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Yoshikata Koga - One of the best experts on this subject based on the ideXlab platform.
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spectra of excess Molar Absorptivity of aqueous solutions of ionic liquids universal chromophores for aqueous electrolytes
Journal of Molecular Liquids, 2017Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Abstract We devised a new data analysis methodology for Near Infrared spectroscopic data of aqueous solutions. We first isolate the non-ideal (i.e. real) part of the results as the excess Molar Absorptivity, e E , then define and calculate the excess partial Molar Absorptivity of solute, e S E , the effect of solute (S) on the excess Molar Absorptivity, e E . By using these, we learned that there are three universal chromophores in the ν 2 + ν 3 combination band of H 2 O in the e E spectra of aqueous solutions of the total nine electrolytes. Furthermore, we learned from the excess partial Molar Absorptivity, e S E , we identified a specific chromophore out of three that distinguish the specific characteristics of a given solute on H 2 O. Here we add an evidence for the universality of three bands in e E to include two examples of ionic liquids. In addition, using the literature data, we show that the ν 1 overtone of H 2 O in NaCl – H 2 O and CaCl 2 – H 2 O also have a limited number of universal chromophores at the same wave numbers in their e E spectra.
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spectrum of excess partial Molar Absorptivity part ii a near infrared spectroscopic study of aqueous na halides
Physical Chemistry Chemical Physics, 2012Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Our earlier thermodynamic studies suggested that F− and Cl− form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H2O away from hydration shells unperturbed. Br− and I−, on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H2O, and retard the degree of entropy–volume cross fluctuation inherent in liquid H2O. The effect of the latter is stronger for I− than Br−. Here we seek additional information about this qualitative difference between Cl− and (Br− and I−) pair by near infrared (NIR) spectroscopy. We analyze the ν2 + ν3 band of H2O in the range 4600–5500 cm−1 of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess Molar Absorptivity, eE, excess over the additive contributions of solute and solvent. eE thus contains information about the effect of inter-molecular interactions in the ν2 + ν3 spectrum. The spectrum of eE shows three bands; two negative ones at 5263 and 4873 cm−1, and the positive band at 5123 cm−1. We then define and calculate the excess partial Molar Absorptivity of each salt, eEsalt. From the behaviour of eEsalt we suggest that the negative band at 5263 cm−1 represents free H2O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the xsalt (mole fraction of salt) dependence of eEsalt, we suggest that there is an ion-pairing in xsalt > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of eE at 5123 cm−1 is attributed to a modestly organized hydrogen bond network of H2O (or liquid-likeness), and the xsalt dependence of eEsalt indicated a qualitative difference in the effect of Cl− from those of Br− and I−. Namely, the values of eEsalt stay constant for Cl− but those for Br− and I− decrease smoothly on increasing the salt mole fraction. The mole fraction dependence of eEsalt at the 4873 cm−1 band, due to ice-likeness in H2O, shows a subtle difference between Cl− and (Br−, I−) pair.
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spectrum of excess partial Molar Absorptivity i near infrared spectroscopic study of aqueous acetonitrile and acetone
Journal of Physical Chemistry B, 2009Co-Authors: Yoshikata Koga, Fumie Sebe, Takamasa Minami, Keiko Otake, Kenichi Saitow, Keiko NishikawaAbstract:We study the mixing schemes or the molecular processes occurring in aqueous acetonitrile (ACN) and acetone (ACT) by near-infrared spectroscopy (NIR). Both solutions (any other aqueous solutions) are not free from strong and complex intermolecular interactions. To tackle such a many-body problem, we first use the concept of the excess Molar Absorptivity, eE, which is a function of solute mole fraction in addition to that of wavenumber, ν. The plots of eE calculated from NIR spectra for both aqueous solutions against ν showed two clearly separated bands at 5020 and 5230 cm−1; the former showed negative and the latter positive peaks. At zero and unity mole fractions of solute, eE is identically zero independent of ν. Similar to the thermodynamic excess functions, both negative and positive bands grow in size from zero to the minimum (or the maximum) and back to zero, as the mole fraction varies from 0 to 1. Since the negative band’s ν-locus coincides with the NIR spectrum of ice, and the positive with that o...
Keiko Nishikawa - One of the best experts on this subject based on the ideXlab platform.
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spectra of excess Molar Absorptivity of aqueous solutions of ionic liquids universal chromophores for aqueous electrolytes
Journal of Molecular Liquids, 2017Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Abstract We devised a new data analysis methodology for Near Infrared spectroscopic data of aqueous solutions. We first isolate the non-ideal (i.e. real) part of the results as the excess Molar Absorptivity, e E , then define and calculate the excess partial Molar Absorptivity of solute, e S E , the effect of solute (S) on the excess Molar Absorptivity, e E . By using these, we learned that there are three universal chromophores in the ν 2 + ν 3 combination band of H 2 O in the e E spectra of aqueous solutions of the total nine electrolytes. Furthermore, we learned from the excess partial Molar Absorptivity, e S E , we identified a specific chromophore out of three that distinguish the specific characteristics of a given solute on H 2 O. Here we add an evidence for the universality of three bands in e E to include two examples of ionic liquids. In addition, using the literature data, we show that the ν 1 overtone of H 2 O in NaCl – H 2 O and CaCl 2 – H 2 O also have a limited number of universal chromophores at the same wave numbers in their e E spectra.
