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Tytuł:
Adsorption Properties of the Cu(115) Surface: Basic Interfaces
Autorzy:
Godowski, P.
Groso, A.
Hoffmann, S.
Onsgaard, J.
Powiązania:
https://bibliotekanauki.pl/articles/1537740.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.43.Fg
68.55.Ac
61.14.Hg
79.60.Dp
Opis:
The interfaces: K/Cu(115) and CO/Cu(115) have been characterized using surface sensitive techniques, including low energy electron diffraction and photoelectron spectroscopy. K adatoms show tendency to occupy the sites close to the step edges. At low temperature (near 125 K), after completion of two layers, potassium grows in 3D islands (the Stranski-Krastanov mode). At higher temperature, e.g. at room temperature, potassium introduces reconstruction of the substrate even at low coverages. Calibration of the alkali coverage, up to completion of the first layer, using the work function changes curve has been confirmed as a very convenient and precise procedure. The adsorbed state of CO at 130 K has been identified by registration of core levels obtained by the use synchrotron radiation photoelectron spectroscopy. The characteristics of the main 1s and satellite peaks have been analyzed in context of substrate geometry and compared with the ones of other copper planes. There are no indications of dissociative adsorption of CO, only residual carbon and oxygen were found after adsorbate desorption around 220 K. CO molecules show a strong tendency to "on top" adsorption in sites far from the step edges of the Cu(115) surface.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 928-935
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications of the Transport Integrals in Solid-State Physics and in Electron Spin Relaxation
Autorzy:
Radczyk, T.
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036991.pdf
Data publikacji:
2003-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
Transport integrals I$\text{}_{n}$(Θ$\text{}_{D}$/T) are reviewed with their applications in solid-state physics, molecular dynamics, and electron spin-lattice relaxation. Analytical approximations of I$\text{}_{n}$ for n=2-8 are proposed as applicable for computer fitting procedures in the range of the variable x=Θ$\text{}_{D}$/T from 0.1 to 40. The results are applied for description of the spin-lattice relaxation data collected for Cu$\text{}^{2+}$ ions in triglycine sulphate and are compared with relaxation data for Cu$\text{}^{2+}$ and Mn$\text{}^{2+}$ in (NH$\text{}_{4}$)$\text{}_{2}$Mg(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O.
Źródło:
Acta Physica Polonica A; 2003, 104, 5; 469-477
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania nad częściowym rozkładem fosforytu (metodą PAPR) z zastosowaniem kwasu siarkowego i fosforowego
Investigation on the phosphate rock dissolution process by partial acidulation (PAPR method) using sulfuric and phosphoric acid
Autorzy:
Hoffmann, K.
Skut, J.
Rybarski, S.
Hoffmann, J.
Powiązania:
https://bibliotekanauki.pl/articles/126579.pdf
Data publikacji:
2011
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
fosforyty częściowo rozłożone (PAPR)
kwasy mineralne
nawozy fosforowe
fosforany przyswajalne
partially acidulated phosphate rocks (PAPR)
mineral acids
phosphate fertilizers
available Phosphorus
Opis:
Przedstawiono wyniki badań nad wpływem różnych czynników, przy częściowym rozkładzie surowca fosforowego, na zawartość fosforu w produkcie nawozowym. Uwzględniono wpływ rodzaju, stężenia i ilości kwasu mineralnego oraz uziarnienia surowca na zawartość poszczególnych form fosforanów oznaczonych zgodnie z Rozporządzeniem (WE) nr 2003/2003 Parlamentu Europejskiego i Rady z 13.10.2003 r. w sprawie nawozów dotyczącym metod badań zawartości fosforanów w nawozach sztucznych.
The results of few factors on the each form of phosphates content in the PAPR-type fertilizer preparations were presented. Type of mineral acid, its concentration, amount and fineness were taken into account. Investigation was carried out with the recommendations enclosed in Regulation (EC) No. 2003/2003 of the European Parliament and the Council on 13.10.2003 related to fertilizers, test methods for the phosphate content evaluation in fertilizers.
Źródło:
Proceedings of ECOpole; 2011, 5, 2; 531-536
1898-617X
2084-4557
Pojawia się w:
Proceedings of ECOpole
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Binding of the Trace Elements: Cu(II) and Fe(III) to the Native and Modified Nutritive Potato Starches Studied by EPR
Autorzy:
Śmigielska, H.
Lewandowicz, G.
Goslar, J.
