By analysis of time profiles of the S atom, the branching fraction of the S production channel O + COS f S + CO 2 (1b), R, is determined against the main channel O + COS f CO + SO (1a), where the S atom consumption reactions, S + SO 2 f 2SO (2) and S + COS f S 2 + CO (3), are inevitably taken into account. The present experimental result is expressed as R) (0.40 (0.10)-(202 (137)/T (T) 1120-1540 K). Also, in this kinetic analysis, the rate constant of (2) is simultaneously determined to be k 2) 10-11.01(0.33 exp[-(37.8 (8.2) kJ‚mol-1 /RT]. The reaction mechanism of (1) is examined by comparing the experimental results with those of ab initio potential energy surface/transition state theory calculations.
The Journal of Physical Chemistry A, 2003
The rate constant for the reaction S + SO 2 f SO + SO (1) has been investigated by measuring time... more The rate constant for the reaction S + SO 2 f SO + SO (1) has been investigated by measuring time profiles of S atoms behind reflected shock waves using two experimental systems: S atoms were provided by the thermal decomposition of COS in the high-temperature range (2020-2800 K) and by excimer laser photolysis of COS in the low-temperature range (T) 1120-1540 K). The results of these experiments yield the rate constant with a non-Arrhenus temperature dependence, k 1) 10-39.73 T 8.21 exp(4828.5/T) cm 3 molecules-1 s-1 , over the extended temperature range (1120-2800 K). By comparing the rate constants with that derived from a conventional transition-state theory based on the potential energy surface calculated by the G2M-(CC1) methodology, a reaction mechanism including a contribution of the singlet state of the reaction intermediate S 2 O 2 is discussed.
The Journal of Physical Chemistry A, 2004
Shock Waves, 2003
Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the r... more Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the reflected shock of cyclo-C5H6/O2/Ar and C6H5OCH3/O2/Ar mixtures. In both mixtures we could observe the formation of O atoms produced by the reaction of cyclo-C5H5+ O2 → cyclo-C5H5O + O and from the kinetic analysis of these time profiles the rate constant for this reaction was determined to be k = 8.5 × 10 14 exp(−117.0 kJ/RT) cm 3 mol −1 s −1. The possibility of CO formation by the reaction of cyclo-C5H5O → C4H5+ CO was also investigated but because of the subsequent reactions forming CO molecules no direct information for the reaction of cyclo-C5H5O → C4H5+ CO was derived.
International Journal of Quantum Chemistry, 2011
Quantum chemical calculations at the CBS-QB3 level of theory have been carried out to investigate... more Quantum chemical calculations at the CBS-QB3 level of theory have been carried out to investigate the potential energy surfaces for the reactions of aand b-phenylethyl radicals with molecular oxygen. For the a-phenylethyl þ O 2 reaction, all of the transition states for the isomerization reactions of a-phenylethylperoxy radicals were positioned above the total energy of the reactants of a-phenylethyl þ O 2. For the b-phenylethyl þ O 2 reaction, on the other hand, most of the transition states were positioned below the total energy of the reactants of b-phenylethyl þ O 2. The RRKM rate constant analysis revealed that the backward reaction forming a-phenylethyl þ O 2 was dominant in the a-phenylethyl radicals þ O 2 reaction system at the temperature range between 300 and 1500 K, whereas the reaction pathway forming cyclic O 2 structures (5b) was dominant in the b-phenylethyl radicals þ O 2 reaction system at the same temperature range. In the reactions of both aand b-phenylethyl radicals with molecular oxygen, the HO 2 elimination reaction channels became more and more important when
Electrochemical and Solid-State Letters, 2008
Thin-film electrodes were prepared with the laser-ablated BiVO 4 and BiZn 2 VO 6 photocatalytic p... more Thin-film electrodes were prepared with the laser-ablated BiVO 4 and BiZn 2 VO 6 photocatalytic particulates, and the photocurrent action spectra were measured from 350 to 600 nm. The photocurrent of the electrodes prepared from laser-ablated particulates was increased compared to that from nonablated particulates. It was suggested that the increase of the photocurrents for the laser-ablated photocatalytic thin electrode should be attributed to the increase in the surface defect sites on the photocatalytic surface rather than the reduction of the particle size.
