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Search results for: ATOMIC AND MOLECULAR PHYSICS
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Total electron-scattering cross section measurements for tetrahydropyran, (CH2)5O, molecules
PublicationZmierzono całkowity przekrój czynny (TCS) na rozproszenie elektronów na drobinach tetrahydropyranu. Pomiary przeprowadzono metodą transmisyjną w zakresie energii zderzenia 1 - 400 eV. Otrzymana zależność energetyczna TCS wskazuje na obecność procesów rezonansowych w zakresie 3 - 15 eV. Wyniki porównano z całkowitymi przekrojami czynnymi dla drobin tetrahydrofuranu i alkoholu alfa-tetrahydrofurfurylowego.
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Electron collision with sulfuryl chloride (SO2Cl2) molecule
PublicationStosując liniową metodę transmisyjną zmierzono całkowite przekroje czynne (TCS) na zderzenie elektronów z drobinami SO2Cl2 w zakresie energii 0.5-150 eV. Stwierdzono obecność głębokiego minimum przy ok. 1.8 eV i szerokiego maksimum w pobliżu 9.5 eV. Przeprowadzono porównanie z dostępnymi wynikami dla innych związków zawierających grupę sulfonową.
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Electron collision with B(CD3)3 molecules
PublicationArtykuł prezentuje całkowite przekroje czynne na rozpraszanie elektronów na drobinach B(CD3)3 zmierzone dla niskich i średnich energii zderzenia. Wyniki porównano z elastycznymi i jonizacyjnymi przekrojami czynnymi obliczonymi dla drobiny B(CD3)3 dla średnich energii zderzenia. Porównano i przedyskutowano przekroje czynne dla drobin zawierających bor.
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Ionization and fragmentation of furan molecules by electron collisions
PublicationCation mass spectra obtained by electron impact were measured to investigate the ionization and ionic fragmentation of furan, C4H4O, molecules in the gas phase. The most abundant cations, with comparable intensities in the mass spectra, were the parent, C4H4O+, cation (68 amu) and the C3H3+ fragment (39 amu). The appearance energies of most of the observed ionic fragments were determined and the possible fragmentation processes...
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Elimination and migration of hydrogen in the vacuum-ultraviolet photodissociation of pyridine molecules
PublicationElimination of the excited hydrogen atoms H(n), n = 4–7, and hydrogen migration in formation of the excited NH(A 3Π) free radicals in the photodissociation of pyridine, C5H5N, molecules have been studied over the 17.5–70 eV photon energy range. In the measurements the photon-induced fluorescence spectroscopy technique has been applied. Both fragments are produced through excitation of pyridine molecules into higher-lying superexcited...
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Scattering of electrons by a 1,2-butadiene (C4H6) molecule: measurements and calculations
PublicationWe present the results of experimental and theoretical study on electron collisions with a 1,2-butadiene (H2C=C=CHCH3) molecule. Absolute grand-total cross sections (TCSs) were measured using a linear electron-transmission method for collision energies in the 0.5–300 eV range. Two distinct features in the TCS energy curve were detected: a narrow peak located at 2.3 eV and a broad enhancement centered around 9 eV. We attributed...
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Scattering of electrons from acetaldehyde and acetone
PublicationZmierzono całkowity przekrój czynny (TCS) na rozproszenie elektronów na drobinach acetaldehydu (CH3)CHO oraz acetonu (CH3)2CHO w zakresie energii zderzenia 0.7 - 400 eV. Charakter otrzymanych zależności energetycznych TCS jest typowy dla drobin o wysokim momencie dipolowym. Wyniki porównano z przekrojami czynnymi dla izomerów cyklicznych odpowiadających obu drobinom.