Hoffmann, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/2043599.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
87.15.-v
Opis:
The Cu(II) and Fe(III) ions have been adsorbed by four potato starches of different degrees of oxidation (different numbers of COOH groups replacing host CH$\text{}_{2}$OH groups): native (no oxidized), white (pudding) with oxidation degree of 0.04%, gelating (0.1%), and LUBOX starch (0.5%). Concentration of the ions in starches was determined from atomic absorption and EPR spectrum intensity. For small concentration of the adsorbed ions (below 4 mg/g) nearly all ions are adsorbed from the solution. EPR shows that adsorbed copper(II) ions are chemically bonded to the starch molecules (preferably) at COOH sites and uniformly dispersed in the starch structure. The complexes are typical of octahedral or square-quadratic coordination with spin-Hamiltonian parameters g$\text{}_{ǁ}$=2.373, g$\text{}_{⊥}$= 2.080, A$\text{}_{ǁ}$=12.1 mT, A$\text{}_{⊥}$=1.0 mT. For higher concentrations the Cu(II) displays a tendency to clustering. Iron(III) ions are introduced into starch in a form of clusters mainly, even for the smallest concentration. The highest concentrations of both Cu(II) and Fe(III) were observed in LUBOX starch having the highest degree of oxidation.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 303-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Vibronic Dynamics of Cu(H$\text{}_{2}$O)$\text{}_{6}$ Complexes and Electron Spin Relaxation in Temperature Dependence of EPR Linewidth in Diamagnetic Tutton Salt Single Crystals
Autorzy:
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047171.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
EPR linewidth of Cu$\text{}^{2+}$ in the Tutton salt crystals weakly depends on temperature at low temperatures and then it rapidly grows above 60 K. We present detailed results of measurements and analysis for $\text{}^{63}$Cu$\text{}^{2+}$ in K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O, K$\text{}_{2}$ Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O, (NH$\text{}_{4}$)$\text{}_{2}$Mg(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O and Cs$\text{}_{2}$Zn (SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O in a temperature range of 4.2-300 K and compare them with already published electron spin-lattice relaxation data. The relaxation contributes weakly to the linewidth which is dominated by molecular dynamics and grows exponentially with temperature. To describe this we are discussing the influence of jumps between two sites of Cu$\text{}^{2+}$ complexes in a slow motion region where the sites are differently thermally populated. This case has not been considered so far. We have derived appropriate expressions describing the contribution of jumps to the linewidth which allows the determination of the jump rate and energy difference δ$\text{}_{A,B}$ between the two sites being two Jahn-Teller distorted configurations of the vibronic Cu(H$\text{}_{2}$O)$\text{}_{6}$ complexes. The jump rate 1/τ strongly depends on temperature and reaches 10$\text{}^{9}$ s$\text{}^{-1}$ at room temperature, whereas theδ$\text{}_{A,B}$ varies from 117 cm$\text{}^{-1}$ for K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O to 422 cm$\text{}^{-1}$ for Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O. The comparison with vibronic level splitting, which varies in the range of 67-102 cm$\text{}^{-1}$, indicates that the reorientation mechanism involves phonon induced tunnelling via excited vibronic levels. These reorientations do not contribute, however, to the spin-lattice relaxation which is governed by ordinary two-phonon relaxation processes in the whole temperature range. Thus, the reorientations and spin relaxation are two independent phenomena contributing to the total linewidth.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 807-816
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Spin Echo Envelope Modulation Analysis of SeO¯$\text{}_{3}$ Radical in (NH$\text{}_{4}$)$\text{}_{3}$H(SeO$\text{}_{4}$)$\text{}_{2}$ Single Crystal
Autorzy:
Tritt-Goc, J.
Goslar, J.
Hilczer, W.
Hoffmann, S.
Augustyniak, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/1929835.pdf
Data publikacji:
1993-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.Lz
76.30.Mi
Opis:
A detailed computer analysis of the electron spin echo envelope modulations of SeO$\text{}_{3}$ radical in a suitable orientation of (NH$\text{}_{4}$)$\text{}_{3}$H(SeO$\text{}_{4}$)$\text{}_{2}$ single crystal is presented. It was found that the modulations are due to a weak dipolar coupling with nitrogens and protons of the only two neighbouring NH$\text{}_{4}$ groups among the five NH$\text{}_{4}$ groups surrounding SeO¯$\text{}_{3}$ center. Isotropic dipolar coupling constant is 1.7 MHz for nitrogens and 0.9 MHz for protons. It was shown that thermal reorientations of NH$\text{}_{4}$ groups observed by NMR have a negligible effect on the electron spin echo envelope modulation pattern but can be responsible for the same value of a$\text{}^{H}$$\text{}_{iso}$ for all protons in a NH$\text{}_{4}$ group. A good fit obtained between experimental spectra and theoretical calculations assuming nondisturbed crystal geometry indicates a small damage of the crystal by X-rays during the radical center formation.
