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Search results for: electron paramagnetic resonance
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Electron scattering from tin tetrachloride (SnCl4) molecules
PublicationAbsolute grand-total cross section (TCS) for electron scattering from a tin tetrachloride, SnCl4, molecule was measured at electron-impact energies ranging from 0.6 to 300 eV, in the linear electron-transmission experiment. The measured TCS energy dependence shows two very pronounced enhancements peaking near 1.2 eV and around 9.5 eV, separated with a deep minimum centered close to 3 eV. The low energy structure is attributed to...
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Electron-impact ionization cross section calculations for selected ribonucleosides
PublicationTotal cross sections for the single electron-impact ionization of selected ribonuclosides (guanosine, adenosine, cytidine and uridine) have been calculated for electron energies ranging from the ionization threshold up to 5 keV.
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A Novel Ru(II) Polypyridine Black Dye Investigated by Resonance Raman Spectroscopy and TDDFT Calculations
PublicationThe optical properties of a new(bipyridine)2Ru(4H-imidazole) complex presenting a remarkablebroad absorption in the visible range are investigated. Thestrong overlap of the absorption with the solar radiationspectrum renders the studied complex promising as a blackabsorber and hence as a starting structure for applications inthe field of dye-sensitized solar cells. The correlations betweenstructural and electronic features for...
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Electron mobility variance in semiconductors: the variance approach
PublicationPraca przedstawia nowe podejście da analizy zjawisk losowych w półprzewodnikach. Uwzględnia kilka mechanizmów zjawisk fluktuacji ruchliwości w półprzewodnikach, prowadzących do powstawamai składowej szumów typu 1/f, dominujących w zakresie małych czetotliwości. Przedstawia analizę sposobu wyznaczenia stałej Hooge'a określającej intensywność szumów typu 1/f.The statistical non-triviality of current carrier mobility fluctuations...
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Low energy elastic electron scattering from benzonitrile (C6H5CN)
PublicationWe present experimental differential elastic scattering cross sections (DCSs) for low energy electron scattering from benzonitrile along with integral and momentum-transfer cross sections that are determined from these DCSs. The measurements of DCSs are obtained using the relative flow method with helium as the standard gas, in a crossed electron-molecular gas beam arrangement. Our measurements are made at incident electron energies...
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CROSS SECTIONS CALCULATIONS FOR ELECTRON SCATTERING FROM RHODANINE AND CYANOACETIC ACID
PublicationCross sections for electron-impact ionization and for elastic electron scattering for rhodanine (C3H3NOS2) and cyanoacetic acid (C3H3NO2) have been calculated in wide impinging electron energy range.
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Electron attachment to representative cations composing ionic liquids
PublicationUsing ab initio electronic structure methods with flexible atomic orbital basis sets, we investigated the electronic structure and stability of reduction products of selected representative cations (C+) constituting ionic liquids. We found that an electron attachment to such cations leads to the neutral radicals, whereas a subsequent attachment of another (i.e., excess) electron leads to adiabatically stable anions only in two...
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Magnetic Resonance Insights
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Magnetic Resonance in Solids
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MAGNETIC RESONANCE IN MEDICINE
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APPLIED MAGNETIC RESONANCE
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Opposite pressure impact on electron-phonon coupling in Eu2+ and Ce3+ doped AlN
Open Research DataThis data analyzes the influence of pressure on electron–lattice interactions in the 5d excited states of Ce3+ and Eu2+ in the AlN host based on pressure-dependent photoluminescence and photoluminescence excitation spectra. High-pressure measurements on AlN samples doped with Eu2+ and Ce3+ ions reveal that the Stokes shift increases with pressure for...
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Electron impact ionization and cationic fragmentation of the pyridazine molecules
PublicationElectron impact mass spectroscopy was used to investigate ionization and cationic fragmentation of the pyridazine (1,2 diazine), C4H4N2, molecules in the gas phase. The mass spectra were measured and the observed mass peaks assigned to the corresponding cations. The appearance energies of most of the cationic fragments were determined and the possible fragmentation processes are discussed. The total cross section for electron...
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Dissociative electron attachment and anion-induced dimerization in pyruvic acid
PublicationWe report partial cross sections for the dissociative electron attachment to pyruvic acid. A rich fragmentation dynamics is observed. Electronic structure calculations facilitate the identification of complex rearrangement reactions that occur during the dissociation. Furthermore, a number of fragment anions produced at electron energies close to 0 eV are observed, that cannot originate from single electron-molecule collisions....