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Formation of CN (B2∑+) radicals in the vacuum-ultraviolet photodissociation of pyridine and pyrimidine molecules
PublicationFormation of the excited CN(B2∑+) free radicals in the photodissociation of pyridine (C5H5N) and pyrimidine (C4H4N2) molecules was investigated over the energy ranges 16–27 and 14.7–25 eV, respectively. Photon-induced fluorescence spectroscopy was applied to detect the vibrationally and rotationally excited CN radicals by recording the B2∑+→X2∑+ emission bands (violet system). The measured dissociation yield curves demonstrate...
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Measurements of photoionization of mercury atoms into the 6s 2S1/2, 5d96s2 2D5/2 and 5d96s2 2D3/2 ionic states over the energy range from 10.5 eV to 18.7 eV
PublicationPhotoionization of mercury atoms into the three lowest ionic states, 5d106s 2S1/2, 5d96s2 2D5/2 and 5d96s2 2D3/2 has been studied in the photon energy ranges from their respective thresholds to 18.7 eV. The photoionization spectra were obtained with high energy resolution at an angle of 0° with respect to the polarization vector of the photon beam. The high energy resolution and sensitivity achieved in the measurements permitted...
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Low energy inelastic electron scattering from carbon monoxide: II. Excitation of the b3Σ+, j3Σ+, B1Σ+, C1Σ+ and E1Π Rydberg electronic states
PublicationIn this second part of a two part paper (first part: Zawadzki et al (2020 J. Phys. B: At. Mol. Opt. Phys. 53 165201)) we present differential scattering cross sections for excitation of several Rydberg electronic states of carbon monoxide by electron impact. The first part concerned the low-lying valence states of CO. In the present study cross sections are obtained experimentally using low-energy electron energy-loss spectroscopy...
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Low-energy positron collisions with water: elastic and rotationally inelastic scattering
PublicationDifferential, integral and momentum transfer cross sections for the vibrationally elastic and rotationally inelastic scattering of positrons from water at low collision energy (E ≤ 10 eV) are reported. Several models within the R-matrix method are used to compute the body-fixed T-matrices, while the scattering calculations are performed within the fixed-nuclei approximation corrected with the standard Born-closure formula. These...
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Theoretical and experimental study on scattering of low-energy electrons by dimethyl and diethyl ethers
PublicationWe report a joint theoretical and experimental investigation on low-energy electron scattering by dimethyl and diethyl ethers. The experimental elastic differential cross sections were measured at impact energies from 1 eV up to 30 eV and scattering angle range of 10◦ to 130◦. Theoretical elastic differential, integral and momentum-transfer cross sections are calculated at impact energies up to 30 eV, employing the Schwinger multichannel...
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Low energy inelastic electron scattering from carbon monoxide: I. excitation of the a3Π, a’3Σ+ and AΠ1 electronic states.
PublicationDifferential scattering cross sections for electron excitation of the three lowest excited electron states of carbon monoxide are obtained experimentally using low-energy electron energy-loss spectroscopy and theoretically using the R-matrix method. The incident electron energies range from near-threshold of 6.3 eV to 20 eV. Experimental scattering angles range from 20◦ to 120◦. The normalization of the experimental cross sections...
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Born–Oppenheimer potential energy curves of NaK from the optimised atomic basis sets
PublicationThe article presents adiabatic potential energy curves of the ground and excited electronic states for the diatomic NaK molecule. The calculations were made using the ab initio computational methods to include electron correlation. The studied molecule was calculated as the effective two-electron problem, in which only the valence electrons of the molecule are explicitly taken into account. The remaining electrons with atomic nuclei...
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Anion–water interactions of weakly hydrated anions: molecular dynamics simulations of aqueous NaBF4 and NaPF6
PublicationIn aqueous ionic solutions, both the structure and the dynamics of water are altered dramatically with respect to the pure solvent. The emergence of novel experimental techniques makes these changes accessible to detailed investigations. At the same time, computational studies deliver unique possibilities for the interpretation of the experimental data at the molecular level. Here, using molecular dynamics simulations, we demonstrate...
