Yusuke Morisawa

Publications (13)38.81 Total impact

• Article: Pulse Laser Photolysis of Aqueous Ozone in the Microsecond Range Studied by Time-Resolved Far-Ultraviolet Absorption Spectroscopy.

  Takeyoshi Goto, Yusuke Morisawa, Noboru Higashi, Akifumi Ikehata, Yukihiro Ozaki
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  ABSTRACT: Chemical dynamics of an ozone (O3) pulse-photolytic reaction in aqueous solutions were studied with pump-probe transient far-ultraviolet (FUV) absorption spectroscopy. With a nanosecond pulse laser of 266 nm as pump light, transient spectra of O3 aqueous solutions (78~480 µM, pH 2.5~11.3) were acquired in the time range from -50 to 50 us in the wavelength region from 190 to 225 nm. The measured transient spectra were linearly decomposed into the molar absorption coefficients and the concentration-time profiles of constituted chemical components with a multivariate curve resolution method. From the dependences of the time-averaged concentrations for 20 µs of the constituted chemicals on the initial concentration of O3, it was found that the transient spectra involve the decomposition of O3 and the formation of hydrogen peroxide (H2O2) and a third component that is assigned to hydroxyl radical (OH) or perhydroxyl radical (HO2). Furthermore, the pH dependence of the time-averaged concentration of the third components indicates that HO2 is more probable than OH as the third component. The time-averaged concentration ratio of each chemical component to the initial O3 concentration depends on the pH conditions from -0.95 to -0.60 for O3, 0.98 to 1.2 for H2O2, 0.002 to 0.29 for OH, and 0.012 to 0.069 for HO2.
  Analytical Chemistry 04/2013; · 5.86 Impact Factor
• Article: Electronic Transitions of Protonated and Deprotonated Amino Acids in Aqueous Solution in the Region 145-300 nm Studied by Attenuated Total Reflection Far-Ultraviolet Spectroscopy.

  Takeyoshi Goto, Akifumi Ikehata, Yusuke Morisawa, Yukihiro Ozaki
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  ABSTRACT: The electronic transitions of 20 naturally occurring amino acids in aqueous solution were studied with attenuated total reflection far-ultraviolet (ATR-FUV) spectroscopy in the region from 145 to 300 nm. From the measured ATR spectra of sample solutions, the FUV absorption spectra attributed to the amino acids were separated from the intense solvent absorption by using a modified Kramers-Kronig transformation method. The FUV absorption spectra of the amino acids reflect the protonated states of the backbone and side-chain structures. The contributions of the side-chains to the spectra were also examined from the difference spectra subtracting the corresponding Gly spectrum from each spectrum. The observed spectra were compared mostly with the electronic transition studies of the molecular fragments of the amino acids in gas phase. The FUV spectra of the amino acids exhibited the intra- and inter-molecular electronic interactions of the solute-solute as well as the solute-solvent, and those are essential factors to elucidate UV photochemical processes of the amino acids in aqueous solution.
  The Journal of Physical Chemistry A 03/2013; · 2.95 Impact Factor
• Article: Quantum Mechanical Interpretation of Intermolecular Vibrational Modes of Crystalline Poly-(R)-3-Hydroxybutyrate Observed in Low-Frequency Raman and THz Spectra.

  Shigeki Yamamoto, Yusuke Morisawa, Harumi Sato, Hiromichi Hoshina, Yukihiro Ozaki
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  ABSTRACT: Low-frequency vibrational bands observed in Raman and THz spectra in the region of 50-150 cm(-1) of crystalline powder poly-(R)-3-hydroxybutyrate (PHB) were assigned based on comparisons of the Raman and THz spectra, polarization directions of THz absorption spectra, and their congruities to quantum-mechanically (QM) calculated spectra. This combination, Raman and THz spectroscopies and the QM simulations, has been rarely adopted in spite of its potential of more reliable assignments of the vibrational bands. The QM simulation of a spectrum has already been popular in vibrational spectroscopies, but for low-frequency bands of polymers it is still a difficult task due to its large scales of systems and a fact that interactions among polymer chains should be considered in the calculation. In this study the spectral calculations with the aid of the Cartesian-coordinate tensor transfer (CCT) method were applied successfully to the crystalline PHB, which include the explicit consideration of an intermolecular interaction among helical polymer chains. The agreements between the calculations and the experiments are good in both of the Raman and THz spectra in terms of spectral shapes, frequencies, and intensities. A Raman active band at 79 cm(-1) was assigned to the intermolecular vibrational mode of the out-of-plane C=O+CH(3) vibration. A polarization state of the corresponding far-infrared absorption band at ~82 cm(-1), perpendicular to the helix-elongation direction of PHB, was reproduced only under the explicit correction, which indicates that this polarized band originates from the interaction among the polymer chains. The calculation explored that the polarization direction of this band was along the a axis, which is consistent with the direction where weak intermolecular hydrogen bonds are suggested between the C=O and CH(3) groups of two parallel polymer chains. The results obtained here have confirmed sensitivity of the low-frequency vibrational bands to the weak hydrogen bonds among the polymer chains.
  The Journal of Physical Chemistry B 01/2013; · 3.70 Impact Factor
• Article: Elucidating Electronic Transitions from σ Orbitals of Liquid n- and Branched Alkanes by Far-Ultraviolet Spectroscopy and Quantum Chemical Calculations.

