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1

Mössbauer Study of a Reduction Process in Iron Azaporphyrins

100%

Kaczmarzyk T., Jackowski T., Dziliński K., Kania L.

Acta Physica Polonica A

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2009

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vol. 115

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issue 3

656-659

EN

Electronic structure of the Fe(II)- and Fe(I)-complexes of mono- and diazaporphyrins studied by the Mössbauer spectroscopy is considered in this paper. It was found that in the presence of tetrahydrofuran molecules, the electron configuration of Fe(II) ions in the studied complexes corresponds to the intermediate spin state (S = 1) and the complexation of tetrahydrofuran solvent does not change this state. Interaction of tetrahydrofuran solvent with Fe(I)-azaporphyrins does not influence the electronic structure of Fe(I) ions coordinated to the porphyrin ligand, either. Electron configuration of Fe(I) ions in Fe(I)-octaethylporphyrins and Fe(I)-azaporphyrins is the same: (d_{xy})^{2}(d_{xz},d_{yz})^{4}(d_{z}^2)^{1}. The aza substitution is reflected in the values of the Mössbauer parameters. Increasing number of nitrogen atoms at meso positions causes the increase in the quadrupole splittings within the range 1.49-2.24 mm/s for the Fe(II) complexes and within the range 1.35-1.85 mm/s for the Fe(I)-porphyrins. Values of the isomer shifts are decreased from 0.51 to 41 mm/s for the same sequence of the Fe(II) complexes. For the Fe(I) reduced forms the isomer shifts are nearly constant and equal to about 0.37 mm/s. The Mössbauer results are discussed in association with EPR data for Fe(I)-porphyrins.

2

Conformation-Dependent Photophysics of Bifunctional Hydrogen Bond Donor/Acceptor Molecules

63%

Kijak M., Petkova I., Toczek M., Wiosna-Sałyga G., Zielińska A., Herbich J., Thummel R., Waluk J.

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EN

A series of heteroazaaromatic molecules possessing both a hydrogen bond donor and acceptor groups linked by a single bond was studied using electronic absorption and fluorescence techniques, combined with quantum-chemical calculations. Fluorescence lifetimes and quantum yields strongly depend on the solvent. Double exponential decays are observed in alcohols. This was interpreted in terms of alcohol-induced syn-anti rotamerization in the ground electronic state. The driving force for the conformational change is provided by two factors: (a) solvent polarity increase; (b) the formation of two separate hydrogen bonds in the anti species. In the syn structure, formation of cyclic hydrogen bonds leads to rapid depopulation of the lowest excited singlet state via two competing mechanisms: proton transfer and enhanced internal conversion. The experimental results are rationalized by calculations which include specific and nonspecific solvent effects.

3

Stable and Unstable Rovibrational States of a Molecule

51%

Konarski J.

Acta Physica Polonica A

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1999

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vol. 96

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issue 3-4

353-357

EN

Stability of motions for different potential functions describing vibrational motions of rotating molecule has been discussed. It was shown that an equilibrium position for nonrotating r_{0} and rotating r_{J} molecules for almost all the examined potentials is a node, but for the molecule described by the soft body model a critical value of rotation quantum number J_{c} occurs above which r_{0} is a saddle point, and the stable motion may occur only around r_{J}.

4

Investigation of the Spin-Orbit Perturbation of the 6¹Π State in KLi Molecule

51%

Jastrzebski W., Kowalczyk P.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

731-738

EN

Strong perturbation in the 6¹Π state of the ³⁹K⁷Li molecule is analysed. The perturbing state is identified as 3³∆ on the basis of experimental observations aided by comparison with recent theoretical calculations. Possibilities of accessing triplet states of KLi via the 6¹Π∼ 3³∆ perturbation are discussed.

5

Photoinduced Electron Transfer in Jet Cooled Molecular Complexes

51%

Piuzzi F., Uridat D., Dimicoli I., Mons M., Tramer A., LeBarbu K., Lahmani F., Zehnacker-Rentien A.

Acta Physica Polonica A

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1999

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vol. 95

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issue 1

121-135

EN

Exciplex and excimer formation have been probed in several jet cooled complexes using mass selective two-photon ionisation and fluorescence excitation spectroscopy as well as ground state depletion spectroscopy (hole burning): (i) In the anthracene-dimethyl-ortho-toluidine system, it has been found that the ionisation step takes place with a much higher efficiency from the charge transfer state responsible for the exciplex emission than from the locally excited state giving rise to the resonant fluorescence. (ii) The dimer, trimer, and higher clusters of anthracene all show only excimer emission. When compared to the dimer, the trimer exhibits a peculiar behaviour (structured fluorescence excitation and hole burning spectra, short lifetime and low ionisation efficiency) which has been related to a significant locally excited character of the initially prepared state of the species excited state. (iii) The influence of an intermolecular hydrogen bond on the electron transfer process has been studied in the 2,2,2-trifluoro-1-(9-anthryl)ethanol- dimethylaniline system. A threshold for exciplex formation higher than in the case of the anthracene-dimethylaniline complex is observed.