Źródło:
Acta Physica Polonica A; 1993, 84, 6; 1131-1141
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Spin Relaxation of Cu(II) Ions in ZnGeF$\text{}_{6}$·6H$\text{}_{2}$O Crystal with Strong Jahn-Teller Effect
Autorzy:
Idziak, S.
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2043479.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
Cu$\text{}^{2+}$ ions doped to ZnGeF$\text{}_{6}$·6H$\text{}_{2}$O substitute the host Zn$\text{}^{2+}$ ions and undergo a strong Jahn-Teller effect producing nearly axial elongation of the Cu(H$\text{}_{2}$O)$\text{}_{6}$ octahedra with equal population of the three possible deformations at low temperatures as shown by the EPR spectra. Reorientations between these distorted configurations are observed as a continuous shift of EPR lines leading to averaging of the g- and A-tensors. The full averaging is observed at the phase transition temperature 200 K. Electron spin relaxation was measured up to 45 K only, where the electron spin echo signal was detectable. Electron spin-lattice relaxation is governed by the Raman two-phonon process allowing to determine the Debye temperature asΘ$\text{}_{D}$=99 K. There is no contribution of the Jahn-Teller dynamics to the spin-lattice relaxation rate. Electron spin echo decay is strongly modulated by dipolar coupling to the $\text{}^{1}$H and $\text{}^{19}$F nuclei. The phase memory time is governed by instantaneous diffusion at helium temperatures and then by spin-lattice relaxation processes and excitation to the first vibronic level of energyΔ=151 cm$\text{}^{-1}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 177-185
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Spin-Lattice Relaxation in Polymers and Crystals Related to Disorder and Structure Defects
Autorzy:
Hoffmann, S. K.
Hilczer, W.
Radczyk, T.
Polus, I.
Powiązania:
https://bibliotekanauki.pl/articles/2035737.pdf
Data publikacji:
2003-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.41.+e
61.80.-x
76.30.-v
Opis:
Temperature dependences (4-300 K) of the electron spin-lattice relaxation have been determined by electron spin echo technique for free radicals in two polymeric systems: phenol-formaldehyde resin and polyhydrazodisulphide. The dependences are described in terms of dynamics specific for amorphous systems involving two-level tunnelling states at low temperatures, exchange-coupled clusters of paramagnetic centres and local oscillators. Some universal temperature behaviour of the spin-lattice relaxation of amorphous systems is suggested, with a strong increase in relaxation rate with temperature at low temperatures and much weaker increase above 50 K with characteristic linear temperature dependence in a broad temperature range and cosech(Δ/kT) -type behaviour. It is also shown that the amorphous-type behaviour appears in low temperatures relaxation studies of single crystals but it is due to a non-uniform distribution of doped paramagnetic ions. Such behaviour we have found in Tutton salt crystals doped with Cu$\text{}^{2+}$, as well as for free radical centres produced by ionising irradiation in (NH$\text{}_{4}$)$\text{}_{3}$H(SeO$\text{}_{4}$)$\text{}_{2}$ and Li(N$\text{}_{2}$H$\text{}_{5}$)SO$\text{}_{4}$ single crystals, where extended phonons are suppressed around radiation damage centres suggesting a local amorphisation of the crystal structure.zapisz i p
Źródło:
Acta Physica Polonica A; 2003, 103, 4; 373-385
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emisja lotnych związków fluoru z procesów wytwarzania fosforytów częściowo rozłożonych
Emission of volatile fluorine compounds from production processes of partially acidulated phosphate rocks
Autorzy:
Hoffmann, K.
Skut, J.
Rybarski, S.