Chemistry Letters, 2003
Mechanism of naphthalene (c-C 10 H 8) formation by the recombination of cyclopentadienyl radicals... more Mechanism of naphthalene (c-C 10 H 8) formation by the recombination of cyclopentadienyl radicals (c-C 5 H 5) was investigated by monitoring the time profiles of H atom behind the reflected shock of trifluoromethoxybenzene (C 6 H 5 OCF 3) highly diluted with Ar. The rate constant for cC 5 H 5 + cC 5 H 5 ! cC 10 H 8 + 2H was determined to be 3:3 Â 10 17 exp(À135 kJ/ RT) cm 3 mol À1 s À1 .
Chemistry Letters, 2007
The photocurrent action spectra of S-doped anatase and rutile TiO 2 films were measured in a solu... more The photocurrent action spectra of S-doped anatase and rutile TiO 2 films were measured in a solution of 0.1 M HClO 4 mixed with 0.5 mM of the reductants such as hydroquinone, KI, KSCN, and KBr at the applied voltage of +0.5 V. For the S-doped anatase TiO 2 films, the incident photon to current efficiency (IPCE) was enhanced by the addition of hydroquinone or KI, while no enhancement was observed by the addition of other reductants. On the other hand, the IPCE for the S-doped rutile TiO 2 films was enhanced for all of the reductants. It was suggested that the doped states were different between the Sdoped anatase and rutile TiO 2 films.
Chemical Physics Letters, 2010
OH radicals diffused in the gas phase from the UV-irradiated Pt/TiO2 and WO3/TiO2 photocatalysts ... more OH radicals diffused in the gas phase from the UV-irradiated Pt/TiO2 and WO3/TiO2 photocatalysts have been detected using the laser-induced fluorescence technique. Although the OH-LIF intensities for the Pt/TiO2 photocatalysts increased with increasing amount of Pt, those for the WO3/TiO2 photocatalysts decreased with increasing the amount of WO3. It was also found that the peak positions of the OH-LIF temporal profiles for the Pt/TiO2 and the WO3/TiO2 photocatalysts were slightly shifted compared with that for pure TiO2. Based on these experimental results a mechanism of OH-radical formation from the Pt/TiO2 and WO3/TiO2 photocatalysts was discussed.
Chemical Physics Letters, 2013
Abstract Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have be... more Abstract Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have been performed using the CBS-QB3 method. Based on the potential energy surfaces at the CBS-QB3 level of theory, the preferred reaction channel for the thermal decomposition of 2-phenylethanol was the six-membered cyclic rearrangement reaction and the dehydration reaction to form styrene and H 2 O. Further quantum chemical calculations of the subsequent reactions followed by the six-membered cyclic rearrange reaction of 2-phenylethanol were carried out and it was revealed that the barrier height for the ring opening reaction was the lowest among all of the other subsequent reactions.
Chemical Physics Letters, 2013
The potential energy surfaces for the reaction of 1-naphtylmethyl + O 2 have been calculated usin... more The potential energy surfaces for the reaction of 1-naphtylmethyl + O 2 have been calculated using both of the CBS-QB3 and G3B3 methods. For the 1-naphthlmethyl + O 2 reaction system, the product branching ratios were also calculated using the RRKM/ME analysis and it was found that CH 2 O formation was dominant at temperatures below 500 K. On the other hand, when the temperature became above 500 K, OH radical formation became dominant.
Shock Waves, Sep 1, 2003
Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the r... more Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the reflected shock of cyclo-C5H6/O2/Ar and C6H5OCH3/O2/Ar mixtures. In both mixtures we could observe the formation of O atoms produced by the reaction of cyclo-C5H5+ O2 → cyclo-C5H5O + O and from the kinetic analysis of these time profiles the rate constant for this reaction was determined to be k = 8.5 × 10 14 exp(−117.0 kJ/RT) cm 3 mol −1 s −1. The possibility of CO formation by the reaction of cyclo-C5H5O → C4H5+ CO was also investigated but because of the subsequent reactions forming CO molecules no direct information for the reaction of cyclo-C5H5O → C4H5+ CO was derived.