6

The C^1Σ^+ State of KLi Studied by Polarisation Labelling Spectroscopy Technique

51%

Grochola A., Kowalczyk P., Jastrzębski W., Crozet P., Ross A.

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EN

The polarisation labelling spectroscopy method is applied to study the C^1Σ^+← X^1 Σ^+ band system of the KLi molecule. Rotationally resolved polarisation spectra are observed in the spectral range of 17150-20350 cm^{-1}. A set of Dunham coefficients describes the C^1Σ^+ state to 95% of its potential well depth, and the potential curve is constructed by the Rydberg-Klein-Rees procedure. The molecular parameters deduced from this work are compared with theoretical calculations.

7

High-Pressure Study of Ion-Molecule Reactions in the Mixture of Carbon Tetrafluoride and Argon

51%

Bederski K.

Acta Physica Polonica A

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2013

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vol. 123

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issue 5

896-898

EN

Charge-exchange ion-molecule reactions of Ar^+ ions with CF_4 have been studied in the pressure range 1.33-39.99 Pa. A quadrupole mass spectrometer with a high-pressure ion source has been used for measuring gaseous ion-molecule reactions in the mixture of 1% CF_4 and 99% Ar. The fractional abundance I_i/∑ I_i of the observed CF_3^+, CF_2^+ and argon ions has been determined as a function of the gas mixture pressure (at the values of the repeller electrode potentials V_{R} ranging from 2 to 10 V).

8

Study of Adsorption Properties on Lithium Doped Activated Carbon Materials

51%

Łoś S., Duclaux L., Letellier M., Azaïs P.

Acta Physica Polonica A

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2005

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vol. 108

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issue 2

371-377

EN

A volumetric method was applied to study an adsorption coefficient of hydrogen molecules in a gas phase on super activated carbon surface. The investigations were focused on getting the best possible materials for the energy storage. Several treatments on raw samples were used to improve adsorption properties. The biggest capacities were obtained after high temperature treatment at reduced atmosphere. The adsorption coefficient at 77 K and 2 MPa amounts to 3.158 wt%. The charge transfer between lithium and carbon surface groups via the doping reaction enhanced the energy of adsorption. It was also found that there is a gradual decrease in the adsorbed amount of H_2 molecules due to occupation active sites by lithium ions.

9

Towards relativistic ECP / DFT description of chemical bonding in E112 compounds: spin-orbit and correlation effects in E112X versus HgX (X=H, Au)

32%

Zaitsevskii A., Rykova E., Mosyagin N., Titov A.

Open Physics

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2006

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vol. 4

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issue 4

448-460

EN

The relativistic effective core potential (RECP) approach combined with the spin-orbit DFT electron correlation treatment was applied to the study of the bonding of eka-mercury (E112) and mercury with hydrogen and gold atoms. Highly accurate small-core shape-consistent RECPs derived from Hartree-Fock-Dirac-Breit atomic calculations with Fermi nuclear model were employed. The accuracy of the DFT correlation treatment was checked by comparing the results in the scalar-relativistic (spin-orbit-free) limit with those of high level scalar-relativistic correlation calculations within the same RECP model. E112H was predicted to be slightly more stable than its lighter homologue (HgH). The E112-Au bond energy is expected to be ca. 25–30 % weaker than that of Hg-Au. The role of correlations and magnetic (spin-dependent) interactions in E112-X and Hg-X (X=H, Au) bonding is discussed. The present computational procedure can be readily applied to much larger systems and seems to be a promising tool for simulating E112 adsorption on metal surfaces.

Refine search results

Mössbauer Study of a Reduction Process in Iron Azaporphyrins

Conformation-Dependent Photophysics of Bifunctional Hydrogen Bond Donor/Acceptor Molecules

Stable and Unstable Rovibrational States of a Molecule

Investigation of the Spin-Orbit Perturbation of the 6¹Π State in KLi Molecule

Photoinduced Electron Transfer in Jet Cooled Molecular Complexes

The C^1Σ^+ State of KLi Studied by Polarisation Labelling Spectroscopy Technique

High-Pressure Study of Ion-Molecule Reactions in the Mixture of Carbon Tetrafluoride and Argon

Study of Adsorption Properties on Lithium Doped Activated Carbon Materials

Towards relativistic ECP / DFT description of chemical bonding in E112 compounds: spin-orbit and correlation effects in E112X versus HgX (X=H, Au)