Powiązania:
https://bibliotekanauki.pl/articles/125703.pdf
Data publikacji:
2014
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
nawozy fosforowe
fosforyty częściowo rozłożone
PAPR
lotne związki fluoru
phosphate fertilizers
partially acidulated phosphate rock
volatile fluorine compounds
Opis:
Celem niniejszej pracy była ocena emisji lotnych związków fluoru z produktów rozkładu fosforytów Maroko II (Afryka Północna) oraz ZIN (Izrael) techniką PAPR (Partially Acidulated Phosphate Rock). Z przeprowadzonych badań wynika, że stosowanie technologii PAPR jako alternatywy dla konwencjonalnych nawozów fosforowych, otrzymywanych metodą superfosfatową, powoduje zmniejszenie emisji zorganizowanej F–. Dla założonej zdolności produkcyjnej 800 Mg produktów nawozowych typu PAPR na dobę obniżenie wartości ηPAPR z 1,0 (SSP) do 0,3 powoduje redukcję F– średnio: 528,4→178,3 kg/dobę; podczas gdy obniżenie wartości ηPAPR z 1,0 (SSP) do 0,5 powoduje redukcję F– średnio: 528,4→170,2 kg/dobę. Niższa zawartość F–, prowadząca jednocześnie do ograniczenia ilości powstającej krzemionki, oprócz poprawy aspektów ochrony środowiska naturalnego, może pozwolić na zmniejszenie natężenia przepływu gazów odlotowych lub gęstości zraszania, co potencjalnie może prowadzić do obniżenia kosztów oczyszczania 1 m3 gazu.
The aim of this paper was to evaluate the emission of volatile fluorine compounds from the products of Morocco II (North Africa) and ZIN (Israel) phosphate rocks acidulation by PAPR technique. The study indicates that the use of PAPR technology as an alternative to conventional superphosphatic fertilizers reduces F– straight emission. For the assumed production capacity of 800 Mg of PAPR fertilizer products per day a decrease in ηPAPR value from 1.0 (SSP) to 0.3 causes a reduction in F– by average: 528.4 → 178.3 kg/day, while decrease in ηPAPR value from 1.0 (SSP) to 0.5 causes a reduction in F– by average: 528.4 → 170.2 kg/day. Despite improvement of environmental protection issues, the lower content of F–, which leads concurrently to reduce the amount of resulting silica, may allow also a reduction in off-gas flow intensity, or spraying density, which could potentially lead to decrease the cost of purification of 1 m3 of gas.
Źródło:
Proceedings of ECOpole; 2014, 8, 1; 155-159
1898-617X
2084-4557
Pojawia się w:
Proceedings of ECOpole
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission of the odour substances from fertilizer industry
Autorzy:
Hoffmann, J.
Gryglewicz, G.
Hoffmann, K.
Gryglewicz, S.
Okereke, W.
Skut, J.
Powiązania:
https://bibliotekanauki.pl/articles/779216.pdf
Data publikacji:
2009
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
odory
nawozy mineralne
odours
mineral fertilizers
Opis:
Mineral fertilizers are indispensable for the intensification of plant production in agriculture. This process can cause a significant odour nuisance for the environment due to organic compounds content in apatites and phosphorites converted into fertilizers. The following chemical compounds are emitted to the gas phase among others: hydrogen sulphide, organic sulphides and (methyl, ethyl, isopropyl, butyl) disulphides, chain hydrocarbons, organic oils, waxes and carboxylic acids. A method using gas chromatography analysis with the mass detector (TD-GS-MS), to determine trace concentrations, was developed and tested for the assessment of odour nuisant substances emission from these processes. Application of additional thermal desorber to enable the intense desorption of the investigated organic compounds (previously adsorbed on classical sorbents) in the industrial research has been taken into consideration. In effect it facilitates the accumulating substances to be analyzed at short time interval providing identifying measurements. The technique has been verified during the investigation of the substances emitted in fertilizers processes at Maroko phosphorite decomposition. The organic sulfur compounds, aliphatic and aromatic hydrocarbons have been detected.
Źródło:
Polish Journal of Chemical Technology; 2009, 11, 1; 12-15
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission of Volatile Fluorine Compounds from Partially Acidulated Phosphate Rocks Production Process
Emisja lotnych związków fluoru z procesu otrzymywania fosforytów częściowo rozłożonych
Autorzy:
Hoffmann, K.
Skut, J.
Rybarski, S.