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Dehydrogenation in electron-induced dissociative ionization of pyridine molecule
PublicationThe electron-impact dissociative ionization of pyridine has been investigated using mass spectrometry. Thirty-two well-resolved mass peaks have been identified in the cation mass spectra and assigned to the most likely ionic molecular fragments. The new sixteen ionic fragments' appearance energies have been determined, and sixteen others remeasured. The total cross-section for electron-impact ionization of pyridine has been measured...
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Sum-over-state expressions including second-order Herzberg–Teller effects for the calculation of absorption and resonance Raman intensities
PublicationThe sum-over-state expressions are derived to calculate the second-order Herzberg–Teller (HT) effects in absorption and resonance Raman spectroscopies. These effects depend on the second derivatives of the transition dipole moment with respect to the vibrational coordinates. The method is applied to the molecule of 1,3-butadiene using density functional theory calculations. It is found that the second-order HT effects are significant...
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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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Modeling of TiO2-Based Electron-Selective Contacts for Crystalline Silicon Solar Cells
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A study of the electronic states of pyrimidine by electron energy loss spectroscopy
PublicationThe electron energy loss spectra were measured in pyrimidine at the constant electron residual energy varied from 15 meV to 10 eV and in the scattering angle range 0–180°. The spectra were analysed applying an iteration fitting procedure to resolve the energy loss bands corresponding to excitation of the electronic states of pyrimidine. The vertical excitation energies of the singlet states of pyrimidine and of a number of the...
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Anionic states of C6Cl6 probed in electron transfer experiments
PublicationThis is the first comprehensive investigation on the anionic species formed in collisions of fast neutral potassium (K) atoms with neutral hexachlorobenzene (C6Cl6) molecules in the laboratory frame range from 10 up to 100 eV. In such ion-pair formation experiments, we also report a novel K+ energy loss spectrum obtained in the forward scattering giving evidence of the most accessible electronic states. The vertical electron affinity...
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Electron energy-loss spectroscopy of excited states of the pyridine molecules
PublicationElectron energy-loss spectra of the pyridine, C5H5N, molecules in the gas phase have been measured to investigate electronic excitation in the energy range 3.5–10 eV. The applied wide range of residual electron energy and the scattering angle range from 10 ◦ to 180 ◦ enabled to differentiate between optically-allowed and -forbidden transitions. These measurements have allowed vertical excitation energies of the triplet excited...
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A first-principles study of electron attachment to the fully hydrated bromonucleobases
PublicationDegradation mechanism of four brominated nucleobases (BrX), potential DNA radiosensitizers, is studied in explicit water solution, using ab initio molecular dynamics. Several fs long dynamics is needed to localize an electron on the nucleobase. Produced by electron attachment BrX anion radical degrades through the bromide anion abstraction, barrier-free (purines) or with low barrier (pyrimidines), to a reactive nucleobase radical....
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First detection of spectral resonance structures of the ionospheric Alfvén resonance in ULF/ELF magnetic field recorded at Suwałki, Poland
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Resonance Raman Study on Carbon Nanotubes Formation
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Investigations of resonance effects during silo flow.
PublicationOmówiono problem efektów rezonansowych podczas przepływu materiału sypkiego w silosie. Wykonano badania doświadczalne w dużych i małych silosach. Obliczenia MES wykonano dla płaskiego stanu odkształcenia. Zachowanie materiału sypkiego było modelowane mikropolarnym sprężysto-plastycznym prawem wg Mh hausa. W obliczeniach uwzględniono wpływ ścian. Wyniki numeryczne porównano z doświadczeniami w dużych i małych silosach.
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Correlation–polarization effects in electron/positron scattering from acetylene: A comparison of computational models
PublicationDifferent computational methods are employed to evaluate elastic (rotationally summed) integral and differential cross sections for low energy (below about 10 eV) positron scattering off gas-phase C2H2 molecules. The computations are carried out at the static and static-plus-polarization levels for describing the interaction forces and the correlation–polarization contributions are found to be an essential component for the correct...
