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Wyniki wyszukiwania dla: PROTON TRANSFER REACTION MASS SPECTROMETRY
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High-Throughput Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry as an Alternative Approach to Monitoring Drug Resistance of Hepatitis B Virus
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A new silylating reagent – dimethyl(3,3,3-trifluoropropyl)silyldiethylamine – for the derivatisation of non-steroidal anti-inflammatory drugs prior to gas chromatography–mass spectrometry analysis
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Determination of bromhexine and its metabolites in equine serum samples by liquid chromatography – Tandem mass spectrometry: Applicability to the elimination study after single oral dose
PublikacjaBromhexine (BH), expectorant used in the treatment of respiratory disorders associated with viscid or excessive mucus, is not permitted for use in the competing horse by many authorities in horseracing and Olympic disciplines. Metabolic studies are of the great importance in anti-doping field because they allow for updating the selection of the most appropriate markers for prohibited substances, such as metabolites present at higher...
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Dispersive solid-phase extraction using multi-walled carbon nanotubes combined with liquid chromatography–mass spectrometry for the analysis of β-blockers: Experimental and theoretical studies
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Determination of parent and methylated polycyclic aromatic hydrocarbons in water samples by dispersive liquid–liquid microextraction–two dimensional gas chromatography–time-of-flight mass spectrometry
PublikacjaPolycyclic aromatic hydrocarbons (PAHs) are contaminants frequently found in environmental waters. Owing to their toxic effects, it is important to develop analytical methodologies that allow their fast and reliable determination. Dispersive liquid–liquid microextraction (DLLME) allows a quick extraction of analytes with little organic solvent consumption. The best results regarding sample preparation are obtained when 40 mL of...
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Experimental study of flow boiling pressure drop and heat transfer of R1233zd(E) at moderate and high saturation temperatures
PublikacjaThe paper presents the results of experimental study of flow boiling of R1233zd(E) in minichannel at moderate and high saturation temperatures. The heat transfer coefficient and pressure drop were measured for flow boiling in a stainless steel tube with 2 mm inside diameter and a length of 300 mm. Experiment has been conducted for saturation temperatures ranging from 83 to 145 °C which corresponds to values of reduced pressures...
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Application of headspace-solid phase microextraction followed by gas chromatography-mass spectrometry to determine short-chain monocarboxylic acids in cattle farm wastewater and waste landfill leachates
PublikacjaZaproponowano metodykę oznaczania krótkołańcuchowych kwasów monokarboksylowych w ściekach z hodowli bydła i odciekach ze składowisk zawierających organiczne odpady, oparta na technice mikroekstrakcji do fazy stacjonarnej z fazy nadpowierzchniowej próbek ciekłych, w połączeniu ze sprzężonym układem GC-MS.
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Determination of tributyltin (TBT) in marine sediment using pressurised liquid extraction–gas chromatography–isotope dilution mass spectrometry (PLE–GC–IDMS) with a hexane–tropolone mixture
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Determination of tributylotin (TBT) in marine sediment using pressurised liquid extraction-gas chromatography-isotope dilution mass spectrometry (PLE-GC-IDMS) with a hexane-tropolone mixture
PublikacjaOpracowano metodę oznaczania zawartości tributylocyny w próbkach osadu morskiego. Na etapie izolacji zastosowano technikę przyspieszonej ekstrakcji za pomocą roztworu tropolonu w heksanie.Na etapie oznaczeń końcowych wykorzystano technikę chromatografii gazowej, stosując metodę spektrometrii mas rozcieńczenia izotopowego. Wyznaczono parametry walidacyjne opracowanej metody: granicę wykrywalności, precyzję, poprawność i niepewność.
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Simultaneous analysis of non-steroidal anti-inflammatory drugs and estrogenic hormones in water and wastewater samples using gas chromatography–mass spectrometry and gas chromatography with electron capture detection
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Application of gas flow headspace liquid phase micro extraction coupled with gas chromatography-mass spectrometry for determination of 4-methylimidazole in food samples employing experimental design optimization
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Experimental study and comparison with predictive methods for flow boiling heat transfer coefficient of HFE7000
PublikacjaThis article describes an experimental study of flow boiling of HFE7000 inside a smooth vertical channel. The investigation has been carried out in a circular stainless-steel tube with an inner diameter of 2.3 mm. The data have been collected for the applied heat fluxes q ranging from 61 to 205 kW/m2, the mass flux G ranging from 214 to 1006 kg/(m2 s), the saturation temperature Tsat ranging from 30 to 54 °C and the full range...