  Yusuke Morisawa, Shin Tachibana, Masahiro Ehara, Yukihiro Ozaki
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  ABSTRACT: Attenuated total reflection far-ultraviolet (ATR-FUV) spectra containing Rydberg states of n-alkanes (CnH2n+1; n varies in the range 5-9) and branched alkanes observed in the liquid phase were investigated by quantum chemical calculations with the aim of elucidating electronic transitions from σ orbitals of liquid n- and branched alkanes. New assignments are proposed based on the time-dependent density functional theory (TD-DFT) and symmetry-adapted cluster configuration interaction (SAC-CI) calculations, and the differences in these spectra are analyzed in detail. The FUV spectra of n-alkanes show a broad asymmetric feature near 8.3 eV. The strong band at ~8.3 eV shows a red shift with a significant increase in intensity as the carbon chain length increases, which is attributed to the overlapping transitions from the third (or fourth) highest occupied molecular orbitals HOMO-2 (or HOMO-3) and HOMO-1 to Rydberg 3py by the TD-DFT and SAC-CI calculations. Although the most intense transition, T1, is from HOMO-2 for n = 5 and 6 and HOMO-3 for n varying in the range of 7-9, the shape of Kohn-Sham molecular orbital for T1 is similar among the all alkanes investigated. The theoretical result also has demonstrated that the red shift originates in both stabilization of the Rydberg 3py and destabilization of the occupied orbitals. The intensity of the shoulder at 7.7 eV drastically increases in the spectra of the branched alkanes, especially for those with quaternary carbon atoms such as 2,2-dimethyl butane. This increase in intensity is caused by a reduction in symmetry in the branched alkanes, which leads the forbidden transitions to Rydberg 3s to allowed transitions. In this way the present study has provided new insight into the existence of their Rydberg transitions and the shape of the relevant MOs of the transitions.
  The Journal of Physical Chemistry A 11/2012; · 2.95 Impact Factor
• Article: Development of a time-resolved attenuated total reflectance spectrometer in far-ultraviolet region.

  Yusuke Morisawa, Noboru Higashi, Kyoko Takaba, Naomi Kariyama, Takeyoshi Goto, Akifumi Ikehata, Yukihiro Ozaki
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  ABSTRACT: A far-ultraviolet transient absorption spectrometer based on time-resolved attenuated total reflectance (ATR) has been developed and tested for aqueous solutions of phenol and tryptophan in the region 170-185 nm. In this region, a stable tunable laser was not available, and therefore, white light from a laser-driven Xe lamp source was used. The time resolution, which was determined by the time response of a continuous light detector, was 40 ns. A new ATR cell where a sample liquid is exchanged continuously by a flow system was designed to reduce efficiently the stray light from the excitation light. We have tested the performance of the instrument by using aqueous solutions of phenol and tryptophan, whose photochemistry is already well known. Phenol and tryptophan have very strong absorptions due to a π-π∗ transition near 180 nm. Even for dilute solutions (10(-3) mol dm(-3)), we could observe decreases in their concentrations due to photochemistry that occurred upon their irradiation with a fourth harmonic generation laser pulse produced by an Nd:YAG laser. The sensitivity of the spectrometer was about 10(-4) abs, which corresponded to a concentration variation of 10(-3) mol dm(-3) for phenol and tryptophan.
  The Review of scientific instruments 07/2012; 83(7):073103. · 1.52 Impact Factor
• Article: The effect of metal cations on the nature of the first electronic transition of liquid water as studied by attenuated total reflection far-ultraviolet spectroscopy.