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spectrum of excess partial Molar Absorptivity part ii a near infrared spectroscopic study of aqueous na halides
Physical Chemistry Chemical Physics, 2012Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Our earlier thermodynamic studies suggested that F− and Cl− form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H2O away from hydration shells unperturbed. Br− and I−, on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H2O, and retard the degree of entropy–volume cross fluctuation inherent in liquid H2O. The effect of the latter is stronger for I− than Br−. Here we seek additional information about this qualitative difference between Cl− and (Br− and I−) pair by near infrared (NIR) spectroscopy. We analyze the ν2 + ν3 band of H2O in the range 4600–5500 cm−1 of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess Molar Absorptivity, eE, excess over the additive contributions of solute and solvent. eE thus contains information about the effect of inter-molecular interactions in the ν2 + ν3 spectrum. The spectrum of eE shows three bands; two negative ones at 5263 and 4873 cm−1, and the positive band at 5123 cm−1. We then define and calculate the excess partial Molar Absorptivity of each salt, eEsalt. From the behaviour of eEsalt we suggest that the negative band at 5263 cm−1 represents free H2O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the xsalt (mole fraction of salt) dependence of eEsalt, we suggest that there is an ion-pairing in xsalt > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of eE at 5123 cm−1 is attributed to a modestly organized hydrogen bond network of H2O (or liquid-likeness), and the xsalt dependence of eEsalt indicated a qualitative difference in the effect of Cl− from those of Br− and I−. Namely, the values of eEsalt stay constant for Cl− but those for Br− and I− decrease smoothly on increasing the salt mole fraction. The mole fraction dependence of eEsalt at the 4873 cm−1 band, due to ice-likeness in H2O, shows a subtle difference between Cl− and (Br−, I−) pair.
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spectrum of excess partial Molar Absorptivity i near infrared spectroscopic study of aqueous acetonitrile and acetone
Journal of Physical Chemistry B, 2009Co-Authors: Yoshikata Koga, Fumie Sebe, Takamasa Minami, Keiko Otake, Kenichi Saitow, Keiko NishikawaAbstract:We study the mixing schemes or the molecular processes occurring in aqueous acetonitrile (ACN) and acetone (ACT) by near-infrared spectroscopy (NIR). Both solutions (any other aqueous solutions) are not free from strong and complex intermolecular interactions. To tackle such a many-body problem, we first use the concept of the excess Molar Absorptivity, eE, which is a function of solute mole fraction in addition to that of wavenumber, ν. The plots of eE calculated from NIR spectra for both aqueous solutions against ν showed two clearly separated bands at 5020 and 5230 cm−1; the former showed negative and the latter positive peaks. At zero and unity mole fractions of solute, eE is identically zero independent of ν. Similar to the thermodynamic excess functions, both negative and positive bands grow in size from zero to the minimum (or the maximum) and back to zero, as the mole fraction varies from 0 to 1. Since the negative band’s ν-locus coincides with the NIR spectrum of ice, and the positive with that o...
Fumie Sebe - One of the best experts on this subject based on the ideXlab platform.
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spectra of excess Molar Absorptivity of aqueous solutions of ionic liquids universal chromophores for aqueous electrolytes
Journal of Molecular Liquids, 2017Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Abstract We devised a new data analysis methodology for Near Infrared spectroscopic data of aqueous solutions. We first isolate the non-ideal (i.e. real) part of the results as the excess Molar Absorptivity, e E , then define and calculate the excess partial Molar Absorptivity of solute, e S E , the effect of solute (S) on the excess Molar Absorptivity, e E . By using these, we learned that there are three universal chromophores in the ν 2 + ν 3 combination band of H 2 O in the e E spectra of aqueous solutions of the total nine electrolytes. Furthermore, we learned from the excess partial Molar Absorptivity, e S E , we identified a specific chromophore out of three that distinguish the specific characteristics of a given solute on H 2 O. Here we add an evidence for the universality of three bands in e E to include two examples of ionic liquids. In addition, using the literature data, we show that the ν 1 overtone of H 2 O in NaCl – H 2 O and CaCl 2 – H 2 O also have a limited number of universal chromophores at the same wave numbers in their e E spectra.