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Electron impact iozization of CCl4 and SF6 embedded in superfluid helium droplets
PublikacjaElectron 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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Application of gas chromatography,mass spectrometry and olfactometry for quality assessment of selected food products = Zastosowanie chromatografii gazowej, spektrometrii mas i olfaktometrii w ocenie jakości wybranych produktów spożywczych
PublikacjaStosując mikroekstrakcję do fazy stacjonarnej z fazy nadpowierzchniowej jako metodę przygotowania próbek i chromatografię gazową (GC) ze spektrometrią mas (MS) i olfaktometrią (O) jako metodę oznaczeń końcowych oznaczono lotne związki w spirytusach i miodach. Identyfikację przeprowadzono przez porównanie widm masowych z widmami z biblioteki NIST. Dodatkowo, wykrywane przez panel oceniający związki zapachowe rejestrowano w formie...
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Vacuum ultraviolet photoionization and ionic fragmentation of the isoxazole molecules
PublikacjaThe photofragmentation of the isoxazole molecules producing ionized atomic and molecular fragments was investigated in the photon energy range of 9e32 eV, using synchrotron radiation excitation combined with ion time-of-flight spectrometry. Twenty-one well resolved cations were identified in the mass spectra of the isoxazole, and their appearance energies were determined. The yield curves of these cations were obtained in the photon...
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Toward Mechanosynthesis of diamondoid structures: III. Quantum-chemical study of silylene molecule and silicon atom transfer mechanism from caped SWCNT tip to the reaction center on a hydrogenated Si(111) surface
PublikacjaOpublikowana wcześniej (Modelling Simul. Mater. Sci. Eng., Vol. 7, 1999, pp. 43-58) strategia mechanosyntezy struktur krzemu na uwodornionej płaszczyźnie Si(111) została poszerzona poprzez uwzględnienie ostrza w postaci zamkniętej SWCNT jako urządzenia kontrolującego położenie cząsteczki sililenu oraz atomu krzemu.
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Accurate, Direct, and High-Throughput Analyses of a Broad Spectrum of Endogenously Generated DNA Base Modifications with Isotope-Dilution Two-Dimensional Ultraperformance Liquid Chromatography with Tandem Mass Spectrometry: Possible Clinical Implication
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“Dilute & Shoot” approach for rapid determination of trace amounts of nicotine in zero-level e-liquids by reversed phase liquid chromatography and hydrophilic interactions liquid chromatography coupled with tandem mass spectrometry-electrospray ionization
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Theoretical consideration of free convective heat transfer from a round isothermal plate slightly inclined from the vertical
PublikacjaA semi-analytical solution of simplified Navier-Stokes and Fourier-Kirchhoff equations describing free convective heat transfer from a round isothermal surface slightly inclined from the vertical is presented. The solution is based on the assumption, typical for natural convection, that the velocity component normal to the surface is negligibly small in comparison to the tangential one. Next we neglect the nonlinear inertia force...
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Natural convective heat transfer from isothermalconic
PublikacjaTheoretical considerations on convective heat transfer from isothermal upward conicalsurfaces have been presented. The physical model of this phenomenon consists of an isothermalcone of inclination angle (φ) between the cone generating line (X) and the radius (R) of the cone base. The angle is a parameter of conical surface which varied from (φ = 0−circular horizontal plate) to (φ = π/2—vertical cylinder) . Onthe basis of Navier–Stokes...
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CO2 capture through direct-contact condensation in a spray ejector condenser and T- junction separator
PublikacjaThe design principle underlying the steam condensation and CO2 purification in a gas power plant with a focus on reducing CO2 emissions encompasses the deployment of a spray ejector condenser (SEC) and separator. This innovative system facilitates direct-contact condensation of steam with non-condensable gas (CO2) by inter acting with a spray of subcooled water, seamlessly integrated with a T-junction separator mechanism aimed...