  Takeyoshi Goto, Akifumi Ikehata, Yusuke Morisawa, Noboru Higashi, Yukihiro Ozaki
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  ABSTRACT: The first electronic transition (Ã←X̃) of liquid water was studied from the perspective of the hydration of cations by analyzing the attenuated total reflection far-ultraviolet (ATR-FUV) spectra of the Group I, II, and XIII metal nitrate electrolyte solutions. The Ã←X̃ transition energies of 1 M electrolyte solutions are higher (Li(+): 8.024 eV and Cs(+): 8.013 eV) than that of pure water (8.010 eV) and linearly correlate with the Gibbs energies of hydration of the cations. The increases in the Ã←X̃ transition energies are mostly attributable to the hydrogen bond formation energies of water molecules in the ground state induced by the presence of the cations. The deviation from the linear relation was observed for the high charge density cations, H(+), Li(+), and Be(2+), which reflects that the electronic energies in the excited states are also perturbed. Quantum chemical calculations show that the Ã←X̃ transition energies of the water-cation complexes depend on the hydration structures of the cations. The calculated Ã←X̃ transition energies of the water molecules hydrating high charge density cations spread more widely than those of the low charge density cations. The calculated transition energy spreads of the water-cation complexes directly correlate with the widths of the Ã←X̃ transition bands measured by ATR-FUV spectroscopy.
  Physical Chemistry Chemical Physics 05/2012; 14(22):8097-104. · 3.57 Impact Factor
• Article: Far-Ultraviolet Spectroscopy in the Solid and Liquid States: A Review

  Yukihiro Ozaki, Yusuke Morisawa, Akifumi Ikehata, Noboru Higashi
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  ABSTRACT: Ultraviolet (UV) spectroscopy has long been used together with visible (Vis) spectroscopy to investigate electronic transitions of a molecule. Most studies of the electronic structure of molecules using UV spectroscopy have been carried out in the 190-380 nm region because commercial UV-Vis spectrometers are available only for that region. The wavelength region shorter than 190 nm is also very rich in information about the electronic states and structure of a molecule, but the absorptivity is very high in this region, and thus, this region has been employed to investigate mainly the electronic states and structure of gas molecules. Because condensed-phase materials with high molecular density do not transmit much light in the shorter wavelength region of the UV, reflection spectroscopy has been used to observe spectra of solid samples in the wavelength region shorter than 190 nm. However, for liquid samples one cannot generally use either absorption spectroscopy or specular reflection spectroscopy. Accordingly, UV spectroscopy in this region for liquid samples has been a relatively undeveloped research area. To solve the above difficulties of UV spectroscopy in the wavelength region shorter than 190 nm we have recently developed a totally new UV spectrometer based on attenuated total reflection (ATR) that enables us to measure spectra of liquid and solid samples in the 140-280 nm region. We will show that spectroscopy in the wavelength region shorter than 190 nm holds considerable promise not only in basic science but also in applications such as qualitative and quantitative analysis, on-line monitoring, environmental geochemical analysis, and surface analysis. The purpose of the present review paper is to report recent progress in UV spectroscopy of solid and liquid phases in the 140-280 nm region. In this review, we refer to the 120-200 nm region to as the far-UV (FUV) region. The term “vacuum UV region“ is no longer appropriate for the 120-200 nm region because most recent spectrometers used in this region are not evacuated but instead incorporate a nitrogen purge. This review consists of eight parts: (1) introduction to FUV spectroscopy, (2) brief history of FUV spectroscopy, (3) development of new FUV spectrometers, (4) FUV studies of liquid water and aqueous solutions, (5) FUV spectra of organic molecules in the liquid states, (6) band assignments by quantum chemical calculations, (7) potential applications of FUV spectroscopy in liquid and solid states; and (8) future prospects of FUV spectroscopy.
  Applied Spectroscopy 12/2011; 66:1-25. · 1.66 Impact Factor
• Article: Hydrogen bonding effects on the wavenumbers and absorption intensities of the OH fundamental and the first, second, and third overtones of phenol and 2,6-dihalogenated phenols studied by visible/near-infrared/infrared spectroscopy.