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Molecular properties with dual basis set methods
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Beyond the helium buffer: 12C−2 rotational cooling in cold traps with H2 as a partner gas: interaction forces and quantum dynamics
Publicationabstract = { The scattering cross-sections and corresponding rate coefficients for rotationally inelastic collisions of $^{12}$C$_2$^-$ ($^2 \Sigma_g^+$) with H$_2$ ($^1 \Sigma_g^+$) are presented over a broad range of cold-trap temperatures. They have been calculated using quantum scattering theory that employs a new ab initio potential energy surface. The rate coefficients for the inelastic processes in the anionic partner are...
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Mixed, quantum-classical description of electron density transfer in the collision process
PublicationIn this work, we investigate an ion-atom model describing the time-dependent evolution of electron density during the collision. For a S3+- H system, numerical simulations are based on classical trajectory calculations, and the electron density behaviour is described with the time-dependent Schrödinger equation. We apply the finite difference method to obtain quantitative insights into the charge transfer dynamics, providing detailed...
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Lithium ion insertion into poly(3,4-ethylenedioxythiophene) films from propylene carbonate electrolytes.
PublicationPolimerowa matryca złożona z poli(3,4-etylenodioksytiofenu z poli(styrenosulfonianem) otrzymana została na drodze syntezy elektrochemicznej. Transport jonowy w matrycy polimerowej w kontakcie z węglanem propylenu zawierającym LiClO4 został scharakteryzowany za pomocą metody impedancji ac oraz chronowoltoamperometrii. Wyznaczono przewodność jonową matrycy oraz efektywne współczynniki dyfuzji dla kationu Li+. Wielkości te...
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Comparison of two approaches to potential of mean force calculations of hydrophobic association: particle insertion and weighted histogram analysis methods
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Relativistic calculations of X-ray photoelectron spectra and the accuracy of the IOTC method*
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Towards an understanding of the nature of superhalogen anions: anab initiostudy of the system
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Are HBO−and BOH−electronically stable?
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The PF6−n(R)n−anions (R = CH3, C2H5;n= 0–6): the dependence of the electronic stability on the number of non-electronegative alkyl ligands
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Thymine dimer repair by electron transfer from photo-excited 2′,3′,5′-tri-O-acetyl-8-oxo-7,8-dihydroguanosine or 2′,3′,5′-tri-O-acetyl-ribosyluric acid – a theoretical study
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Gas-phase quasi-degeneracy of zwitterionic and canonical tautomers of glycine and proline induced by the presence of the MAlF4(M = Li, Na, K) salts
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Dipole-driven dynamics for near-threshold electron/positron interactions with pyrimidinic DNA bases: a path to compound formations
PublicationCalculations are reported for electron and positron scattering from isolated cytosine and thymine, where the two pyrimidinic single-ring DNA bases, in the gas-phase at energies near the elastic threshold, they reveal the special features of the dipole-driven scattering states. All molecules examined exhibit, in fact, supercritical (>1.67 D) permanent dipoles which can therefore also support, below threshold, excited bound compound...
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Predicting the viscosity and electrical conductivity of ionic liquids on the basis of theoretically calculated ionic volumes
PublicationSelected physical properties of the ionic liquids might be quantitatively predicted based on the volumes of the ions these systems are composed of. It is demonstrated that the ionic volumes calculated using relatively simple theoretical quantum chemistry methods can be utilised to estimate the viscosities and electrical conductivities of various commonly used ionic liquids. The fitting formulas of the exponential form are offered...
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Cross sections for electron collision with pyridine [C5H5N] molecule
PublicationThe absolute grand -total cross section (TCS) for electron scattering from pyridine, C5H5N, molecules has been measured at impact energies from 0.6 to 300 eV in the linear electron-transmission experiment. The obtained TCS energy dependence appears to be typical for targets of high electric-dipole moment; the cross section generally decreases with rising energy, except for the 3–20 eV range, where a broad enhancement peaked near...
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Ionic conductivity in bismuth silicate glasses.