The Journal of Physical Chemistry, 1993
Absolute concentrations of H atoms and OH radicals were measured to determine the product branchi... more Absolute concentrations of H atoms and OH radicals were measured to determine the product branching ratios for the reactions SiH 3 +O 2 →SiH 2 O+OH (1b) and SiH 3 +O 2 →SiH 2 O 2 +H (1c) by using laser-induced fluorescence (LIF) techniques. The intensity of the VUV-LIF signal of H atoms at Lyman α wavelength was calibrated against the absolute concentration determined by the simultaneous measurement of the Lyman α resonant absorption
SAE Technical Paper Series, 2013
The journal of physical chemistry. A, Jan 13, 2005
The fundamental heat transfer phenomena caused by the 1064 nm pulsed laser irradiations on the mo... more The fundamental heat transfer phenomena caused by the 1064 nm pulsed laser irradiations on the molybdenum aerosol particles were investigated by monitoring the time evolutions of the incandescence spectra using an ICCD detector with a multichannel spectrograph. The particle temperatures were evaluated from the incandescence spectra with the Planck function, and the cooling processes of the laser-heated particles were investigated. By measuring the decrease in the laser-heated particle temperatures with different surrounding media, the roles of the heat transfer processes such as vaporization, thermal radiation, and heat conduction to the surrounding media were discussed. The influences of the vaporization processes on the total heat transfer phenomena were investigated by monitoring the emissions of the constituent molybdenum atoms in the laser-induced incandescence spectra of the aerosol particles and also by investigating the relationships between the intensity of the incandescenc...
ChemInform, 2005
For Abstract see ChemInform Abstract in Full Text.
The Journal of Physical Chemistry C, 2007
Diffusion of OH radicals from UV-irradiated TiO 2 surface to the gas phase was successfully detec... more Diffusion of OH radicals from UV-irradiated TiO 2 surface to the gas phase was successfully detected using a laser-induced-fluorescence technique for various types of TiO 2 powders. The diffusion time of OH radicals was found to vary with the types of TiO 2 powders and to be affected by the heat treatments of these powders, depending on the treatment temperatures. The diffusion mechanism was discussed based on the characteristic OH-LIF intensities for individual TiO 2 powders and the observations of OD-LIF after the exposure of D 2 O vapors over the TiO 2 powders. The quantum yield of OH radicals diffused from the TiO 2 surface was estimated to be about 5 × 10-5 by comparing the OH-LIF intensities produced by the 266-nm photolysis of HNO 3.
The Journal of Physical Chemistry B, 2006
The important roles of OH radicals for remote oxidation using TiO 2 photocatalysts were evidenced... more The important roles of OH radicals for remote oxidation using TiO 2 photocatalysts were evidenced by the in situ detection of OH radicals in the gas phase using the laser-induced fluorescence (LIF) technique. The appearance of OD-LIF intensities after the exposure of D 2 O vapors over TiO 2 powders and the decrease of the time-resolved signals of OH-LIF intensities with increasing calcined temperatures of TiO 2 powders suggested that the exchangeable water at the TiO 2 surface is the origin of the diffused OH radicals.
The Journal of Physical Chemistry A, 2009
Theoretical calculations at the CBS-QB3 level of theory have been performed to investigate the po... more Theoretical calculations at the CBS-QB3 level of theory have been performed to investigate the potential energy surface for the reaction of o-, m-and p-xylyl with molecular oxygen. The differences of the relative potential energies for the products and the transition states of o-, m-and p-xylyl with molecular oxygen were found to be within 8.5 kJ/mol at the CBS-QB3 level of theory. Although the reaction of m-and p-xylyl radicals with molecular oxygen have the same reaction pathways and also the same reaction thermochemistry as that of benzyl radicals, the o-xylylperoxy radicals formed by the reaction of o-xylyl + O 2 had an additional intramolecular isomerization pathway to form the o-xylyl hydroperoxy radicals. The rate constants and the product branching ratios for the o-xylyl + O 2 and its subsequent reactions were evaluated by the RRKM and master equation analysis. Possible roles for these reaction pathways on the combustion of o-xylenes are discussed.
The Journal of Physical Chemistry A, 2007
Ab initio calculations at the level of CBS-QB3 theory have been performed to investigate the pote... more Ab initio calculations at the level of CBS-QB3 theory have been performed to investigate the potential energy surface for the reaction of benzyl radical with molecular oxygen. The reaction is shown to proceed with an exothermic barrierless addition of O 2 to the benzyl radical to form benzylperoxy radical (2). The benzylperoxy radical was found to have three dissociation channels, giving benzaldehyde (4) and OH radical through the four-centered transition states (channel B), giving benzyl hydroperoxide (5) through the six-centered transition states (channel C), and giving O 2-adduct (8) through the four-centered transition states (channel D), in addition to the backward reaction forming benzyl radical and O 2 (channel E). The master equation analysis suggested that the rate constant for the backward reaction (E) of C 6 H 5 CH 2 OO f C 6 H 5 CH 2 + O 2 was several orders of magnitude higher that those for the product dissociation channels (B-D) for temperatures 300-1500 K and pressures 0.1-10 atm; therefore, it was also suggested that the dissociation of benzylperoxy radicals proceeded with the partial equilibrium between the benzyl + O 2 and benzylperoxy radicals. The rate constants for product channels B-D were also calculated, and it was found that the rate constant for each dissociation reaction pathway was higher in the order of channel D > channel C > channel B for all temperature and pressure ranges. The rate constants for the reaction of benzyl + O 2 were computed from the equilibrium constant and from the predicted rate constant for the backward reaction (E). Finally, the product branching ratios forming CH 2 O molecules and OH radicals formed by the reaction of benzyl + O 2 were also calculated using the stationary state approximation for each reaction intermediate.
