Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand ... more Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (203 Tl and 205 Tl) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ionexchange chemistry, the isotope ratio of 205 Tl/ 203 Tl in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation >1 ‰ was found. Electronic structures of possible Tl species (hydrated Tl + , Tl 3+ , and Tl chlorides) were calculated by ab initio methods, and the isotope fractionation factor was theoretically obtained. The isotope fractionation via intramolecular vibrations was calculated to be much smaller than the experimental result. The isotope fractionation via isotopic change in nuclear volume, named the nuclear field shift effect, was calculated to be >1 ‰ in Tl(I)-Tl(III) redox systems and/or ligand exchange systems of Tl(III). The nuclear field shift effect was found to be the major origin of Tl isotope fractionation.
In search of suitable molecular candidates for probing the electric dipole moment (EDM) of the el... more In search of suitable molecular candidates for probing the electric dipole moment (EDM) of the electron (de), a property that arises due to parity and time-reversal violating (P,T-odd) interactions, we consider the triatomic mercury hydroxide (HgOH) molecule. The impetus for this proposal is based on previous works on two systems: the recently proposed ytterbium hydroxide (YbOH) experiment that demonstrates the advantages of polyatomics for such EDM searches, and the finding that mercury halides provide the highest enhancement due to de compared to other diatomic molecules. We identify the ground state of HgOH as being in a bent geometry, and show that its intrinsic EDM sensitivity is comparable to the corresponding value for YbOH. Along with the theoretical results, we discuss plausible experimental schemes for an EDM measurement in HgOH. Furthermore, we provide pilot calculations of the EDM sensitivity for de for HgCH3 and HgCF3, that are natural extensions of HgOH.
Diatomic polar molecules have been the focus of research in the recent past as candidates for ele... more Diatomic polar molecules have been the focus of research in the recent past as candidates for electron electric dipole moment (eEDM), d e , measurements. In the present work, we focus on RaH molecule and have calculated three of its properties (in the X 2 + state) the effective electric field (E eff), the scalar-pseudoscalar (S-PS) interaction coefficient (W s,A), and permanent electric dipole moment (PDM) that play crucial roles in probing fundamental symmetry violations. The calculations were based on the relativistic coupled-cluster singles and doubles (RCCSD) frame work. Our results for |E eff |, W s,A , and PDM are 80.31 GV/cm, 216.82 kHz, and 4.44 D respectively. In addition to possessing high magnitudes of E eff and W s,A , RaH also has a large PDM, which is a highly desirable criterion for eEDM experiments. The analysis of our results clearly indicates the spectacular role of electron correlation in enhancing their magnitudes ≈16% for PDM and ≈31% for E eff and W s,A. The ratio of E eff to W s,A for RaH is 89.56 × 10 18 e −1 cm −1. Based on our results and other experimental considerations, we propose RaH as a future candidate for experiments in this field.
We analyze the relativistic effects of the hyperfine coupling constant (HFCC) by using the soluti... more We analyze the relativistic effects of the hyperfine coupling constant (HFCC) by using the solutions of the Dirac and Schrödinger equations of Hydrogen-like atoms. We find that the relativistic effects of HFCC of the ground states of the Hydrogen-like atoms (Z = 30, 40) are about 8% and 15%, respectively.
methodologies beyond the born-Oppenheimer (bO) approximation are nowadays important to explain hi... more methodologies beyond the born-Oppenheimer (bO) approximation are nowadays important to explain high precision spectroscopic measurements. Our work is the first development and application of the diagonal BO correction (DBOC) based on spin-free relativistic Hamiltonians. We used the second and infinite-order Douglas-Kroll-Hess Hamiltonians at their spin-free levels. Our test calculations of noble atoms (he-Xe) show that the dbOc energy (edbOc) is approximately proportional to atomic number Z. hence the bO correction generally increases when a molecule contains heavier atoms. We also computed the adiabatic corrections to the barrier heights for linearization of h 2 X molecules where X = O, S, Se, and te, to discuss dbOc corrections for heavy elements.