  Takayuki Gonjo, Yoshisuke Futami, Yusuke Morisawa, Marek J Wojcik, Yukihiro Ozaki
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  ABSTRACT: Visible, near-infrared (NIR) and IR spectra in the 15600-2500 cm(-1) region were measured for phenol and 2,6-difluorophenol, 2,6-dichlorophenol, and 2,6-dibromophenol in n-hexane, CCl(4), CHCl(3) and CH(2)Cl(2) to study hydrogen bonding effects and solvent dependences of wavenumbers and absorption intensities of the fundamental and the first, second, and third overtones of OH stretching vibrations. A band shift of the OH stretching vibrations from a gas state to a solution state (solvent shift) was plotted versus vibrational quantum number (v = 0, 1, 2 and 3), and it was found that there is a linear relation between the solvent shift and the vibrational quantum number. The slope of solvent shift decreases in the order of phenol, 2,6-difluorophenol and 2,6-dichlorophenol. For all of the solute molecules, the slope becomes larger with the increase in the dielectric constant of the solvents. The relative intensities of the OH stretching vibrations of phenol in CCl(4), CHCl(3), and CH(2)Cl(2) against the intensity of the corresponding OH vibration in n-hexane increase in the fundamental and the second overtone but decrease in the first and third overtones; the relative intensities show so-called "parity". The parity is more prominent for phenol that has an intermolecular hydrogen bonding than for 2,6-dihalogenated phenols that have an intramolecular hydrogen bond. These observations suggest that the intermolecular hydrogen bond between the OH group and the Cl atom plays a key role for the parity and that the intermolecular interaction between the solutes and the solvents (solvent effects) does not have a significant role in the parity.
  The Journal of Physical Chemistry A 08/2011; 115(35):9845-53. · 2.95 Impact Factor
• Article: Polarization and temperature dependent spectra of poly(3-hydroxyalkanoate)s measured at terahertz frequencies.

  Hiromichi Hoshina, Yusuke Morisawa, Harumi Sato, Hiroaki Minamide, Isao Noda, Yukihiro Ozaki, Chiko Otani
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  ABSTRACT: Temperature-dependent terahertz (THz) absorption spectra of poly(3-hydroxyalkanoate)s (PHAs) were measured by using a Fourier transform far-infrared (FT-FIR) spectrometer and a THz time-domain spectrometer over a temperature range of 10 K to 465 K with a liquid helium cryostat and a heating cell. Clear differences were observed between the spectra of crystalline and amorphous polyhydroxybutyrate (PHB), indicating that the absorption peaks observed in the THz spectra originated in the higher-order conformation of PHB. The polarization spectra of a stretched PHB sample were measured, and the direction of the vibrational transition moment was determined. The temperature dependences of the spectra reveal frequency shifts and broadening of the absorption peaks with temperature, suggesting large anharmonicity of the vibrational potential. The temperature shift behaviour is quite different in each transition. Some of the transitions show a blue shift, which cannot be explained by a simple anharmonic potential model. Frequency shifts of the peaks were mainly observed below 10 THz, which suggests a large anharmonicity of the vibrational potential at lower frequencies.
  Physical Chemistry Chemical Physics 04/2011; 13(20):9173-9. · 3.57 Impact Factor
• Article: Low-n Rydberg transitions of liquid ketones studied by attenuated total reflection far-ultraviolet spectroscopy.

  Yusuke Morisawa, Akifumi Ikehata, Noboru Higashi, Yukihiro Ozaki
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  ABSTRACT: Far-ultraviolet (FUV) spectra in the 8.55-6.20 eV (145-200 nm) region were measured for several kinds of ketones in the liquid phase to investigate low-n Rydberg transitions using a uniquely developed technique of attenuated total reflection (ATR) FUV spectrometry. Assignments of the transitions are attempted for absorptions in this region by comparing the spectra for the liquid phase with those for the gas phase and ab initio calculations at the equation-of-motion coupled cluster theory with single and double substitutions at the aug-cc-pVDZ level. The transition from a nonbonding electron (n) to the 3s Rydberg orbital was found at around 6.7 eV for all investigated liquid ketones. Another intense band also appeared in the higher-energy region (ca. 8.5 eV) for all the ketones. A significant shoulder was found at around 7.4 eV for branched ketones. This shoulder band near 7.4 eV was assigned to the n-3p Rydberg transition. Band broadening and higher energy shifts were observed in the spectra of the liquid phase ketones in comparison with those of the gas phase ketones.
  The Journal of Physical Chemistry A 02/2011; 115(5):562-8. · 2.95 Impact Factor
• Article: Quantitative analysis of ions in spring water in three different areas of Hyogo Prefecture in Japan by far ultraviolet spectroscopy.