The Journal of Physical Chemistry A, 2003
The main concern of this study is to investigate the reaction mechanism of O + COS f products (1)... more The main concern of this study is to investigate the reaction mechanism of O + COS f products (1). Experiments are conducted by use of an excimer laser photolysis shock tube technique, where mixtures of COS and SO 2 diluted in Ar are photolyzed behind reflected shock waves. Time-resolved measurements of O and S atoms are conducted by use of atomic resonance absorption spectroscopy, and the overall rate constant of (1) is determined by the O atom decay at temperatures 1250-1600 K, i.e., k 1) 10-10.18(0.26 exp[-(22.5 (7.1) kJ‚mol-1 /RT] cm 3 molecule-1 s-1 , which is in good agreement with the former recommendation. It is confirmed in this experiment that the S atom is a direct product of reaction 1. By analysis of time profiles of the S atom, the branching fraction of the S production channel O + COS f S + CO 2 (1b), R, is determined against the main channel O + COS f CO + SO (1a), where the S atom consumption reactions, S + SO 2 f 2SO (2) and S + COS f S 2 + CO (3), are inevitably taken into account. The present experimental result is expressed as R) (0.40 (0.10)-(202 (137)/T (T) 1120-1540 K). Also, in this kinetic analysis, the rate constant of (2) is simultaneously determined to be k 2) 10-11.01(0.33 exp[-(37.8 (8.2) kJ‚mol-1 /RT]. The reaction mechanism of (1) is examined by comparing the experimental results with those of ab initio potential energy surface/transition state theory calculations.
The Journal of Physical Chemistry A, 2003
The rate constant for the reaction S + SO 2 f SO + SO (1) has been investigated by measuring time... more The rate constant for the reaction S + SO 2 f SO + SO (1) has been investigated by measuring time profiles of S atoms behind reflected shock waves using two experimental systems: S atoms were provided by the thermal decomposition of COS in the high-temperature range (2020-2800 K) and by excimer laser photolysis of COS in the low-temperature range (T) 1120-1540 K). The results of these experiments yield the rate constant with a non-Arrhenus temperature dependence, k 1) 10-39.73 T 8.21 exp(4828.5/T) cm 3 molecules-1 s-1 , over the extended temperature range (1120-2800 K). By comparing the rate constants with that derived from a conventional transition-state theory based on the potential energy surface calculated by the G2M-(CC1) methodology, a reaction mechanism including a contribution of the singlet state of the reaction intermediate S 2 O 2 is discussed.
The Journal of Physical Chemistry A, 2004
Shock Waves, 2003
Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the r... more Oxidation of cyclo-C5H5 was investigated by monitoring O atoms and also CO molecules behind the reflected shock of cyclo-C5H6/O2/Ar and C6H5OCH3/O2/Ar mixtures. In both mixtures we could observe the formation of O atoms produced by the reaction of cyclo-C5H5+ O2 → cyclo-C5H5O + O and from the kinetic analysis of these time profiles the rate constant for this reaction was determined to be k = 8.5 × 10 14 exp(−117.0 kJ/RT) cm 3 mol −1 s −1. The possibility of CO formation by the reaction of cyclo-C5H5O → C4H5+ CO was also investigated but because of the subsequent reactions forming CO molecules no direct information for the reaction of cyclo-C5H5O → C4H5+ CO was derived.
