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Search results for: Electron collision spectroscopy of atoms and molecules
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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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Interactions of protons with furan molecules studied by collision-induced emission spectroscopy at the incident energy range of 50–1000 eV
PublicationInvestigations of the ion-molecule reactions provide insight into many fields ranging from the stellar wind interaction with interstellar media, up to medicine and industrial applications. Besides the applications, the understanding of these processes is itself a problem of fundamental importance. Thus, interactions of protons with the gas-phase furan molecules have been investigated for the first time in the energy range of 50–1000...
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Charge Transfer, Complexes Formation and Furan Fragmentation Induced by Collisions with Low-Energy Helium Cations
PublicationThe present work focuses on unraveling the collisional processes leading to the fragmentation of the gas-phase furan molecules under the He+ and He2+ cations impact in the energy range 5–2000 eV. The presence of different mechanisms was identified by the analysis of the optical fragmentation spectra measured using the collision-induced emission spectroscopy (CIES) in conjunction with the ab initio calculations. The measurements of...
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Positron-electron correlation-polarization potentials for the calculation of positron collisions with atoms and molecules
PublicationWe present correlation-polarization potentials for the calculation of scattering cross sections of positrons with atoms and molecules. The potentials are constructed from a short-range correlation term and a long-range polarization term. For the short-range correlation term we present four different potentials that are derived from multi-component density functionals. For the long-range polarization term we employ a multi-term...
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Charge transfer and formation of complexes in the He+ collisions with the furan molecules
PublicationCharge transfer and formation of the collision complexes have been studied experimentally in fragmentation of the furan molecules in collisions with He+ cations. The excited atomic and diatomic fragments of furan have been identified using collision-induced luminescence spectroscopy. Charge transfer ionization of the furan molecules has been observed in production of helium atoms in the excited 1s4d 1D2, 3D1,2,3 states. The fragmentation...
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Electron Scattering on X(CH3)4 Molecules: Applicability of Simple Additivity Rule and Role of Methylation
PublicationTo investigate influence of target methylation (substitution of a hydrogen atom by methyl group) on electron-collision processes we compare absolute total cross sections for XH4 and X(CH3)4 molecules, where X is Si and Ge, respectively. We also compare experimental TCSs energy dependencies with estimated data obtained using simple formula and TCSs for methyl group and those for SiH4 and GeH4. Electron-scattering TCSs for mentioned...
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Optoelectronic system for investigation of cvd diamond/DLC layers growth
PublicationDevelopment of the optoelectronic system for non-invasive monitoring of diamond/DLC (Diamond-Like-Carbon) thin films growth during μPA ECR CVD (Microwave Plasma Assisted Electron Cyclotron Resonance Chemical Vapour Deposition) process is described. The system uses multi-point Optical Emission Spectroscopy (OES) and long-working-distance Raman spectroscopy. Dissociation of H2 molecules, excitation and ionization of hydrogen atoms...
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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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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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Optoelectronic system for monitoring of thin diamond layers growth
PublicationDevelopment of the optoelectronic system for monitoring of diamond/DLC (Diamond-Like-Carbon) thin films growth during mu PA ECR CVD (Microwave Plasma Assisted Electron Cyclotron Resonance Chemical Vapour Deposition) process is described. The multi-point Optical Emission Spectroscopy (OES) and Raman spectroscopy were employed as non-invasive optoelectronic tools. Dissociation of H-2 molecules, excitation and ionization of hydrogen...
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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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Fragmentation of Tetrahydrofuran Molecules by H+, C+, and O+ Collisions at the Incident Energy Range of 25–1000 eV
PublicationWe have studied fragmentation processes of the gas-phase tetrahydrofuran (THF) molecules in collisions with the H+, C+, and O+ cations. The collision energies have been varied between 25 and 1000 eV and thus covered a velocity range from 10 to 440 km/s. The following excited neutral fragments of THF have been observed: the atomic hydrogen H(n), n = 4–9, carbon atoms in the 2p3s 1P1, 2p4p 1D2, and 2p4p 3P states and vibrationally...