In this study, we present a density functional study of four ruthenium complexes by means of UV−v... more In this study, we present a density functional study of four ruthenium complexes by means of UV−visible spectroscopy and Marcus theory. These molecules, [Ru II (bipyP)(bipy) 2 ] (P1), [Ru II (bipyP)(dmb) 2 ] (P2), [Ru II (bipyP)(dtbb) 2 ] (P3), and [Ru II (bipyP)(dnb) 2 ] (P4), where bipyP = 2,2′-bipyridine-4,4′diphosphonic acid, bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine, dtbb = 4,4′-di-tert-butyl-2,2′-bipyridine, and dnb = 4,4′-dinonyl-2,2′-bipyridine, are photosensitizers for applications in dye-sensitized photo-electrochemical cells (DSPECs). Because of the undetermined P4 conformation in the experiment, we modeled three P4 conformers with straight (P4-straight) and bent nonyl chains (P4-bend1 and bend2). UV−vis absorption spectra by timedependent density functional theory showed intense metal-toligand charge transfer to anchor bipyridine ligands (MLCT-anchoring) at 445−460 nm, which accurately reproduce experimental data. The largest light-harvesting efficiency of the MLCT-anchoring state was observed in the P4-bend1 conformer, which has the lowest P4 energy. This may relate to greater electron injection in the P4 and supports experimental results of dye-only systems (do-DSPEC). The calculated charge transfer rates agree well with the experimental trend. The largest rate was obtained for P2, which was attributed to the expansion of the highest-occupied molecular orbital toward the ancillary bipy ligands and also to the short distances between dyes on the TiO 2 surface. These results also support experimental results for P2, which was the best compound for lateral hole-hopping in a sacrificial agent-containing system (sa-DSPEC).
The relativistic coupled-cluster (RCC) theory has been applied recently to a number of heavy mole... more The relativistic coupled-cluster (RCC) theory has been applied recently to a number of heavy molecules to determine their properties very accurately. Since it demands large computational resources, the method is often approximated to single and double excitations (RCCSD method). The effective electric fields ( E e f f ) and molecular permanent electric dipole moments (PDMs) of SrF, BaF, and mercury monohalides (HgX with X = F, Cl, Br, and I) molecules are of immense interest for probing fundamental physics. In our earlier calculations of E e f f and PDMs for the above molecules, we neglected the non-linear terms in the property evaluation expression of the RCCSD method. In this work, we demonstrate the roles of these terms in determining the above quantities and their computational time scalability with the number of processors of a computer. We also compare our results with previous calculations that employed variants of RCC theory, as well as other many-body methods and available ...
The dye-sensitized photoelectrochemical cells (DSPECs) incorporating a family of ruthenium comple... more The dye-sensitized photoelectrochemical cells (DSPECs) incorporating a family of ruthenium complexes [RuII(bipyP)(bipy)2] (P1), [RuII(bipyP)(dmb)2] (P2), [RuII(bipyP)(dtbb)2] (P3) and [RuII(bipyP)(dnb)2] (P4) where bipyP = 2,2'-bipyridine-4,4'-diphosphonic acid; bipy = 2,2'-bipyridine; dmb =...
Transition frequencies of cold molecules must be accurately evaluated to test the variance in the... more Transition frequencies of cold molecules must be accurately evaluated to test the variance in the protonto-electron mass ratio. Measuring the X 2 (v,N) = (0,0) → (1,0) transition frequency of optically trapped 174 Yb 6 Li molecules is a promising method for achieving this goal. The Stark shifts induced by trap and probe (for the Raman transition) lasers are eliminated by choosing appropriate frequencies (magic frequencies) during the construction of the optical lattice. In the far-off resonance region, the Stark shift is found to be less than 10 −16 even when the laser frequencies are detuned from the magic frequencies by ∼1 MHz.
The journal of physical chemistry. A, Jan 29, 2016
Methodologies beyond the Born-Oppenheimer (BO) approximation are nowadays important to explain hi... more Methodologies beyond the Born-Oppenheimer (BO) approximation are nowadays important to explain high precision spectroscopic measurements. Most previous evaluations of the BO correction are, however, focused on light-element molecules and based on a nonrelativistic Hamiltonian, so no information about the BO approximation (BOA) breakdown in heavy-element molecules is available. The present work is the first to investigate the BOA breakdown for the entire periodic table, by considering scalar relativistic effects in the Diagonal BO correction (DBOC). In closed shell atoms, the relativistic EDBOC scales as Z(1.25) and the nonrelativistic EDBOC scales as Z(1.17), where Z is the atomic number. Hence, we found that EDBOC becomes larger in heavy element atoms and molecules, and the relativistic EDBOC increases faster than nonrelativistic EDBOC. We have further investigated the DBOC effects on properties such as potential energy curves, spectroscopic parameters, and various energetic proper...
Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand ... more Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (203 Tl and 205 Tl) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ionexchange chemistry, the isotope ratio of 205 Tl/ 203 Tl in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation >1 ‰ was found. Electronic structures of possible Tl species (hydrated Tl + , Tl 3+ , and Tl chlorides) were calculated by ab initio methods, and the isotope fractionation factor was theoretically obtained. The isotope fractionation via intramolecular vibrations was calculated to be much smaller than the experimental result. The isotope fractionation via isotopic change in nuclear volume, named the nuclear field shift effect, was calculated to be >1 ‰ in Tl(I)-Tl(III) redox systems and/or ligand exchange systems of Tl(III). The nuclear field shift effect was found to be the major origin of Tl isotope fractionation.
In search of suitable molecular candidates for probing the electric dipole moment (EDM) of the el... more In search of suitable molecular candidates for probing the electric dipole moment (EDM) of the electron (de), a property that arises due to parity and time-reversal violating (P,T-odd) interactions, we consider the triatomic mercury hydroxide (HgOH) molecule. The impetus for this proposal is based on previous works on two systems: the recently proposed ytterbium hydroxide (YbOH) experiment that demonstrates the advantages of polyatomics for such EDM searches, and the finding that mercury halides provide the highest enhancement due to de compared to other diatomic molecules. We identify the ground state of HgOH as being in a bent geometry, and show that its intrinsic EDM sensitivity is comparable to the corresponding value for YbOH. Along with the theoretical results, we discuss plausible experimental schemes for an EDM measurement in HgOH. Furthermore, we provide pilot calculations of the EDM sensitivity for de for HgCH3 and HgCF3, that are natural extensions of HgOH.
Diatomic polar molecules have been the focus of research in the recent past as candidates for ele... more Diatomic polar molecules have been the focus of research in the recent past as candidates for electron electric dipole moment (eEDM), d e , measurements. In the present work, we focus on RaH molecule and have calculated three of its properties (in the X 2 + state) the effective electric field (E eff), the scalar-pseudoscalar (S-PS) interaction coefficient (W s,A), and permanent electric dipole moment (PDM) that play crucial roles in probing fundamental symmetry violations. The calculations were based on the relativistic coupled-cluster singles and doubles (RCCSD) frame work. Our results for |E eff |, W s,A , and PDM are 80.31 GV/cm, 216.82 kHz, and 4.44 D respectively. In addition to possessing high magnitudes of E eff and W s,A , RaH also has a large PDM, which is a highly desirable criterion for eEDM experiments. The analysis of our results clearly indicates the spectacular role of electron correlation in enhancing their magnitudes ≈16% for PDM and ≈31% for E eff and W s,A. The ratio of E eff to W s,A for RaH is 89.56 × 10 18 e −1 cm −1. Based on our results and other experimental considerations, we propose RaH as a future candidate for experiments in this field.
We analyze the relativistic effects of the hyperfine coupling constant (HFCC) by using the soluti... more We analyze the relativistic effects of the hyperfine coupling constant (HFCC) by using the solutions of the Dirac and Schrödinger equations of Hydrogen-like atoms. We find that the relativistic effects of HFCC of the ground states of the Hydrogen-like atoms (Z = 30, 40) are about 8% and 15%, respectively.
methodologies beyond the born-Oppenheimer (bO) approximation are nowadays important to explain hi... more methodologies beyond the born-Oppenheimer (bO) approximation are nowadays important to explain high precision spectroscopic measurements. Our work is the first development and application of the diagonal BO correction (DBOC) based on spin-free relativistic Hamiltonians. We used the second and infinite-order Douglas-Kroll-Hess Hamiltonians at their spin-free levels. Our test calculations of noble atoms (he-Xe) show that the dbOc energy (edbOc) is approximately proportional to atomic number Z. hence the bO correction generally increases when a molecule contains heavier atoms. We also computed the adiabatic corrections to the barrier heights for linearization of h 2 X molecules where X = O, S, Se, and te, to discuss dbOc corrections for heavy elements.