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ELECTRON-IMPACT IONIZATION CROSS SECTIONS CALCULATIONS FOR PURINE AND PYRIMIDINE MOLECULES
PublicationCross sections for electron-impact ionization of purine and pyrimidine molecules have been calculated using binary-encounter-Bethe method for electron energies ranging from the ionization threshold up to 5 keV. Ionization cross section for purine molecules is 1.4 times higher than for pyrimidine molecules. Acceptable agreement between experimental and theoretical ionization data for pyrimidine molecule has been found.
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Recent total cross section measurements in electron scattering from molecules
PublicationThe grand-total cross sections (TCSs) for electron scattering from a range of molecules, measured over the period 2009-2019 in various laboratories, with the use of different electron transmission systems, are reviewed. Where necessary, the presented TCS data are also compared to earlier results. Collection of investigated molecular targets (biomolecules, biofuels, molecules of technological application,hydrocarbons) reflects their...
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CONCEPTS IN MAGNETIC RESONANCE PART B-MAGNETIC RESONANCE ENGINEERING
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Electron interactions with Bis(pentamethylcyclopentadienyl) titanium(IV) dichloride and difluoride
PublicationWe present a combined experimental and theoretical study of the interaction of electrons with Bis(pentamethylcyclopentadienyl)titanium(IV) dichloride (Cp∗2TiCl2) and difluoride (Cp∗2TiF2). We report the experimental measurements of partial cross sections for the dissociative electron attachment (DEA) and the electron ionization (EI) mass spectra of isolated molecules. Estimates of the absolute cross sections are done on the basis...
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Electron impact iozization of CCl4 and SF6 embedded in superfluid helium droplets
PublicationElectron impact ionization of helium nano-droplets containing several 104 He atoms and doped with CCl4 or SF6 molecules is studied with high-mass resolution. The mass spectra show significant clustering of CCl4 molecules, less so for SF6 under our experimental conditions. Positive ion efficiency curves as a function of electron energy indicate complete immersion of the molecules inside the helium droplets in both cases. For CCl4...
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An excess electron bound to urea. III. The urea dimer as an electron trap
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Cross section calculations for electron scattering from platinum chemotherapeutic compounds
PublicationCross section for electron impact ionization of carboplatin, C6H12N2O4Pt, and oxaliplatin, C8H14N2O4Pt, have been calculated within binary-encounter-Bethe model for energies from the ionization threshold up to 5000 eV. Cross section for elastic electron scattering from carboplatin and oxaliplatin molecules have also been derived using independent atom method (IAM) and additivity rule for collision energies ranging from 50 eV to...
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Electron collisions with X(CH3)4 molecules (X = C, Si, Ge)
PublicationAbsolute grand-total cross sections (TCSs) for electron scattering from tetramethylmethane [C(CH3)4], tetramethylsilane [Si(CH3)4], and tetramethylgermane [Ge(CH3)4] molecules have been measured at electron-impact energies extending from around 0.5 to 300 eV in the linear electron-transmission experiment. The measured TCS energy dependences show very pronounced broad enhancement, peaking near 5.5 eV for Si(CH3)4 and Ge(CH3)4 molecules...
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Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2′-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment
PublicationWhen modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-20 -deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry...
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Ionization and ionic fragmentation of tetrahydrofuran molecules by electron collisions
PublicationElectron impact ionization and ionic fragmentation of tetrahydrofuran molecules in the gas phase were studied in the energy range from ionization threshold up to 150 eV using the technique of mass spectrometry. The cation mass spectra, ionization and ionic fragmentation efficiencies were measured over this energy range. Well-resolved mass peaks were detected in the mass range 10-72 amu and assigned to corresponding ionic molecular...
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Electron-scattering cross sections for selected alkyne molecules: Measurements and calculations
PublicationWe report cross-section results from experimental and theoretical studies on electron collisions with 1-butyne (HC≡C–CH2CH3) and acetylene (HC≡CH) molecules and from computations for a propyne (HC≡C–CH3) molecule. Absolute grand -total electron-scattering cross sections (TCSs) were measured at impact energies ranging from about 0.5 to 300 eV using the linear electron-transmission method. The TCS energy curve for 1-butyne has a...
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Boron doped Nanocrystalline Diamond-Carbon Nanospike Hybrid Electron Emission Source
PublicationElectron emission signifies an important mechanism facilitating the enlargement of devices that have modernized large parts of science and technology. Today, the search for innovative electron emission devices for imaging, sensing, electronics, and high-energy physics continues. Integrating two materials with dissimilar electronic properties into a hybrid material is an extremely sought-after synergistic approach envisioning a...