International Journal of Quantum Chemistry, 2011
Quantum chemical calculations at the CBS-QB3 level of theory have been carried out to investigate... more Quantum chemical calculations at the CBS-QB3 level of theory have been carried out to investigate the potential energy surfaces for the reactions of aand b-phenylethyl radicals with molecular oxygen. For the a-phenylethyl þ O 2 reaction, all of the transition states for the isomerization reactions of a-phenylethylperoxy radicals were positioned above the total energy of the reactants of a-phenylethyl þ O 2. For the b-phenylethyl þ O 2 reaction, on the other hand, most of the transition states were positioned below the total energy of the reactants of b-phenylethyl þ O 2. The RRKM rate constant analysis revealed that the backward reaction forming a-phenylethyl þ O 2 was dominant in the a-phenylethyl radicals þ O 2 reaction system at the temperature range between 300 and 1500 K, whereas the reaction pathway forming cyclic O 2 structures (5b) was dominant in the b-phenylethyl radicals þ O 2 reaction system at the same temperature range. In the reactions of both aand b-phenylethyl radicals with molecular oxygen, the HO 2 elimination reaction channels became more and more important when
Electrochemical and Solid-State Letters, 2008
Thin-film electrodes were prepared with the laser-ablated BiVO 4 and BiZn 2 VO 6 photocatalytic p... more Thin-film electrodes were prepared with the laser-ablated BiVO 4 and BiZn 2 VO 6 photocatalytic particulates, and the photocurrent action spectra were measured from 350 to 600 nm. The photocurrent of the electrodes prepared from laser-ablated particulates was increased compared to that from nonablated particulates. It was suggested that the increase of the photocurrents for the laser-ablated photocatalytic thin electrode should be attributed to the increase in the surface defect sites on the photocatalytic surface rather than the reduction of the particle size.
Chemistry Letters, 2003
Mechanism of naphthalene (c-C 10 H 8) formation by the recombination of cyclopentadienyl radicals... more Mechanism of naphthalene (c-C 10 H 8) formation by the recombination of cyclopentadienyl radicals (c-C 5 H 5) was investigated by monitoring the time profiles of H atom behind the reflected shock of trifluoromethoxybenzene (C 6 H 5 OCF 3) highly diluted with Ar. The rate constant for cC 5 H 5 + cC 5 H 5 ! cC 10 H 8 + 2H was determined to be 3:3 Â 10 17 exp(À135 kJ/ RT) cm 3 mol À1 s À1 .
Chemistry Letters, 2007
The photocurrent action spectra of S-doped anatase and rutile TiO 2 films were measured in a solu... more The photocurrent action spectra of S-doped anatase and rutile TiO 2 films were measured in a solution of 0.1 M HClO 4 mixed with 0.5 mM of the reductants such as hydroquinone, KI, KSCN, and KBr at the applied voltage of +0.5 V. For the S-doped anatase TiO 2 films, the incident photon to current efficiency (IPCE) was enhanced by the addition of hydroquinone or KI, while no enhancement was observed by the addition of other reductants. On the other hand, the IPCE for the S-doped rutile TiO 2 films was enhanced for all of the reductants. It was suggested that the doped states were different between the Sdoped anatase and rutile TiO 2 films.
Chemical Physics Letters, 2010
OH radicals diffused in the gas phase from the UV-irradiated Pt/TiO2 and WO3/TiO2 photocatalysts ... more OH radicals diffused in the gas phase from the UV-irradiated Pt/TiO2 and WO3/TiO2 photocatalysts have been detected using the laser-induced fluorescence technique. Although the OH-LIF intensities for the Pt/TiO2 photocatalysts increased with increasing amount of Pt, those for the WO3/TiO2 photocatalysts decreased with increasing the amount of WO3. It was also found that the peak positions of the OH-LIF temporal profiles for the Pt/TiO2 and the WO3/TiO2 photocatalysts were slightly shifted compared with that for pure TiO2. Based on these experimental results a mechanism of OH-radical formation from the Pt/TiO2 and WO3/TiO2 photocatalysts was discussed.
Chemical Physics Letters, 2013
Abstract Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have be... more Abstract Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have been performed using the CBS-QB3 method. Based on the potential energy surfaces at the CBS-QB3 level of theory, the preferred reaction channel for the thermal decomposition of 2-phenylethanol was the six-membered cyclic rearrangement reaction and the dehydration reaction to form styrene and H 2 O. Further quantum chemical calculations of the subsequent reactions followed by the six-membered cyclic rearrange reaction of 2-phenylethanol were carried out and it was revealed that the barrier height for the ring opening reaction was the lowest among all of the other subsequent reactions.
Chemical Physics Letters, 2013
The potential energy surfaces for the reaction of 1-naphtylmethyl + O 2 have been calculated usin... more The potential energy surfaces for the reaction of 1-naphtylmethyl + O 2 have been calculated using both of the CBS-QB3 and G3B3 methods. For the 1-naphthlmethyl + O 2 reaction system, the product branching ratios were also calculated using the RRKM/ME analysis and it was found that CH 2 O formation was dominant at temperatures below 500 K. On the other hand, when the temperature became above 500 K, OH radical formation became dominant.