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Photofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region via superexcited states studied by fluorescence spectroscopy
PublicationPhotofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region, producing excited atomic and molecular fragments, has been studied over the energy range 14-68 eV using photon-induced fluorescence spectroscopy. Excited hydrogen atoms H(n), n = 3-11, have been detected by observation of the Hα to Hı lines of the Balmer series. The diatomic CH(A2Δ), CH(B2Σ-) and C2(d3Πg) fragments, which are excited to low vibrational...
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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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Electron energy-loss spectroscopy of excited states of the diazine molecules: Pyridazine
PublicationExcitation of the valence electronic states of the pyridazine molecules in the gas phase have been studied using the technique of electron energy-loss spectroscopy. Varying the electron scattering conditions, the residual electron energy and scattering angle, enabled the optically-allowed and -forbidden excitations to be differentiated. The measured energy-loss spectra enabled the vertical excitation energies of the observed states...
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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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Formation of OH Radicals as Evidence of Intramolecular Hydrogen Migration in Cation-Induced Dissociation of Furan Molecules
PublicationWe present the experimental results on a hydrogen atom migration preceding fragmentation of the furan molecules induced by the H3+ and C+ impact. The excited OH(A2Σ+) radical has been detected among the furan decomposition products using collision-induced emission spectroscopy. However, the OH moiety is absent in the furan ring skeleton, so detecting the OH(A2Σ+→X2Π) luminescence indicates the intramolecular H atom relocation prior...
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Hydration of Oxometallate Ions in Aqueous Solution
PublicationThe strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds...
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Optical Spectroscopic Studies of Tetrahydrofuran Fragmentation Induced by Collisions with Dihydrogen Cations
PublicationCollisions of dihydrogen cations with tetrahydrofuran molecules have been studied. Luminescence spectra and the emission functions of the excited products at projectile energies ranging from 8 to 1000 eV have been measured using collision-induced emission spectroscopy. The recorded spectra are dominated by the atomic lines of the hydrogen Balmer series, whose intensities decrease more quickly than derived by the quantum-theoretical...
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Collision-induced luminescence spectra of pyridine bombarded by 1000 eV He+ cations
PublicationHere we show collision-induced luminescence spectra measured for collisions of the He+cations with thearomatic six-membered ring of the pyridine molecule (C5H5N). Distinct emission bands due to the CH(A2Δ→X2Πr;B2Σ+→X2Πr;C2Σ+→X2Πr), CN(B2Σ+→X2Σ+), C2(d3Πg→a3Πu), and NH(A3Π→X3Σ−) transitions, aswell as atomic H, He, and C lines have been observed. Apart from the He atoms, all the emitters arise from thefragmentation of the pyridine...
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A Comprehensive Experimental and Theoretical Study on the[{(η5-C5H5)2Zr[P(µ-PNEt2)2P(NEt2)2P]}2O Crystalline System
PublicationThe structure of tetraphosphetane zirconium complex C52H100N8OP10Zr21 was determined by single crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c, with a = 19.6452(14), b = 17.8701(12), c = 20.7963(14)Å, α = γ = 90°, β = 112.953(7)°, V = 6722.7(8)Å3, Z = 4. The electronic structure of the organometallic complex has been characterized within the framework of Quantum Chemical Topology....
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[N,N'-Bis(2,6-diisopropylphenyl)pentane-2,4-diamine(1-)-2[kappa]2N,N']-[mu]2-chlorido-1:2[kappa]2Cl:Cl-chlorido-2[kappa]Cl-bis(1,2-dimethoxyethane-1[kappa]2O,O')iron(II)lithium
PublicationIn the title compound, [FeLi(C29H41N2)Cl2(C4H10O2)2], theFeII atom is coordinated by two N and two Cl atoms,generating a distorted FeN2Cl2 tetrahedral geometry. Additionally,one of the chloride atoms bridges to a lithium ion,which is solvated by two dimethoxyethane molecules and iscoordinated in a distorted trigonal-bipyramidal environment.The central Fe, Cl (*2) and Li atoms are coplanar with amaximum deviation of 0.034 A ° .
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Evaluating experimental molecular physics studies of radiation damage in DNA*
PublicationThe field of Atomic and Molecular Physics (AMP) is a mature field exploring the spectroscopy, excitation, ionisation of atoms and molecules in all three phases. Understanding of the spectroscopy and collisional dynamics of AMP has been fundamental to the development and application of quantum mechanics and is applied across a broad range of disparate disciplines including atmospheric sciences, astrochemistry, combustion and environmental...
