Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 8

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  82.30.Fi
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Influence of Repeller Potential on Ion-Molecule Reactions in H_2S and CH_4 Mixtures

100%
Wójcik L., Markowski A.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 1
13-15
EN
Ion-molecule reactions initiated by electron impact in the hydrogen sulfide-methane mixtures have been studied by means of quadrupole mass spectrometer with a high-pressure ion source. The total gas pressure of investigated mixtures was changed from 0.7 to 33.3 Pa. Influence of repeller potential on ion-molecule reactions have been studied. The repeller potential was changed in the range 2-12 V. Measurements were performed for different concentrations of methane and hydrogen sulfide in the mixture (from 10% H_2S + 90% CH_4 to 90% H_2S + 10% CH_4 with 10% increment). The major ion-molecule reactions have been identified. The primary ions C^{+}, CH^{+}, CH_2^{+}, CH_3^{+}, CH_4^{+}, S^{+}, HS^{+}, H_2S^{+} produced in gas by the electrons with the energy of 300 eV and secondary CH_5^{+}, C_2H_5^{+}, H_3S^{+}, H_2^{34}S^{+}, H_3^{34}S^{+}, CHS^{+}, CH_3S^{+}, S_2^{+}, HS_2^{+}, H_2S_2^{+} and H_3S_2^{+} from the ion-molecule reactions were observed. Relative intensities for primary and secondary ions are presented as a function of potential of repeller electrode and concentration of methane in the mixture.
2
Publication available in full text mode
Content available

Photoinduced Charge-Transfer Reactions of Tricyanoethylene with Aromatic Hydrocarbon Electron Donors. II. Semiempirical Studies of Naphthalene-Tricyanoethylene Exciplex

100%
Deperasińska I., Prochorow J.
Acta Physica Polonica A
|
2002
|
vol. 102
|
issue 6
811-826
EN
In this work we present the results of semiempirical AM1 calculations of the energy of electron-donor-acceptor system of naphthalene-tricyanoethylene complex in the ground and excited state with full optimization of the complex geometry. It was found that a ground state of the complex under consideration is stabilized almost exclusively by the electrostatic and Van der Waals interactions (presumably without charge-transfer resonance interaction). Its optimized equilibrium configuration has almost perpendicular head-to-face orientation of component molecules while in an excited state it is practically a charge-transfer electronic configuration with almost sandwich-like arrangement of both molecules. The energies of vertical electronic transitions between relevant ground and excited states and other spectroscopic parameters for these transitions were calculated with the use of ZINDO/S method and were compared with results of recent experimental observations of naphthalene-tricyanoethylene exciplex. This comparison led to a satisfactory explanation of the spectral properties and to a deeper insight into the kinetic parameters of the electron-donor-acceptor system under study.
3
Content available remote

Single Ionization of He by High-Energy Proton and Antiproton. A QED Approach

100%
Bhattacharyya S., Pathak K.
Acta Physica Polonica A
|
2000
|
vol. 98
|
issue 4
335-344
EN
We have investigated single ionization of He by fast proton and antiproton using a QED approach. A field theoretical calculation gives the total cross-section of He in single ionization, from which it is seen that the projectile p^{+} or p^{-} gives almost the same values of cross-section. We have also compared our results with other theoretical and experimental results available in this context yet. Behaviour of the cross-section at a lower spectrum of projectile energy is discussed.
4
Content available remote

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

80%
Bederski K.
Acta Physica Polonica A
|
2013
|
vol. 123
|
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).
5
Content available remote

Environment of Air-Ions in Healing Chambers in the "Wieliczka" Salt Mine

80%
Wiszniewski A.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 6
1661-1665
EN
The present paper is an attempt to determine the parameters of air-ions in salt mines. The investigations were aimed at determination of the degree of ionization of air in places where cosmic ray particles do not arrive at. Specifically, measurements were performed in healing chambers in salt mines where establishment of standards in the healing process should be considered as the necessity. Preliminary investigations were carried out in three salt mines using the Gerdien ion counter, with sensitivity approximately of 20 ions/cm^{3}. The studies have shown that concentrations of small air-ion are in the range of 1200-4700 ions/cm^{3} and remain persistently in adits and medicinal chambers of this mine. It means that the air in the "Wieliczka" Salt Mine is several times more saturated with air-ions as compared to the neutral atmosphere background. According to the existing standards, this ionization level is not only deemed acceptable but also optimal for humans. Because results of unsystematic measurements of ion concentrations performed in different Polish salt mines are quite similar, it is assumed that the results presented in this paper are of universal character, and that comparable ionization level in the all mines would be expected. Due to this fact, it was decided that only one of them "Wieliczka" Salt Mine (Poland) can be selected for further detailed research.
6
Publication available in full text mode
Content available