PublicationZbadano właściwości elektryczne szkieł krzemianowo- bizmutowych zawierających 55 mol% tlenku bizmutu. Uzyskane wyniki potwierdzają jonowy charakter przewodnictwa, za które odpowiedzialne są jony tlenu.
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Spectral dependences of photocurrent of the aluminium-nickel phthalocyanine-tetracene-aluminium heterojunction
PublicationAnalizowano charakterystyki spectralne fotoprądu płynącego przez heterozłącze tetracen-ftalocyjanina niklu. Obserwowany fotoprąd jest prądem dziurowym generowanym w trzech obszarach: w pobliżu obu elektrod Al i międzypowierzchni tetracen-ftalocyjanina niklu.
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Computer study of the lead-germanium alloy formation in over-reduced lead-germanate glass
PublicationPraca poświęcona jest badaniom dynamiczno-molekularnym struktury zredukowanego szkła ołowiowo-germanianowego o składzie 1Pb 1Ge 1GeO2. Analizie poddano strukturę matrycy szkła, GeO2 i osadzonej w niej fazy metalicznej, którą formują neutralne atomy Pb i Ge.
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Dependence of the charge carries photogeneration yield on the bimolecular recombination in tetracene layers
PublicationBadano mechanizmy generacji nośników ładunku dwóch znaków w warstwie tetracenu. Rezultaty pomiarów doświadczalnych oraz prowadzona analiza wykazały, że rekombinacja wpływa znacząco na produkcję nośników ujemnych.
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Theoretical analysis of current induced by high-energetic radiation in dielectric materials
PublicationW pracy poddano analizie mechanizmy generacji i rekombinacji nośników ładunku w obecności wysokoenergetycznego promieniowania. Przedstawiono zależności gęstości prądu elektrycznego od natężenia promieniowania i napięcia polaryzujacego próbkę.
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The bismuth atom neighbourhood in bismuth-silicate glasses from X-ray absorption experiment
PublicationPraca zawiera wyniki strukturalnej analizy EXAFS lokalnego otoczenia atomów bizmutu w krystalicznym tlenku bizmutu (odmiana alfa) i w szklach bizmutowo-krzemianowych o składzie xBi2O3 (1-x)SiO2,x=0.3, 0.4, 0.5, 0.6. Analizę XA- FS realizowano w oparciu o metodę GNXAS. Otrzymane wyniki porównano z danymi literaturowym.
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Electrical conductivity of reduced lead-germanate glasses
PublicationPewna grupa szkieł tlenkowych poddana procesowi redukcji w atmosferze gorącego wodoru wykazuje gwałtowne zmiany swoich właściwości elektrycznych i optycznych. Szkła ołowiowo-germanianowe, którym poświęcona jest niniejsza praca należą do takich szkieł i charakteryzują się szczególnymi redukcyjnie indukowanymi właściwościami. Wystarczająco długie wygrzewanie prowadzi bowiem do wzrostu przewodnictwa elektrycznego nawet o 12 rzędów...
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Modulated photocurrents in amorphuous solids uner varius experimwntal conditions
PublicationPodobno przybliżone wzory opisujące modulowane fotoprądy mierzone w słaboprzewodzących próbkach o kanapkowym układzie elektrod. Pokazano wpływ zapełnienia pułapek, głębokości absorpcji światła i dyfuzji w próbce na teoretyczne przebiegi fotoprądów. Zamieszczono przykładowe krzywe fotoprądów, zmierzone w poli(N-winylokarbazolu) i otrzymane na ich podstawie energetyczne rozkłady gęstości pułapek dla dziur.
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Influence of the annealing conditions on the resistivity of Nd2CuO4 singlecrystals
PublicationW pracy wyznaczono temperaturową zależność oporności w płaszczyźnie ab dla dwóch grup kryształów Nd2CuO4 w zakresie 50-300 K.