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Application of spectroscopy to the measurement of blood parameters
PublicationSpectroscopy is the study of formation and interpretation of the spectra arising from the interactions of all types of radiation on matter, understood as a collection of atoms and molecules. This is a very important department of optics which gives us many opportunities to measure various parameters such as material blood parameters. Among the diseases that are associated significantly with changes in rheological properties of...
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A competition between two- and three-body dissociation channels in photo-double-ionization of tetrahydro-2H-pyran and 3,4-dihydro-2H-pyran molecules
PublicationVarious molecules possess structures consisting of the heterocyclic rings containing oxygen atoms. These substances often play a significant role in many different fields of chemistry, medicine, and biology. Due to a specific atomic composition and bond arrangement, many of these molecules retain unique electronic properties, which may be probed by diverse spectroscopic techniques, including those utilizing synchrotron radiation....
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Bis(diethylamido-[kappa]N)(diethylamine-[kappa]N)bis(2,6-diisopropylphenylamido-[kappa]N)zirconium(IV)
PublicationIn the title compound, [Zr(C12H18N)2(C4H10N)2(C4H11N)] or [Zr(HNC6H3iPr2)2(NEt2)2(HNEt2)], which was obtained by the reaction of Zr(NEt)4 with iPr2C6H3NH2, the Zr IV atom is in a trigonal–bipiramidal geometry in which the N atoms from two iPr2C6H3NH and one NEt2 ligand occupy the equatorial positions, and the N atoms of an NEt2 and an Et2NH ligand occupy the apical positions. An intramolecular N—HN contact occurs. There are two...
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Solvothermal synthesis and structural characterization of three polyoxotitanium-organic acid clusters
PublicationThree new titanium oxo-clusters Ti4O2(OiPr)10(OOCPhMe)2 (I), Ti6O4(OEt)8(OOCPhMe)8 (II) and Ti6O6(OEt)6(OOCCHPh2)6 (III) were obtained by easy one-step solvothermal reactions of titanium(IV) isopropoxide, alcohols and carboxylic acids. The three compounds were characterized by single-crystal and powder X-ray diffraction, TGA/DSC, optical and electron microscopy, and FTIR and NMR spectroscopy. X-ray powder diffraction and spectroscopy...
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Modelling charge transfer processes in C2+ -tetrahydrofuran collision for ion-induced radiation damage in DNA building blocks
PublicationInvestigations of collision-induced processes involving carbon ions and molecules of biological interest in particular DNA building blocks, are crucial to model the effect of radiation on cells in order to improve medical treatments for cancer therapy. Using carbon ions appears to be one of the most efficient ways to increase biological effectiveness to damage cancerous cells by irradiating deep-seated tumors. Therefore, interest...
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The accretion of the new ice layer on the surface of hexagonal ice crystal and the influence of the local electric field on this process
PublicationThe process of creation of a new layer of ice on the basal plane and on the prism plane of a hexagonal ice crystal is analyzed. It is demonstrated that the ordering of water molecules in the already existing crystal affects the freezing. On the basal plane, when the orientations of water molecules in the ice block are random, the arrangement of the new layer in a cubic manner is observed more frequently — approximately 1.7 times...
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Electron impact fragmentation of pyrrole molecules studied by fluorescence emission spectroscopy
PublicationThe fluorescence emission spectroscopy using electron impact excitation technique was employed to study fragmentation processes of the gas phase pyrrole molecules. The following excited fragmentation species were observed by detection of their fluorescence decay: the atomic hydrogen H(n), n = 4-7 and the diatomic CH(A2Δ), CN(B2Σ+), NH(A3Π) and C2(d3Πg) fragments. These atomic and molecular products differ from those previously...
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Water-mediated long-range interactions between the internal vibrations of remote proteins
PublicationIt is generally acknowledged that the mobility of protein atoms and the mobility of water molecules in the solvation layer are connected. In this article, we answer the question whether a similar interdependence exists between the motions of atoms of proteins separated by the hydration layers of variable thickness. The system consisted of a kinesin catalytic domain and a tubulin dimer. It was studied using molecular dynamics simulations....