Photoinduced Charge-Transfer Reactions of Tricyanoethlene with Aromatic Hydrocarbon Electron Donors. I. Emission Studies of Naphthalene-Tricyanoethylene Exciplex

80%
Dresner J., Kwapisz K., Deperasińska I., Prochorow J., Bruni P., Giardina A., Tosi G.
Acta Physica Polonica A
|
2002
|
vol. 102
|
issue 3
443-468
EN
The fluorescence quenching of a series of aromatic hydrocarbon electron donors by an electron acceptor tricyanoethylene has been observed. The quenching mechanism is consistent with the charge-transfer (or electron-transfer) mechanism, as indicated by the appearance of a new, broad, and structureless exciplex emission band. Detailed, steady-state, and time-resolved emission studies of the kinetics and thermodynamics of exciplex formation and relaxation have been performed for naphthalene-tricyanoethylene system. It was found that the kinetics of monomer-exciplex equilibrium for this system, in a non-polar solvent (n-hexane), can be described in terms of a simple two-state photokinetic scheme. Within such a scheme, under conditions of the present experiment, napthalene-tricyanoethylene system approaches the limits under which exciplex formation is very effective - it becomes exclusively diffusion-controlled and at the same time a competitive process of thermal dissociation of exciplex ceases to operate. This leads to a very rarely observed reversal of physical meaning of the decay parameters which are describing the rise and the decay of exciplex fluorescence.
7
Content available remote

Photoinduced Charge Separation Processes in Supramolecular Triad Systems

80%
Pirowska K., Najbar J.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 4
637-654
EN
The nonadiabatic electron transfers in donor-acceptor-acceptor systems are investigated using three potential energy surfaces and two reaction coordinates via the stochastic Liouville equation to describe time evolution of the three excited electronic states: (1) D*-A-A, (2) D^{+}-A^{-}-A and (3) D^{+}-A-A^{-}. The electronic dephasing processes are taken into account phenomenologically in terms of dephasing constants. The couplings between surfaces are effective along the intersections of pairs of surfaces in the two-dimensional coordinate space. Special situations occur in the reaction coordinate space when three surfaces are nearly degenerate. The interplay between the sequential electron transfer processes and the superexchange process is analysed for different: reorganization energies, electronic coupling, free energies for the electron transfer, dephasing rates, and temperature. The time dependent contribution of the superexchange process to the charge separation in the triad system is analysed using the time dependent rate functions. It is shown that in the nonadiabatic limit of electron transfer the influence of the electronic dephasing processes for low barrier reactions can be accounted for by appropriate changes in the reorganization energies. The present model is compared with the experimental results concerning the charge separation in the bacterial photosynthetic reaction centers.
8
Content available remote

Mass Spectrometric Study of Positive Ion-Molecule Reactions in the C_{3}H_{6} and Ar Mixtures Inside the High Pressure Ion Source

80%
Markowski A., Szot E., Wójcik L.
Acta Physica Polonica A
|
2013
|
vol. 123
|
issue 5
911-915
EN
Ion-molecule reactions have been measured for the propene-argon mixtures of different compositions using a quadrupole mass spectrometer with a high-pressure ion source. The concentration of propane in these mixtures ranged from 10% to 90% (at 10% increment). The following primary and secondary ions: CH_{5}^{+} (m/q=17), C_{2}H_{2}^{+} (m/q=26), C_{2}H_{3}^{+} (m/q=27), C_{2}H_{4}^{+} (m/q=28), C_{2}H_{5}^{+} (m/q=29), C_{3}H_{3}^{+}/^{39}Ar^{+} (m/q=39), C_{3}H_{4}^{+}/^{40}Ar^{+} (m/q=40), C_{3}H_{5}^{+} (m/q=41), C_{3}H_{6}^{+}/^{42}Ar^{+} (m/q=42), C_{3}H_{7}^{+} (m/q=43), C_{3}H_{8}^{+} (m/q=44), C_{4}H_{5}^{+} (m/q=53), C_{4}H_{6}^{+} (m/q=54), C_{4}H_{7}^{+} (m/q=55), C_{4}H_{8}^{+} (m/q=56), C_{4}H_{9}^{+} (m/q=57), C_{5}H_{5}^{+} (m/q=65), C_{5}H_{6}^{+} (m/q=66), C_{5}H_{7}^{+} (m/q=67), C_{5}H_{8}^{+} (m/q=68), C_{5}H_{9}^{+} (m/q=69), C_{5}H_{10}^{+} (m/q=70) were observed. Relative ion current intensities for primary and secondary ions are presented as a function of both total mixtures pressure and concentration of propene in the mixture. Primary ions were produced by electrons with the energy of 300 eV. The potential of repeller electrode V_{R} inside the ion source collision chamber was fixed at 5 V for all measurements. The total mixture pressure was changed from 0.7 to 26.6 Pa. Schemes of ion-molecule reactions were proposed.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.