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Comparison of PM10 concentration in Gdansk and London using electron microscopy
PublicationParticulate matter (PM) has been considered as one of the most dangerous elements of air pollution. Multiply analytical methods are employed to identify the composition of particles present in the air. The theoretical part of this work is a description of different research centres all over the world where particulate matter is being analyzed using various techniques. The purpose of this project is to analyze and compare particles...
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Electronic states of tetrahydrofuran molecules studied by electron collisions
PublicationElectronic states of tetrahydrofuran molecules were studied in the excitation energy range 5.5-10 eV using the technique of electron energy loss spectroscopy in the gas phase. Excitation from the two conformations, C2 and Cs, of the ground state of the molecule are observed in the measured energy loss spectra. The vertical excitation energies of the 3(no3s) triplet state from the C2 and Cs conformations of the ground state of the...
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IEEE Journal of the Electron Devices Society
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Cross sections for ionization and ionic fragmentation of pyrimidine molecules by electron collisions
PublicationThe electron impact mass spectroscopy and the total ion collection measurements were used to investigate the ionization and ionic fragmentation of the pyrimidine, C4H4N2, molecules in the gasphase. The cation mass spectra were measured in the 10−85 amu range and the observed mass peaks assigned to corresponding ionic fragments. The most abundant cation in the mass spectra is the parent cation, C4H4N+2, at 80 amu. The appearance...
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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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Reply to Comment on ‘Nanodiamond incorporated human liver mimicking phantoms: prospective calibration medium of magnetic resonance imaging’
PublicationDependence of the spin–lattice (T1) relaxation times on the nanodiamond concentration in human liver phantoms is discussed. Factors affecting stability and and reproducibility of these phantoms are presented. The need for comparative measurements on multiple MRI scanners for better understanding of potential variations in the obtained imaging data is emphasised.
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DFT study of low-energy electron interaction with pyridine, pyrazine and their halo derivatives
PublicationIn this work, the density functional theory with B3LYP hybrid functional was employed to calculate quantities useful for estimating the behavior of pyridine, pyrazine and their derivatives monosubstituted with Cl or Br atom, when exposed to low-energy electron impact. Vertical electron affinities obtained in several Pople basis sets and in aug-cc-pVTZ basis set are reported. Although some of the investigated molecules do not form...
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Iridium 5d -electron driven superconductivity in ThIr3
PublicationA polycrystalline sample of superconducting ThI r 3 was obtained by arc-melting Th and Ir metals. Powder x-ray diffraction revealed that the compound crystalizes in a rhombohedral crystal structure (R-3m, s.g. #166) with the lattice parameters: a = 5.3394 ( 1 ) Å and c = 26.4228 ( 8 ) Å . Normal and superconducting states were studied by magnetic susceptibility, electrical resistivity, and heat capacity measurements. The results...
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Enhancing electrochemical properties of an ITO-coated lossy-mode resonance optical fiber sensor by electrodeposition of PEDOT:PSS
PublicationA sensor working in multiple domains may offer enhanced information about the properties of an investigated analyte, including those containing biological species. It has already been shown that a dual-domain sensing capability, i.e., in optical and electrochemical domains, can be offered by lossy-mode resonance (LMR) sensors based on indium-tin-oxide (ITO) thin film. The spectral response of the LMR sensors depends on the refractive...
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Cross sections calculations for electron scattering from dimethylamine, NH(CH3)2, molecule
PublicationThe total cross section for single electron-impact ionization and the integral elastic cross section for electron scattering from dimethylamine have been calculated using the binary-encounter-Bethe model and the independent atom method, respectively.
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Shape resonance of the ethylene anion stabilized in a molecular trap
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Spontaneous electron emission vs dissociation in internally hot silver dimer anions
PublicationReferring to a recent experiment, we theoretically study the process of a two-channel decay of the diatomic silver anion (Ag2-), namely the spontaneous electron ejection giving Ag2 + e- and the dissociation leading to Ag- + Ag. The ground state potential energy curves of the silver molecules of diatomic neutral and negative ion were calculated using proper pseudo-potentials and atomic basis sets. We also estimated the non-adiabatic...