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GaAs-Si interfacial energy determination
PublicationBazując na półempirycznym modelu wiązań kowalencyjnych w krzemie wyznaczono energie międzypowierzchni GaAs-Si. Obliczona energia międzypowierzchni GaAs-Si zależna jest od orientacji podłoża Si. Minimalna energia międzypowierzchniowa wyznacza odpowiednią konfigurację atomów w pobliżu powierzchni, która określa optymalne warunki heteroepitaksji GaAs na podłożach Si.
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Experimental and theoretical study of protonated water cluster
PublicationZa pomocą metody rojowej zbadano powstanie i dryf dodatnio naładowanych klastrów wody H+(H20)n n=1-7. Oszacowano energie dysocjacji. Prace uzupełniają obliczenia kwantowe konfiguracji wybranych klastrów. Dokonano obliczeń kilkunastu konfiguracji zjonizowanych klastrów.
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Positron Annihilation Studies of Silicon Oxides and Oxygen Precipitates in Silicon
PublicationTechniki pozytonowe dają możliwości badania defektów i zmian strukturalnych nie obserwowanych innymi metodami. W tej pracy zastosowano 3 różne techniki pozytonowe do badania zmian strukturalnych i tworzenia wydzieleń SiOx w krzemie.
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Paweł Możejko dr hab.
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Radosław Szmytkowski prof. dr hab.
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Jan Franz dr hab.
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Piotr Jamroz dr hab. inż.
PeoplePiotr Jamroz graduated from Wroclaw University of Technology, Faculty of Chemistry in 1998 and obtained his PhD from the same university in 2003. Currently he works as an associate professor at Wroclaw University of Science and Technology, Faculty of Chemistry, Division of Analytical Chemistry and Chemical Metallurgy. His research interests are related to generation and diagnostics of different kinds of plasma sources, including...
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Electron-impact dissociation of molecular hydrogen: benchmark cross sections
PublicationWe present a joint experimental and theoretical investigation of a fundamental process in atomic and molecular physics: electron impact excitation of molecular hydrogen’s (H2) most dominant transition (X1Σg+ → b3Σu+). Excitation of this state is by far the main channel that causes the dissociation of H2 into H + H atoms at low energies. The Convergent Close-Coupling (CCC) calculations predicted significant, more than factor of...
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Interactions of positrons with atoms and molecules
PublicationThe positron is the antiparticle of the electron. It has the same mass as the electron, but opposite charge. The understanding of the interactions of positrons with normal matter, like atoms and molecules, is of interest in various scientific fields, like nuclear medicine, plasma physics and astronomy. In this talk we will give a short introduction to some theoretical methods to describe the interactions of positrons with atoms...
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Multi-GPU-powered UNRES package for physics-based coarse-grained simulations of structure, dynamics, and thermodynamics of protein systems at biological size- and timescales
PublicationCoarse-grained models are nowadays extensively used in biomolecular simulations owing to the tremendous extension of size- and time-scale of simulations. The physics-based UNRES (UNited RESidue) model of proteins developed in our laboratory has only two interaction sites per amino-acid residue (united peptide groups and united side chains) and implicit solvent. However, owing to rigorous physics-based derivation, which enabled...
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Rengel Cane Sia Doctoral Candidate
PeopleI'm Rengel, born and raised in the Philippines. As an undergraduate I did kinetic modeling on Copper-catalyzed atom transfer radical addition (ATRA). Then I was inspired to do both theoretical and experimental studies, which led me to propose my master's thesis on Synthesis, Computational, Electrochemical, and Photoconductivity Studies on Naphthalene and its derivatives. This led to a master's degree in Chemistry in the Mindanao...
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Potential energy curves, transition and permanent dipole moments of KRb
PublicationWe present extensive calculations of 48 adiabatic potential energy curves of the KRb molecule. Efforts have been focused on preparing the appropriate basis sets. Compared to previous approaches, the set of new potential energy curves is extended to higher excitations, including the single-excited K(4s2S)+Rb(5d2D) and double-excited K(4p2P)+Rb(5p2P) atomic limits. Larger distances between nuclei are also taken into account. New...