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Superexcited states in the vacuum-ultraviolet photofragmentation of isoxazole molecules
PublicationThe photofragmentation of isoxazole molecules producing excited atomic and molecular fragments has been investigated over the energy range 16-50 eV, using photon-induced fluorescence spectroscopy. The following fragments have been identified by their fluorescence: the excited hydrogen atoms H(n), n = 3-7 and the diatomic CH(A2Δ, B2Σ−), CN(B2Σ+) and C2(d3Πg) fragments. The diatomic fragments are vibrationally and highly rotationally...
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Water-mediated influence of a crowded environment on internal vibrations of a protein molecule
PublicationThe influence of crowding on the protein inner dynamics is examined by putting a single protein molecule close to one or two neighboring protein molecules. The presence of additional molecules influences the amplitudes of protein fluctuations. Also, a weak dynamical coupling of collective velocities of surface atoms of proteins separated by a layer of water is detected. The possible mechanisms of these phenomena are described....
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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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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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Excited states of isoxazole molecules studied by electron energy-loss spectroscopy
PublicationElectron energy-loss spectra were measured in isoxazole in the excitation energy range 3.5−10 eV to investigate the valence excited states. Spectra recorded at different scattering conditions enabled the identification of the singlet and triplet states and the determination of their vertical excitation energies. The two lowest energy triplet bands, ππ* 13A' and ππ* 23A' at 4.20 and 5.30 eV, respectively show vibrational progressions....
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Computational analysis of substituent effects on proton affinity and gas-phase basicity of TEMPO derivatives and their hydrogen bonding interactions with water molecules
PublicationThe study investigates the molecular structure of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives in the gas phase using B3LYP and M06-2X functional methods. Intermolecular interactions are analyzed using natural bond orbital (NBO) and atoms in molecules (AIM) techniques. NO2-substituted TEMPO displays high reactivity, less stability, and softer properties. The study reveals that the stability of TEMPO derivatives...
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Observation of the Hydrogen Migration in the Cation-Induced Fragmentation of the Pyridine Molecules
PublicationThe ability to selectively control chemical reactions related to biology, combustion, and catalysis has recently attracted much attention. In particular, the hydrogen atom relocation may be used to manipulate bond-breaking and new bond-forming processes and may hold promise for far-reaching applications. Thus, the hydrogen atom migration preceding fragmentation of the gas-phase pyridine molecules by the H+, H2+, He+, He2+, and...
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Crystal Structure of N-(2-Benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide
PublicationThe crystal structure of N-(2-benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide indicates that the compound crystallizes in the monoclinic C2/c space group with eight molecules in the unit cell. The heteroatoms from the amide group form a chain of intermolecular N-H ··· O hydrogen bonds propagating along the b axis. The carbonyl group from the benzoyl substituent participates in short contacts with two H-atoms from the ethyl or...
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A Cu/Zn heterometallic complex with solvent-binding cavity, catalytic activity for the oxidation of 1-phenylethanol and unusual magnetic properties
PublicationMononuclear and polymeric complexes of zinc(II) and copper(II) have been synthesized using two isomers of the hemi-salen ligand with a different mutual orientation of donor atoms. The heterometallic Cu/Zn metallocycle features a catalytic niche filled with the molecule of water and molecules of methanol. This unusual compound exhibits both pronounced catalytic activity in the reaction of oxidation of a secondary alcohol to ketone...
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The Ellenbogen's "Matter as Software" Concept for Quantum Computer Implementation: III. Selection of X@C60 Molecular Building Blocks (MBBs) for Tip-Based Nanofabrication (TBN) of Trapped Neutral Atom Quantum Computing Devices
PublicationThe selection of guest atoms X of X@C60 MBBs for TBN of trapped neutral atom quantum computing devices is reported. Assuming the all-optical quantum computing as a final target stage, the two criteria are most important: the charge q accumulated on the C60 host must be as low as possible, and the atom X must have one or more available excited states within the band falling into the low energy window of neutral C60 molecule electronic...