Powiązania:
https://bibliotekanauki.pl/articles/388821.pdf
Data publikacji:
2013
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
phosphate fertilizers
partially acidulated phosphate rocks (PAPR)
volatile fluorine compounds
nawozy fosforowe
fosforyty częściowo rozłożone (PAPR)
lotne związki fluoru
Opis:
Emission of volatile fluorine compounds is considered to be the major environmental concern of the phosphate fertilizers manufacturing process. The results of presented studies indicates that the use of PAPR technology as an alternative to conventional superphosphatic fertilizers reduces F– total emission. For the assumed production capacity of 800 Mg/day of PAPR products a decrease in ηPAPR value from 1.0 (SSP) to 0.3 causes a reduction in F– by average: 6045 → 1675 kg/day and 1545 → 506 kg/day for H2SO4 and H3PO4 respectively as the mineral acids used for acidulation process, while decrease in ηPAPR value from 1.0 (SSP) to 0.5 causes a reduction in F–by average: 6045→1865 kg/day and 1545→660 kg/day for H2SO4 and H3PO4, respectively. Reducing the F– content improves environmental and economic profile of the installation, limits the amount of resulting silica, and allow a reduction in off-gas flow intensity, or spraying density.
Emisja lotnych związków fluoru jest uważana za podstawowe zagrożenie środowiskowe procesów wytwarzania nawozów fosforowych. Rezultaty przeprowadzonych badan wskazuję, że stosowanie technologii PAPR jako alternatywy dla konwencjonalnych nawozów superfosfatowych, powoduje zmniejszenie emisji całkowitej F–. Dla założonej zdolności produkcyjnej 800 Mg/dobę produktów nawozowych typu PAPR obniżenie wartości ηPAPR z 1,0 (SSP) do 0,3 powoduje redukcję F– średnio: 6045 → 1675 kg/dobę oraz 1545→506 kg/dobę dla odpowiednio H2SO4 i H3PO4 jako kwasów mineralnych zastosowanych w procesie roztwarzania; podczas gdy obniżenie wartości ηPAPR z 1,0 (SSP) do 0,5 powoduje redukcję F– średnio: 6045→1865 kg/dobę oraz 1545→660 kg/dobę odpowiednio dla H2SO4 i H3PO4. Obniżenie zawartości F– poprawia profil środowiskowy oraz ekonomiczny instalacji, prowadząc jednocześnie do ograniczenia ilości powstającej krzemionki, pozwalając na zmniejszenie natężenia przepływu gazów odlotowych lub gęstości zraszania.
Źródło:
Ecological Chemistry and Engineering. A; 2013, 20, 12; 1451-1459
1898-6188
2084-4530
Pojawia się w:
Ecological Chemistry and Engineering. A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR and Spectral Studies of a Molecular and Crystal Structure of Cu (3,5-dimethylpyridine)$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{2}$
Autorzy:
Hoffmann, S. K.
Goher, M. A. S.
Hilczer, W.
Goslar, J.
Hafez, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/1930620.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Ea
61.66.-f
76.30.Da
Opis:
X-band single crystal EPR, IR and UV-VIS data are used to deduce a molecular and crystal structure of a new compound with a chemical formula Cu(3,5-dimethylpyridine)$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{2}$. EPR shows that four magnetically inequivalent molecules exist in the crystal unit cell of C$\text{}_{4v}$ symmetry. IR spectra suggested that both monodentate and bidentate NO$\text{}_{3}$-groups exist in the crystal. A most probable Cu(II) complex geometry with d$\text{}_{x²-y²}$ ground state is a square pyramid with three nitrogens from 3,5-dimethylpyridine molecules and one oxygen from monodentate nitrato group in a basal plane and an oxygen from NO$\text{}_{3}$-group in apical position. There exists a chemical contact between complexes as it is indicated by the exchange interaction with |J| ≤ 1 cm$\text{}^{-1}$. It suggests that square pyramid complexes are arranged in polymeric chains with semi-coordination of bidentate NO$\text{}_{3}$-group to the adjacent Cu(II) ion. An extended analysis of an exchange averaging effect between EPR lines from two and four Cu(II) sites is presented with equations relating molecular and crystal g-factors.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 517-530
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Dating of Hydroxyapatite from Fossil Bones. Transient Effects after γ and UV Irradiation
Autorzy:
Wencka, M.
Hoffmann, S. K.