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Numerical model for thin liquid film with evaporation and condensation on solid surfaces in systems with conjugated heat transfer
PublikacjaCondensation and evaporation processes from wetted surfaces are of utmost importance in many technological or industrial applications. In many devices such as home-appliances and air conditioning systems just to name a few, condensation and evaporation processes greatly impact their performance and energy efficiency; The physics of these processes is quite complex, involving conjugate heat transfer among solid–liquid film-gaseous...
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Synergistic effects of nitrogen-doped carbon and praseodymium oxide in electrochemical water splitting
PublikacjaHybrid materials featuring perovskite-type metal oxide in conjunction with heteroatom-doped graphene hold immense promise as alternatives to costly noble metal catalysts for electrochemical water splitting, facilitating the generation of environmentally friendly hydrogen. In this study, perovskite-type oxide containing praseodymium, barium, strontium, cobalt, and iron atoms dispersed in a carbon matrix as a catalyst is synthesized...
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Analiza oddziaływań w kryształach związków zawierających w strukturze pierścień pirydynowy
PublikacjaMożliwość tworzenia się wiązań wodorowych jest kluczowym parametrem z punktu widzenia inżynierii kryształu, ponieważ wiązania wodorowe mają bezpośredni wpływ na strukturę oraz trwałość sieci krystalicznej. Głównym celem niniejszej rozprawy doktorskiej była analiza porównawcza wiązań wodorowych występujących w układach, zawierających w strukturze pierścień pirydynowy. Badane układy podzielono na: (1) układy ze związkami krzemosiarkowymi...
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Release Kinetics Studies of Early-Stage Volatile Secondary Oxidation Products of Rapeseed Oil Emitted during the Deep-Frying Process
PublikacjaThe research concerns the use of proton transfer reaction mass spectrometer to track real-time emissions of volatile secondary oxidation products released from rapeseed oil as a result of deep-frying of potato cubes. Therefore, it was possible to observe a sudden increase of volatile organic compound (VOC) emissions caused by immersion of the food, accompanied by a sudden release of steam from a potato cube and a decrease of the...
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Dissociative electron attachment and anion-induced dimerization in pyruvic acid
PublikacjaWe 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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Surprising Radiolytic Stability of 8‑Thiomethyladenine in an Aqueous Solution
Publikacja8-Thiomethyladenine (ASCH3), a potentially radiosensitizing modified nucleobase, has been synthesized in a reaction between 8-thioadenine and methyl iodide. Despite favorable dissociative electron attachment (DEA) characteristics, the radiolysis of an aqueous solution of ASCH3 with a dose of X-ray amounting to as much as 300 Gy leads to no effects. Nevertheless, crossed electron-molecule beam experiments in the gas phase on ASCH3...
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Imidazolium silanethiolates relevant to the active site of cysteineproteases. A cooperative effect in a chain of NH(+)...S(-) hydrogenbonds
PublikacjaThree imidazolium silanethiolates relevant to the active site of cysteine proteases have been synthesized and investigated by X-ray diffraction, IR spectroscopy and computational methods. As indicated by crystallographic and FT-IR data in the solid state, the transfer of proton from thiol to imidazole takes place and a thiolato-imidazolium ion pair is formed. The FT-IR spectra of crystalline imidazolium silanethiolates exhibit...
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Recent Applications of 1D GC-MS and 2D GC-MS in Foodomics Studies
PublikacjaGas chromatography coupled with mass spectrometry and food chemistry have been tightly linked since the 1960s. This setup is also an integral part of the omics studies when it comes to low mass metabolites. Therefore, the marriage of GC-MS and foodomics is obvious. Two-dimensional gas chromatography coupled with mass spectrometry fits perfectly within the latest trends in foodomics, since it is tailored for holistic food analysis....
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Charge-assisted N(+)–H···(−)S hydrogen bonds in the crystal structure of selected diammonium thiophenolates.