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The Ellenbogen's "Matter as Software" Concept for Quantum Computer Implementation: II Bonding Between the C60 and X@C60 Molecules as Available Molecular Building Blocks (MBBs) for Tip-Based Nanofabrication (TBN) of Quantum Computing Devices
PublicationThe binding energy, BE of the X@C60-X@C60 homodimer and the X@C60-Y@C60 heterodimer resulting from the bond formation between the occupied X@C60 MBB and the C60 molecule was studied by means of semiempirical PM7 calculations, where X and Y denote atoms from H to Bi, excluding Tc and lanthanides. All possible combinations of N = 68 guest atoms were considered, which resulted in K = 2346 of different calculated dimers of (X@C60-Y@C60)...
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Vibrational excitation of acetylene by positron impact
PublicationVibrationally inelastic quantum calculations are carried out at low collision energies for the scattering of a beam of positrons off acetylene gaseous molecules. The normal mode analysis is assumed to be valid and the relative fluxes into the C–C and C–H symmetric vibrational modes are computed within a Body-Fixed (BF) formulation of the dynamics by solving the relevant vibrational Coupled Channels (VCC) equations. The clear dominance...
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Non-ergodic fragmentation upon collision-induced activation of cysteine–water cluster cations
PublicationCysteine–water cluster cations Cys(H2O)3,6 + and Cys(H2O)3,6H+ are assembled in He droplets and probed by tandem mass spectrometry with collision-induced activation. Benchmark experimental data for this biologically important system are complemented with theory to elucidate the details of the collisioninduced activation process. Experimental energy thresholds for successive release of water are compared to water dissociation energies...
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Low-energy positron scattering from gas-phase tetrahydrofuran: A quantum treatment of the dynamics and a comparison with experiments
PublicationIn this paper we report new quantum calculations of the dynamics for low-energy positrons interacting with gaseous molecules of tetrahydrofuran. The new quantum scattering cross sections are differential and integral cross sections at collision energies between 1.0 and 25.0 eV and include a careful treatment of the additional effects on the scattering process brought about by the permanent dipole moment of the target molecule....
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Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands
PublicationFive nickel(II) complexes containing aliphatic diamines and tri-tert-butoxysilanethiolate ligand have been synthesized for the purpose of studying their structural, spectral (IR, UV–Vis, HF EPR) and thermal properties. Complexes (1)–(5) have been prepared in high yield by reactions of [Ni{SSi(OtBu)3}2(NH3)(H2O)] with 1.3-propanediamine (L1), 1,6-hexanediamine (L2), or 1,7-heptanediamine (L3). The X-ray structures were determined...
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Low-energy interactions related to atmospheric and extreme conditions
PublicationThis Topical Issue, entitled “Low-Energy Interactions Related to Atmospheric and Extreme Conditions”, showcases a collection of eighteen articles that reported recent theoretical and experimental findings pertaining to the following topics: – low-energy interactions of charged particles (electrons [1–7], protons [8], positrons [9]), and photons [10] with atoms and molecules of biological [1–4,7,8], astrochemical [10], industrial,...
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The importance of the shape of the protein-water interface of a kinesin motor domain for dynamics of the surface atoms of the protein
PublicationSingle kinesin motor domain immersed in water has been investigated using molecular dynamics. It has been found that local properties of water in solvation shell change along with the nature of neighboring protein surface. However, a detailed analysis leads to the conclusion that the geometrical features of hydrogen bonds and overall structure of kinesin hydration water is not very different from bulk water. The local values of...
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The importance of the shape of the protein–water interface of a kinesin motor domain for dynamics of the surface atoms of the protein
PublicationA single kinesin motor domain immersed in water has been investigated using molecular dynamics. It has been found that local properties of water in the solvation shell change along with the nature of the neighboring protein surface. However, a detailed analysis leads to the conclusion that the geometrical features of hydrogen bonds and overall structure of kinesin hydration water are not very different from bulk water. The local...
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Self-assembly of secondary aryl amides in cocrystals with perfluoroaryl coformers: structural analysis and synthon preferences
PublicationCooperation of aryl⋯perfluoroaryl stacking interactions and hydrogen bonds was utilized in the construction of six novel cocrystals of aromatic cis-amides with pentafluorobenzoic acid (pfba) and pentafluorophenol (pfp). They were obtained by crystallization from solution and structurally characterized. In four instances, the components form heterotetrameric motifs, in which amide:amide homodimer interacts symmetrically on two sides...