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1

Normal Mode Analysis of Vibrations of Jet-Cooled Acridine Dimer

100%

Deperasińska I., Prochorow J.

Acta Physica Polonica A

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2000

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vol. 97

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issue 2

285-294

EN

The analysis of normal modes of vibrations was performed for acridine dimer, which has been recently observed and identified by laser-induced emission spectroscopy under conditions of jet-cooling in a supersonic helium expansion. The frequencies and the forms of normal vibrations, computed with the use of the semi-empirical PM3 method are classifying all vibrations of acridine dimer into two distinct categories of inter- and intramolecular vibrations. There are six low-frequency intermolecular normal vibrations which are characterizing relative movements of two acridine moieties in the dimer and at least two of them have vibrational frequencies which are close to the frequencies of vibronic bands observed in the fluorescence excitation spectrum of the dimer. The intramolecular normal vibrations of the dimer very strictly correspond to the normal vibrations of acridine molecule (with a minor modification of the vibrational frequencies due to the splitting in the dimer). Furthermore, the intramolecular vibrations of acridine dimer, as well as the vibrations of acridine molecule are in good agreement with available experimental data (either IR and Raman spectra of acridine or fluorescence excitation spectrum of acridine dimer in supersonic jet). The results of the present analysis are very clearly supporting the previous conclusions concerning the ground-state equilibrium structure of acridine dimer formed under jet-cooling conditions.

2

Theoretical Investigation of Electronic Structure and Vibrational Spectra of Conformers of Trinitrotoluene and Trinitrophenol

63%

Kleiza V., Bekešienė S.

Acta Physica Polonica A

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2011

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vol. 119

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issue 2

189-192

EN

The precise knowledge of vibrational spectra would allow detecting small amounts of these materials by means of spectroscopic methods. The results of the investigation of the vibrational spectra of trinitrotoluene and 2,4,6-trinitrophenol molecules were published in our previous paper, where we investigated the normal state of the molecules. In this paper we present the investigation results of the trinitrotoluene and trinitrophenol molecules conformer's with C_1 and Cs symmetry. We analyzed the potential surfaces and vibration spectra by means of ab initio quantum chemical calculations using basis of Gaussian functions and GAMESS package. Calculations were performed at the Hartree-Fock level and with account of the electron correlation. Personal computers clusters necessary for such investigations were made and SCore parallel environment was used.

3

Natural Bond Orbital (NBO) Population Analysis of 1-Azanapthalene-8-ol

51%

Gangadharan R., Sampath Krishnan S.

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vol. 125

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issue 1

18-22

EN

The molecular structure of 1-azanapthalene-8-ol was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian program. The results from natural bond orbital analysis have been analyzed in terms of the hybridization of atoms and the electronic structure of the title molecule. The stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital analysis. The electron density based local reactivity descriptors such as the Fukui functions were calculated. The dipole moment (μ) and polarizability (α), anisotropy polarizability (Δ α) and first order hyperpolarizability (β_{tot}) of the molecule have been reported.

4

Fluorescence Spectra of 7,8-Benzoquinoline Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

51%

Deperasińska I., Prochorow J., Stepanenko Y.

Acta Physica Polonica A

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2004

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vol. 106

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issue 4

535-545

EN

The optimized equilibrium geometry of 7,8-benzoquinoline molecule in its first excited, S_1, singlet state was computed with the use of ab initio RCIS/6-31G(d) method. It was found that the electronic transition to the first excited state in 7,8-benzoquinoline is not confined to the neighborhood of nitrogen atom, but is delocalized over entire aromatic rings system, much alike in the molecule of phenanthrene. With the optimized geometry of the ground and excited state of the molecule, the frequencies of the vibrational fundamental modes were computed, together with their displacement parameters (geometry changes of vibrations between the excited and the ground state). These frequencies are in good agreement with vibrational frequencies present in the fluorescence spectrum of 7,8-benzoquinoline observed recently under jet-cooling conditions in supersonic beam expansion. In comparison to the fluorescence spectrum of phenanthrene, the calculated, as well as experimental fluorescence spectra of 7,8-benzoquinoline contain much more vibrational features, and this increased vibronic activity is related to the symmetry break caused by the introduction of N-heteroatom into the aromatic ring system of phenanthrene.

5

Structure and Vibrational Studies of ±1-(1H-Benzoimidazol-2-YL) Ethanol, Using DFT Method

51%

Oturak H., Kaya Kinaytürk N., Şahın G.

Acta Physica Polonica A

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2015

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vol. 128

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issue 2B

B-417-B-421

EN

In this study, conformational analysis and quantum chemical calculations of ±1-(1H-Benzoimidazol-2-YL) Ethanol were carried out. The geometric structure, infrared intensities, UV-VIS spectrum, HOMO-LUMO energies, ^1H and ^{13}C nuclear magnetic resonance (NMR) chemical shifts were calculated by using the density functional method (DFT/B3LYP) with 6-311++G(d,p) basis set. The vibrational studies were interpreted in terms of potential energy distribution (PED). Finally, calculated values were compared with the experimental ones.

6

Comparative Study of Si-2p Core-Excitation Spectra of SiX_{4} Molecules (with X = H, D, F, Cl, Br)

51%

Püttner R., Domke M., Kaindl G.

Acta Physica Polonica A

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1997

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vol. 91

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issue 5

865-870

EN

Highly-resolved photoabsorption spectra of SiX_{4} molecules (with X = H, D, F, Cl, Br), recorded by photoionization in the region of the Si-2p absorption thresholds, are presented. Vibrational fine structure could be resolved in all cases, allowing a derivation of vibrational energies and intra-molecular distances of the core-excited molecules from Franck-Condon fits. In case of the heavier ligand atoms, spectral features arising from thermally-excited vibrational states of the electronic ground state were observed. The results obtained for the various ligand atoms are compared with each other and are discussed in the context of the equivalent-cores approximation.