  Motoki Mitsuoka, Hideyuki Shinzawa, Yusuke Morisawa, Naomi Kariyama, Noboru Higashi, Motohiro Tsuboi, Yukihiro Ozaki
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  ABSTRACT: Far-ultraviolet (FUV) spectra in the 190-300 nm region were measured for spring water in Awaji-Akashi area, Tamba area and Rokko-Arima area in Hyogo Prefecture, Japan, these areas have quite different geology features. The spectra of the spring water in the Awaji-Akashi area can be divided into two groups: the spring water samples containing large amounts of NO(3)(-) and/or Cl(-), and those containing only small amounts of NO(3)(-) and Cl(-). The former shows a saturated band below 190 nm due to NO(3)(-) and/or Cl(-). These two types of spectra correspond to different lithological areas: sedimentary lithology near the sea shore containing many ions in the seawater and gravitic lithology far from the sea side, in the Awaji-Akashi area. The spring water from the Tamba area, which is far from the sea, contains relatively small amounts of NO(3)(-) and Cl(-); it does not yield a strong band in the region observed. The FUV spectra of three of four kinds of spring water samples in the Arima Hotspring show characteristic spectral patterns. They are quite different from the spectra of the spring water samples of the Rokko area. Calibration models were developed for NO(3)(-), Cl(-), SO(4)(2-), Na(+), and Mg(2+) in the nine kinds of spring water collected in the Awaji-Akashi area, Tamba, and Rokko-Arima area by using univariate analysis of the first derivative spectra and the actual values obtained by ion chromatography. NO(3)(-) yields the best results: correlation coefficient of 0.999 and standard deviation of 0.09 ppm with the wavelength of 212 nm. Cl(-) also gives good results: correlation coefficient of 0.993 and standard deviation of 0.5 ppm with the wavelength of 192 nm.
  Analytical Sciences 01/2011; 27(2):177-82. · 1.25 Impact Factor
• Article: Effect of cations on absorption bands of first electronic transition of liquid water.

  Akifumi Ikehata, Motoki Mitsuoka, Yusuke Morisawa, Naomi Kariyama, Noboru Higashi, Yukihiro Ozaki
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  ABSTRACT: The effect of cations (Li(+), Na(+), K(+), Rb(+), and Cs(+)) on the first electronic transition (A <-- X) of liquid water was investigated by attenuated total reflection far ultraviolet spectroscopy. To negate the effect of anions, aqueous solutions of 1 M alkali metal nitrates and bromides were compared at a temperature of 25 degrees C. It is found that the peak energy of the A <-- X band of water, which shows a marked red shift with decreasing hydrogen-bond strength, decreases with increasing cation size. The peak energies of the A <-- X band can be approximated by a linear function of the inverse of the ionic radii of the alkali metal cations, which indicates (according to the Born equation) that the first electronic transition of water is characterized by the solvation energy of the cations.
  The Journal of Physical Chemistry A 08/2010; 114(32):8319-22. · 2.95 Impact Factor
• Article: Photodissociation dynamics of 2,5-dihydroxyacetophenone.

  Yusuke Morisawa, Yuri A Dyakov, Chien-Ming Tseng, Y T Lee, Chi-Kung Ni
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  ABSTRACT: Photodissociation of 2,5-dihydroxyacetophenone (DHAP), an important matrix compound in matrix-assisted laser desorption/ionization (MALDI), was studied in a molecular beam at 193 nm using multimass ion imaging techniques. Two major dissociation channels were observed, including (1) C(6)H(3)(OH)(2)COCH(3) --> OC(6)H(3)(OH)COCH(3) + H and (2) C(6)H(3)(OH)(2)COCH(3) --> C(6)H(3)(OH)(2) + COCH(3). The minor channels include C(6)H(3)(OH)(2)COCH(3) --> C(6)H(3)(OH)(2)CO + CH(3) and/or C(6)H(3)(OH)(2)COCH(3) --> C(6)H(3)(OH)(2) + CO + CH(3). The photofragment translational energy distribution suggests that reaction 1 occurs at an excited state in which the potential along the O-H bond distance is repulsive. Comparison to the branching ratios from RRKM calculations suggests that reaction 2 does not occur at either the ground state or the triplet state or that if it does occur at one of these states it must not follow the RRKM model. A comparison to the photodissociation dynamics of acetophenone and phenol and its derivatives was made.
  The Journal of Physical Chemistry A 01/2009; 113(1):97-102. · 2.95 Impact Factor