PublikacjaNew salts of thiophenol with three flexible aliphatic diamines H2N(CH2)nNH2 (n = 2, 4 and 6) have been synthesized and characterized by elemental analyses, IR spectroscopy and X-ray crystallography in order to analyze their supramolecular architecture. Structural analyses indicate that in the crystals, proton transfer has occurred, with the –SH group giving (+)N–H···S(−) hydrogen bonding interaction. The structure of compound 1...
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UV-induced electron transfer between triethylamine and 5-bromo-2′-deoxyuridine. A puzzle concerning the photochemical debromination of labeled DNA
Publikacja5-Bromo-2'-deoxyuridine (BrdU) photosensitizes DNA to strand break formation. However, this type of photodamage is completely quenched by the presence of triethylamine (TEA) which originates from RP-HPLC purification commonly employed by oligonucleotide providers. While the presence of TEA in oligonucleotide samples does not interfere with PCR or other molecular biology applications, the mechanism of photochemical reaction proceeding...
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Nowe substancje psychoaktywne Cz. III. Syntetyczne katynony-charakterystyka, metody oznaczania i wyzwania analitycznje
PublikacjaSyntetyczne katynony to druga co do liczebności (po syntetycznych kannabinoidach) grupa nowych substancji psychoaktywnych będących składnikiem dopalaczy zabezpieczanych przez policję w nielegalnym handlu. Substancje te po raz pierwszy wykryto w Europie w 2004 r., a do końca roku 2015 zidentyfikowano aż 103 nowe związki z tej grupy. Możliwość wprowadzania dodatkowych grup funkcyjnych w strukturę katynonu pozwala na niezwykle wiele...
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Monitoring of volatile organic compounds (VOCs) in atmospheric air. Part I. On-line gas analyzers
PublikacjaThe paper reviews the subject literature concerning the analytical instruments routinely used for monitoring volatile organic compounds in atmospheric air. The analyzers are classified as stationary or mobile according to their ease of transport. Stationary DOAS (Differential Optical Absorption Spectroscopy) analyzer is characterized, as are MIMS (Membrane Introduction Mass Spectrometry), MESI (Membrane Extraction with Sorbent...
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Funcionality assessment of Citrus Hysteria peel as a protective barrier using gas chromatography
PublikacjaThe aim of this study was to analyse the volatile fractions of fruit peel and pulp using two-dimensional gas chromatography technique coupled with mass spectrometry. The isolation of the compounds was achieved by microextraction to the stationary phase from the headspace of the sample (HS-SPME). Mass spectrometry with time-of-flight analyser (TOF-MS) was used to identify the chemical compounds. There are no reports in the literature...
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Electrochemical simulation of metabolism for antitumor-active imidazoacridinone C-1311 and in silico prediction of drug metabolic reactions
PublikacjaThe metabolism of antitumor-active 5-diethylaminoethylamino-8-hydroxyimidazoacridinone (C-1311) has been investigated widely over the last decade but some aspects of molecular mechanisms of its metabolic transformation are still not explained. In the current work, we have reported a direct and rapid analytical tool for better prediction of C-1311 metabolism which is based on electrochemistry (EC) coupled on-line with electrospray...
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Comprehensive two-dimensional gas chromatography and three-dimensional fluorometry for detection of volatile and bioactive substances in some berries
PublikacjaThe volatilefractionsofCapegooseberryandblueberryweredeterminedbyheadspacesolid-phase microextractioncoupledwithcomprehensivetwo-dimensionalgaschromatographywithtime-of-flight mass spectrometry(HS-SPME/GCGC-TOFMS).Thehighestamountofalcohol(51.8%),ester(32.8%)and carboxylicacid(6.9%)wasinblueberryincomparisonwithgooseberryandoppositelyketones(14.7%), aldehydes(9.9%)andterpenes(8%)werefoundingooseberry.Thebioactivecompoundsandantioxidant capacities...
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The Role of Electron Transfer in the Fragmentation of Phenyl and Cyclohexyl Boronic Acids
PublikacjaIn this study, novel measurements of negative ion formation in neutral potassium-neutral boronic acid collisions are reported in electron transfer experiments. The fragmentation pattern of phenylboronic acid is comprehensively investigated for a wide range of collision energies, i.e., from 10 to 1000 eV in the laboratory frame, allowing some of the most relevant dissociation channels to be probed. These studies were performed in...