In this study, we present a density functional study of four ruthenium complexes by means of UV−v... more In this study, we present a density functional study of four ruthenium complexes by means of UV−visible spectroscopy and Marcus theory. These molecules, [Ru II (bipyP)(bipy) 2 ] (P1), [Ru II (bipyP)(dmb) 2 ] (P2), [Ru II (bipyP)(dtbb) 2 ] (P3), and [Ru II (bipyP)(dnb) 2 ] (P4), where bipyP = 2,2′-bipyridine-4,4′diphosphonic acid, bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine, dtbb = 4,4′-di-tert-butyl-2,2′-bipyridine, and dnb = 4,4′-dinonyl-2,2′-bipyridine, are photosensitizers for applications in dye-sensitized photo-electrochemical cells (DSPECs). Because of the undetermined P4 conformation in the experiment, we modeled three P4 conformers with straight (P4-straight) and bent nonyl chains (P4-bend1 and bend2). UV−vis absorption spectra by timedependent density functional theory showed intense metal-toligand charge transfer to anchor bipyridine ligands (MLCT-anchoring) at 445−460 nm, which accurately reproduce experimental data. The largest light-harvesting efficiency of the MLCT-anchoring state was observed in the P4-bend1 conformer, which has the lowest P4 energy. This may relate to greater electron injection in the P4 and supports experimental results of dye-only systems (do-DSPEC). The calculated charge transfer rates agree well with the experimental trend. The largest rate was obtained for P2, which was attributed to the expansion of the highest-occupied molecular orbital toward the ancillary bipy ligands and also to the short distances between dyes on the TiO 2 surface. These results also support experimental results for P2, which was the best compound for lateral hole-hopping in a sacrificial agent-containing system (sa-DSPEC).
The relativistic coupled-cluster (RCC) theory has been applied recently to a number of heavy mole... more The relativistic coupled-cluster (RCC) theory has been applied recently to a number of heavy molecules to determine their properties very accurately. Since it demands large computational resources, the method is often approximated to single and double excitations (RCCSD method). The effective electric fields ( E e f f ) and molecular permanent electric dipole moments (PDMs) of SrF, BaF, and mercury monohalides (HgX with X = F, Cl, Br, and I) molecules are of immense interest for probing fundamental physics. In our earlier calculations of E e f f and PDMs for the above molecules, we neglected the non-linear terms in the property evaluation expression of the RCCSD method. In this work, we demonstrate the roles of these terms in determining the above quantities and their computational time scalability with the number of processors of a computer. We also compare our results with previous calculations that employed variants of RCC theory, as well as other many-body methods and available ...
The dye-sensitized photoelectrochemical cells (DSPECs) incorporating a family of ruthenium comple... more The dye-sensitized photoelectrochemical cells (DSPECs) incorporating a family of ruthenium complexes [RuII(bipyP)(bipy)2] (P1), [RuII(bipyP)(dmb)2] (P2), [RuII(bipyP)(dtbb)2] (P3) and [RuII(bipyP)(dnb)2] (P4) where bipyP = 2,2'-bipyridine-4,4'-diphosphonic acid; bipy = 2,2'-bipyridine; dmb =...
Transition frequencies of cold molecules must be accurately evaluated to test the variance in the... more Transition frequencies of cold molecules must be accurately evaluated to test the variance in the protonto-electron mass ratio. Measuring the X 2 (v,N) = (0,0) → (1,0) transition frequency of optically trapped 174 Yb 6 Li molecules is a promising method for achieving this goal. The Stark shifts induced by trap and probe (for the Raman transition) lasers are eliminated by choosing appropriate frequencies (magic frequencies) during the construction of the optical lattice. In the far-off resonance region, the Stark shift is found to be less than 10 −16 even when the laser frequencies are detuned from the magic frequencies by ∼1 MHz.
The journal of physical chemistry. A, Jan 29, 2016
Methodologies beyond the Born-Oppenheimer (BO) approximation are nowadays important to explain hi... more Methodologies beyond the Born-Oppenheimer (BO) approximation are nowadays important to explain high precision spectroscopic measurements. Most previous evaluations of the BO correction are, however, focused on light-element molecules and based on a nonrelativistic Hamiltonian, so no information about the BO approximation (BOA) breakdown in heavy-element molecules is available. The present work is the first to investigate the BOA breakdown for the entire periodic table, by considering scalar relativistic effects in the Diagonal BO correction (DBOC). In closed shell atoms, the relativistic EDBOC scales as Z(1.25) and the nonrelativistic EDBOC scales as Z(1.17), where Z is the atomic number. Hence, we found that EDBOC becomes larger in heavy element atoms and molecules, and the relativistic EDBOC increases faster than nonrelativistic EDBOC. We have further investigated the DBOC effects on properties such as potential energy curves, spectroscopic parameters, and various energetic proper...
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Papers by Minori Abe