Hercman, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043612.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
65.90.+i
Opis:
ESR measurements at room temperature have been performed on fossil bones of cave bear (from Magurska Cave of the Tatra Mountains) and mammoth (from Dniestr River). Various paramagnetic centres related to defects in hydroxyapatite were identified. The ESR spectrum is dominated by Mn$\text{}^{2+}$ lines and free radical centres CO$\text{}_{2}^{-}$ and CO$\text{}_{3}^{-}$. Suitability of various EPR lines for the dating was evaluated. The spectra are affected by γ-ray and UV irradiation which produce new relatively unstable (transient) radical centres. From their decay curves we determined the delay period (waiting time) between irradiation and ESR dating measurements. For γ-rays the period is about 15 days and depends on the chosen ESR line. UV generates mainly surface O$\text{}^{-}$ centres which decay practically after a few days. The ESR dating of the bear bones using an additive dose method given the age t = 21.7 kiloyears (ky), whereas from radionuclide Th/U method t= 34 ky and from radiocarbon $\text{}^{14}$C method t > 33.1 ky.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 331-337
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ESR and Electron Spin Echo Studies of Spin-Lattice Relaxation of Hydrazinium Radical in Li(N$\text{}_{2}$H$\text{}_{5}$)O$\text{}_{4}$ Single Crystal
Autorzy:
Morawski, P.
Hoffmann, S. K.
Hilczer, W.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964224.pdf
Data publikacji:
1997-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.80.Ed
76.30.Rn
Opis:
A hydrazinium ṄH-NH$\text{}_{3}^{+}$ radical was identified by ESR in γ-irradiated Li(N$\text{}_{2}$H$\text{}_{5}$)SO$\text{}_{4}$ single crystal. Unpaired electron is strongly localized on the nitrogen atom as compared to hydrazinium radicals in other crystals. Angular variations of the multicomponent ESR spectra and computer calculations gave the isotropic hyperfine coupling parameters (in mT): a$\text{}_{N1}$ = 1.93, a$\text{}_{N2}$ = 0.80, a$\text{}_{H1}$ = 2.50, a$\text{}_{H1'}$ = 0.48 (NH$\text{}_{3}$), and a$\text{}_{H2}$ = 1.40 (adjacent molecule). The radiation defects containing unpaired electrons do not influence much the protonic conductivity along the hydrazine molecule chains in the crystal. It confirms a tunelling mechanism of the conductivity activated by NH$\text{}_{2}$-group rotation. Spin-lattice relaxation time T$\text{}_{1}$ varies strongly with temperature in the range from 100 ms (10 K) to 90 μs (170 K) and is governed by spectral diffusion (1/T$\text{}_{1}$ ∝ T$\text{}^{2}$) and a Murphy-type mechanism (1/T$\text{}_{1}$ ∝ cosech(Δ/T)) with Δ = 150 cm$\text{}^{-1}$. A distribution of the spin-relaxation times was observed with temperature independent dispersion parameter β = 0.76.
Źródło:
Acta Physica Polonica A; 1997, 91, 6; 1121-1129
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Aerial Spray Technologies for Adult Mosquito Control Applications
Autorzy:
Hoffmann, W.C.
Fritz, B.K.
Farooq, M.
Walker, T.W.
Czaczyk, Z.
Hornsby, J.
Bonds, J.A.S.
Powiązania:
https://bibliotekanauki.pl/articles/65542.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Spray droplet size has long been recognized as an important variable that applicators of vector control sprays must be aware of to make the most effective spray applications. Researchers and applicators have several different techniques available to assess spray droplet size from spray nozzles. The objective of this study was to compare the droplet size spectrum produced by three nozzles commonly used in vector control in a high-speed wind tunnel, when characterized using three different laser-based droplet size measurement systems. Three droplet sizing systems: Malvern Spraytec laser diffraction, Sympatec HELOS laser diffraction, and TSI Phase Doppler Particle Analyzer (PDPA), were simultaneously operated, but under different operating conditions, to measure the spray droplet size-spectra for three spray nozzles. The three atomizers: a TeeJet® 8001E even flat fan nozzle, a BETE® PJ high pressure fog nozzles, and a Micronair ® AU5000 rotary atomizer were evaluated in a high speed wind tunnel at airspeeds of 53 and 62 m/s (120 and 140 mph). Based on the results of this work, only the BETE® PJ high pressure fog nozzles met the label requirements for both Fyfanon® and Anvil®. While the other nozzle might met the Dv0.5 (VMD - volume median diameter) requirement for Fyfanon®, the resulting Dv0.9 values exceeded labeled size restrictions. When applying Anvil with the BETE PJ high pressure fog nozzles, it is important to use the smaller two orifice sizes. The larger sizes tended to result in Dv0.9 values that exceeded label recommendations.
Źródło:
Journal of Plant Protection Research; 2013, 53, 3
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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