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spectrum of excess partial Molar Absorptivity part ii a near infrared spectroscopic study of aqueous na halides
Physical Chemistry Chemical Physics, 2012Co-Authors: Fumie Sebe, Keiko Nishikawa, Yoshikata KogaAbstract:Our earlier thermodynamic studies suggested that F− and Cl− form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H2O away from hydration shells unperturbed. Br− and I−, on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H2O, and retard the degree of entropy–volume cross fluctuation inherent in liquid H2O. The effect of the latter is stronger for I− than Br−. Here we seek additional information about this qualitative difference between Cl− and (Br− and I−) pair by near infrared (NIR) spectroscopy. We analyze the ν2 + ν3 band of H2O in the range 4600–5500 cm−1 of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess Molar Absorptivity, eE, excess over the additive contributions of solute and solvent. eE thus contains information about the effect of inter-molecular interactions in the ν2 + ν3 spectrum. The spectrum of eE shows three bands; two negative ones at 5263 and 4873 cm−1, and the positive band at 5123 cm−1. We then define and calculate the excess partial Molar Absorptivity of each salt, eEsalt. From the behaviour of eEsalt we suggest that the negative band at 5263 cm−1 represents free H2O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the xsalt (mole fraction of salt) dependence of eEsalt, we suggest that there is an ion-pairing in xsalt > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of eE at 5123 cm−1 is attributed to a modestly organized hydrogen bond network of H2O (or liquid-likeness), and the xsalt dependence of eEsalt indicated a qualitative difference in the effect of Cl− from those of Br− and I−. Namely, the values of eEsalt stay constant for Cl− but those for Br− and I− decrease smoothly on increasing the salt mole fraction. The mole fraction dependence of eEsalt at the 4873 cm−1 band, due to ice-likeness in H2O, shows a subtle difference between Cl− and (Br−, I−) pair.
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spectrum of excess partial Molar Absorptivity i near infrared spectroscopic study of aqueous acetonitrile and acetone
Journal of Physical Chemistry B, 2009Co-Authors: Yoshikata Koga, Fumie Sebe, Takamasa Minami, Keiko Otake, Kenichi Saitow, Keiko NishikawaAbstract:We study the mixing schemes or the molecular processes occurring in aqueous acetonitrile (ACN) and acetone (ACT) by near-infrared spectroscopy (NIR). Both solutions (any other aqueous solutions) are not free from strong and complex intermolecular interactions. To tackle such a many-body problem, we first use the concept of the excess Molar Absorptivity, eE, which is a function of solute mole fraction in addition to that of wavenumber, ν. The plots of eE calculated from NIR spectra for both aqueous solutions against ν showed two clearly separated bands at 5020 and 5230 cm−1; the former showed negative and the latter positive peaks. At zero and unity mole fractions of solute, eE is identically zero independent of ν. Similar to the thermodynamic excess functions, both negative and positive bands grow in size from zero to the minimum (or the maximum) and back to zero, as the mole fraction varies from 0 to 1. Since the negative band’s ν-locus coincides with the NIR spectrum of ice, and the positive with that o...
Ronald Bartzatt - One of the best experts on this subject based on the ideXlab platform.
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Utilizing UV/VIS Spectrophotometer and Citric
2020Co-Authors: Ronald Bartzatt, Michelle Lee FollisAbstract:Aims: Riboflavin is a B vitamin that is required for a wide variety of cellular processes. The absorbance spectrum of riboflavin was determined at different pH utilizing several buffers. The buffer at pH demonstrating stable absorbance peaks with high numerical values of Molar Absorptivity is followed by accurate and sensitive assay of riboflavin by spectrophotometer. Study design: The absorbance spectrum of riboflavin is determined in an aqueous buffer at various pH values. After identifying the absorbance peaks providing maximal Molar Absorptivity the assay of riboflavin in the identical buffer was undertaken.
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Detection and Assay of Riboflavin (Vitamin B2) Utilizing UV/VIS Spectrophotometer and Citric Acid Buffer
Journal of Scientific Research and Reports, 2014Co-Authors: Ronald BartzattAbstract:Aims: Riboflavinis a B vitamin that is required for a wide variety of cellular processes. The absorbance spectrum of riboflavin was determined at different pH utilizing several buffers. The buffer at pH demon strating stable absorbance peaks with high numerical values of Molar Absorptivity is followed by accurate and sensitive assay of riboflavin by spectrophotometer. Study Design: The absorbance spectrum of riboflavin is determined in an aqueous buffer at various pH values. After identifying the absorbance peaks providing maximal Molar Absorptivity the assay of riboflavin in the identical buffer was undertaken.
Bruce R Weisman - One of the best experts on this subject based on the ideXlab platform.
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a new photometric method for directly determining Molar Absorptivity quantum yield products of excited states application to triplet c60
Chemical Physics Letters, 1998Co-Authors: David A Samuels, Bruce R WeismanAbstract:Abstract A new method is presented for calibrating excited state absorption strengths in terms of absolute densities of excited sample molecules. Beam-imaging photometry measures the profiles of an excitation laser pulse and a collinear probing beam. From these data plus the ground state Absorptivity and the induced absorbance at the probing wavelength, one calculates the product of excited state Molar Absorptivity and formation quantum yield. This photometric method involves no comparison to reference samples. Measurements on the triplet state Absorptivity of C 60 agree closely with recent reports based on comparative methods, suggesting the validity of both approaches.