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Ionization and ionic fragmentation of tetrahydrofuran molecules by electron collisions
PublikacjaElectron 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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Water uptake and energetics of the formation of barium zirconate based multicomponent oxides
PublikacjaA group of multi-component oxides based on BaZrO3 have been prepared using a solid-state reaction method and examined in terms of their water uptake and thermodynamics of formation. Depending on the type and amount of acceptor substitution, the synthesized compounds exhibit various proton defect concentrations, reaching up to 0.2 mol/mol for a compound containing 10 different elements in the B-sublattice, where 50% of them are...
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Electron ionization induced fragmentation of fluorinated derivatives of bisphenols
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Chemistry induced by low-energy electrons in condensed multilayers of pure small organic acids
PublikacjaPrzedstawiono reakcje indukowane przez niskoenergetyczne elektrony (0.7 - 20 eV) w kondensowanych warstwach kwasu mrówkowego (HCOOH), częściowo deuterowanego kwasu octowego (CH3COOD) oraz kwasu trifluorooctowego (CF3COOD).
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Dissociation and fragmentation of furan by electron impact
PublikacjaDissociation and fragmentation processes that produce electronically excited atomic and molecular fragments, following electron impact excitation, have been studied in furan. The optical excitation technique has been employed over the electron incident energy range 15-95 eV. Formation of excited hydrogen atoms H(n) in the n = 4-10 states has been detected by observation of the Balmer series. The diatomic CH fragments are formed...
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Electron impact ionization of CCl4 and SF6 embedded in superfluid helium droplets
PublikacjaBadana była jonizacja helowych nano-kropel o rozmiarach 104 z osadzonymi wewnątrz molekułami CCl4 i SF6. Zmierzone z dużą rozdzielczością widma masowe wskazują na tworzenie dużych klasterów w przypadku CCl4. Zależność intensywności jonizacji w funkcji energii wskazuje, że w przypadku obu molekuł osadzają się one wewnątrz kropli. Zaobserwowano jon macierzysty CCl4-, prawdopodobnie powstający na drodze jonizacji Penninga podczas...
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Bi-dipole-bound anions
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Possible mechanisms for protecting NCα bonds in helical peptides from electron-capture (or transfer) dissociation
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Reactions in nanofilms of trifluoroacetic acid (CF3COOH) driven by low energy electrons
PublikacjaBadano modyfikacje chemiczne indukowane przez niskoenergetyczne elektrony (0-20eV) w cienkich warstwach skondensowanych molekuł CF3COOH. Do badań zastosowano dwie metody: desorpcję jonów w wyniku bombardowania elektronami (ESD - Electron Stimulated Desorption) oraz termiczną desorpcję jonów (TDS - Thermal Desorption Spectroscopy).
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Electron-impact ionization of fluoromethanes – Review of experiments and binary-encounter models
PublikacjaExperiments and recommended data on electron-impact ionization of methane and fluoromethanes (CH3F, CH2F2, CHF3, CF4) are reviewed and compared with binary-encounter models (Gryzinski’s, ´ Deutsch and Märk’s, and Kim and Rudd’s). A good agreement between recent experiments and the two latter classical-like models is shown. Kim and Rudd’s model (calculated presently in the restricted HartreeFock 6-31**G orbital basis) predicts well...
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Ionization of tocopherols and tocotrienols in atmospheric pressure chemical ionization
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Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes
PublikacjaRecent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C3H4N2O+ (uracil+ less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine...
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Low energy electron attachment to platinum(II) bromide (PtBr2)
PublikacjatDissociative electron attachment to PtBr2in the gas phase was studied in the low electron energy rangefrom zero up to 10 eV with an energy resolution of 150 meV. The experiments were carried out using ahemispherical electron monochromator coupled with a quadrupole mass spectrometer and pulse count-ing acquisition system. The only anion observed was Br−. This ion is formed at three resonance electronenergies: 0.4 eV, 1.2 eV and...