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1

Elastic Positron Scattering from Krypton and Xenon in the Relativistic Polarized Orbital Approximation

100%

Szmytkowski R.

Acta Physica Polonica A

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1994

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vol. 86

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issue 3

309-314

EN

We present results of ab initio relativistic calculations on the elastic positron scattering from Kr and Ye atoms in the energy region below 10 eV. The approach employed was the relativistic polarized orbital approximation in which we tried to keep correctly orders of various contributions to positron-atom interaction potentials. In view of the serious disagreement between the present results and experimental data we conclude that the polarized orbital approximation even in its relativistic version is not able to provide reliable values of positron scattering cross-sections.

2

Elastic Positron Scattering from Zinc and Cadmium in the Relativistic Polarized Orbital Approximation

100%

Szmytkowski R.

Acta Physica Polonica A

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1993

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vol. 84

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issue 6

1035-1040

EN

Results of relativistic calculations on the elastic positron scattering from zinc and cadmium atoms are presented in the low-energy region. The ab initio calculated polarization potentials applied in these calculations were obtained by solving the coupled Dirac-Hartree-Fock equations. It is shown that the indirect relativistic effects play an important role in the description of the scattering process. Particularly, relativity has a great influence on values of scattering lengths.

3

Production of Similar Fragments from the Glycine, Alanine, and Methionine Amino Acid Molecules under Low-Energy Electron Impact

100%

Romanova L., Tamuliene J., Vukstich V., Snegurskaya T., Papp A., Snegursky A.

Acta Physica Polonica A

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2015

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vol. 128

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issue 1

15-24

EN

Production of the ionic fragments of the same chemical composition due to a low-energy electron impact on the glycine, alanine, and methionine amino acid molecules has been studied both experimentally and theoretically. The mass-spectrometric technique was applied to detect the above ionic fragments within the 1-720 a.m.u. mass range with the ± 0.25 a.m.u. resolution, while the density functional theory based theoretical approach allowed the relevant species to be identified and the mechanisms of their production to be clarified. A special attention has been paid to analysis of the geometrical structures of the molecules under study as well to finding the appearance potentials of their fragments with the accuracy of ±0.1 eV.

4

Observation of "Diffusion Modes" in Measurement of the Diffusion Coefficient of Cesium in Noble Gases

100%

Rudecki P.

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EN

A set of experiments investigating diffusion of alkali atoms in the noble gases is reported. A cesium gradient in the cell was induced by electrodeless pulse discharge. In the transient signal of absorption, corresponding to the ^2S_{1/2}-n^2P_J transitions, five diffusion modes were observed. The diffusion coefficient D of cesium in helium and argon has been measured in a spherical cell filled with a buffer gas of 2.5 to 30 hPa and for temperatures in the range from 275 K to 400 K.

5

Luminescent Probe for Highly Energetic Collisions in Mixtures of Complex Molecules with Acceptors of Vibrational and Triplet Energy

80%

Zalesskaya G., Yakovlev D., Sambor E., Baranovsky D.

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vol. 95

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issue 6

897-910

EN

Pressure dependences of intensities and decay rates of time-resolved luminescence of acetophenone, benzophenone, anthraquinone were used to obtain the efficiencies of vibrational and triplet-triplet energy transfer. It was shown that vibrational relaxation of the chosen molecules can be interpreted in terms of two consecutive processes: rapid collisional relaxation of molecules from initially prepared states to a vibrational distribution at T_{vib} by vibration-vibration process and relaxation of this vibrational distribution to the thermal one (vibration-translation process). At relatively small internal energy < 10000 cm^{-1}, the collisional efficiencies of the vibration-vibration process in mixtures with polyatomic bath gases had values typical of processes with a supercollision contribution. Molecules relaxed from the upper vibrational level to the vibrational distribution after several collisions (2-3). The average energies transferred per collision are well correlated with predictions of the simple ergodic theory of collisional energy transfer. The majority of the collisions took part only in vibration-translation energy transfer of relatively small energies. The efficiencies of triplet-triplet energy transfer were analyzed for acetophenone, benzophenone and anthraquinone as donors and biacetyl-acceptor in a gas phase when energy of about 20000 cm^{-1} was transferred. It permitted us to elucidate the common features of highly energetic collisions. It was shown that the efficiencies are much lower than the gas kinetic ones and depended on the vibrational energy and temperature. It was discussed how to enhance triplet-triplet efficiencies due to vibrational excitation of a donor molecule.

6

Measurements of the Diffusion and Reflection Coefficients of Cd(^1S_0) in Noble Gases

80%

Rudecki P., Domysławska J.

Acta Physica Polonica A

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2003

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vol. 104

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issue 6

589-600

EN

A new method of simultaneous determining of the diffusion coefficient and the reflection coefficient of atoms from the reservoir walls is presented. The diffusion coefficient of cadmium atoms in the ground state in buffer noble gas atoms such as Ne, Ar, Kr, and Xe and reflection coefficient of Cd atoms from the quartz cell wall in the temperature range 350-550 K were determined. Experimental values of diffusion coefficient are compared with theoretical ones calculated from available potentials.

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Elastic Positron Scattering from Krypton and Xenon in the Relativistic Polarized Orbital Approximation

Elastic Positron Scattering from Zinc and Cadmium in the Relativistic Polarized Orbital Approximation

Production of Similar Fragments from the Glycine, Alanine, and Methionine Amino Acid Molecules under Low-Energy Electron Impact

Observation of "Diffusion Modes" in Measurement of the Diffusion Coefficient of Cesium in Noble Gases

Luminescent Probe for Highly Energetic Collisions in Mixtures of Complex Molecules with Acceptors of Vibrational and Triplet Energy

Measurements of the Diffusion and Reflection Coefficients of Cd(^1S_0) in Noble Gases