7

Fluorescence Spectra of Phenanthridine Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

51%

Deperasińska I., Prochorow J., Stepanenko Y.

Acta Physica Polonica A

|

2005

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vol. 108

|

issue 6

1005-1019

EN

Following the analysis of laser induced fluorescence spectrum of 7,8-benzoquinoline molecule, observed under conditions of isolation in the supersonic jet expansion, the ab initio analysis of laser induced fluorescence spectrum of phenanthridine, observed under the same experimental conditions, was performed. This analysis included: optimization of equilibrium geometry of phenanthridine in its first excited S_1 singlet state and computations of the frequencies of vibrational fundamental modes together with their geometry changes between the excited and the ground state. Comparison of the results of calculations with experimental data revealed their good agreement and an increase in the vibrational activity in the fluorescence spectrum in comparison to fluorescence spectrum of phenanthrene molecule (which is a parent aromatic hydrocarbon of phenanthridine and of 7,8-benzoquinoline). Such an increase in vibrational activity in the fluorescence spectrum was earlier observed also for 7,8-benzoquinoline molecule. Present analysis shows that this effect is due to molecular symmetry reduction caused by the substitution of nitrogen atom into the aromatic rings system of phenanthrene, as well as to the changes of equilibrium structure between the ground and excited states.

8

Proton Transfer in Strong Hydrogen Bonds Revealed by Infrared Spectra - Correlations between Structure and Spectra for the BrH : NH_3 Complex

45%

Szczepaniak K., Person W.

Acta Physica Polonica A

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2007

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vol. 112

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issue S

S-19-S-38

EN

Our scope is to achieve an understanding of the relation between the infrared spectrum and structure of a strong hydrogen-bonded complex, BrH : NH$_3$, and how and why this relationship is affected by the environment surrounding the complex. A series of DFT/B3LYP/6-31G(d,p) calculations was carried out for this system to obtain its structure and spectrum in different dielectric fields characterized by their relative permittivities. Changes in structure and spectrum (both frequencies and intensities) as the relative permittivity changes are explored. Calculations of spectra are made first under the harmonic approximation. In the next step the effect of anharmonicity was estimated for several different dielectric fields. The calculated anharmonic spectrum (for ε_r = 1.6) is compared with the experimentally observed infrared spectrum of the complex isolated in an Ar matrix at 10 K, obtained in our laboratory. The calculated frequencies and relative intensities for all normal modes agree with the corresponding experimental data surprisingly well. The potential usefulness of structure-spectra correlations is explored.

9

Experimental and Quantum Chemical Calculations of 2-Amino-4,5,6,7-Tetrahydrobenzo[b]Thiophene-3-Carbonitrile

38%

Oturak H., Kaya Kinaytürk N., Topuz M., Kutlu N., Kaynaker E., Talıp P., Sert Y.

Acta Physica Polonica A

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2017

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vol. 132

|

issue 3

1192-1199

EN

Vibrational frequencies of 2-Amino-4,5,6,7-Tetrahydrobenzo[b]Thiophene-3-Carbonitrile were calculated using density functional (DFT/B3YLP) method with 6-311++G(d,p) basis set by Gaussian 09. The assignments of the vibrational frequencies have been done by potential energy distribution analysis, using VEDA 4 software. The density functional theory and time dependent density functional theory methods have been used to study the electronic properties of 2-Amino-4,5,6,7-Tetrahydrobenzo[b]Thiophene-3-Carbonitrile. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital method. All computed spectroscopic properties were compared with experimental ones. The simulated spectra of the molecule show excellent agreement with the experimental spectra.

10

Spectral Investigations of Fullerene-Porphyrin Complexes

32%

Barszcz B., Bogucki A., Laskowska B., Ion R., Graja A.

Acta Physica Polonica A

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2007

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vol. 112

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issue S

S-143-S-152

EN

Spectral investigations of someμ-oxo-dimer complexes of trivalent metals (Mn, Fe) with two different ligands: tetraphenylporphyrin and tetranaphthylporphyrin (TNP), and fullerene (C_{60} and C_{70}) complexes withμ-oxobis[5,10,15,20-tetraarylporphyrinatometal (III)] (TXP-M)_2O dimer, where M = Fe, Mn and X = phenyl or naphthyl, are presented. Discussion of the main electronic and vibrational bands observed in the UV-Vis-IR and Raman spectra of both classes of fullerene-porphyrin systems is given. Experimental data are completed with the quantum chemical calculations of MnTNP^+ component.

Refine search results

Normal Mode Analysis of Vibrations of Jet-Cooled Acridine Dimer

Theoretical Investigation of Electronic Structure and Vibrational Spectra of Conformers of Trinitrotoluene and Trinitrophenol

Natural Bond Orbital (NBO) Population Analysis of 1-Azanapthalene-8-ol

Fluorescence Spectra of 7,8-Benzoquinoline Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

Structure and Vibrational Studies of ±1-(1H-Benzoimidazol-2-YL) Ethanol, Using DFT Method

Comparative Study of Si-2p Core-Excitation Spectra of SiX_{4} Molecules (with X = H, D, F, Cl, Br)

Fluorescence Spectra of Phenanthridine Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

Proton Transfer in Strong Hydrogen Bonds Revealed by Infrared Spectra - Correlations between Structure and Spectra for the BrH : NH_3 Complex

Experimental and Quantum Chemical Calculations of 2-Amino-4,5,6,7-Tetrahydrobenzo[b]Thiophene-3-Carbonitrile

Spectral Investigations of Fullerene-Porphyrin Complexes