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Laboratory studies of reactions of O+ and N+ ions with molecular hydrogen and its isotopologues, HD and D2, at low temperatures
Kovalenko, Artem ; Glosík, Juraj (advisor) ; Jusko, Pavol (referee) ; Poterya, Viktoriya (referee)
This work is focused on the laboratory studies of reactions of O+ and N+ ions with molecular hydrogen and its isotopologues, HD (hydrogen deuteride) and D2. The experimental studies were performed using a 22-pole radiofrequency ion trap in the temperature range from 15 K to 300 K. The temperature dependencies of measured reaction rate coefficients are presented for all reactions. Studied reactions are important for astrochemistry. The reaction of O+ with H2 initiates a water production sequence in the interstellar medium, and the rate coefficient does not change dramatically with temperatures in the covered range. The measured rate coefficients for reactions of O+ with H2, HD, and D2 are close to the corresponding Langevin rate coefficients. The reaction of O+ with HD has two reaction channels with products, OH+ and OD+. The ratio of rate coefficient of the OH+ production channel to the total reaction rate coefficient is close to 0.5 in the studied temperature range. The reaction of N+ with H2 initiates the ammonia production sequence in the interstellar medium. This reaction has activation energy on the order of a few meV, which is significant in the conditions of the interstellar medium. For reactions of N+ with H2 and its isotopologues, activation energies were determined from measured...
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Experimental study of the dissociative recombination of molecular ions at temperatures relevant to cold interstellar plasma (30 - 300 K)
Shapko, Dmytro ; Glosík, Juraj (advisor) ; Korolov, Ihor (referee) ; Poterya, Viktoriya (referee)
TITLE: Experimental Study of the Dissociative Recombination of Molecular Ions at Temperatures Relevant to Cold Interstellar Plasma (30 - 300 K) AUTHOR: Mgr. Dmytro Shapko DEPARTMENT: Department of Surface and Plasma Science SUPERVISOR: prof. RNDr. Juraj Glosík, DrSc. ABSTRACT: The dissociative recombination process of N2H+ ions with electrons was investigated using a stationary afterglow combined with a Cavity Ring-Down Spectrometer. We conducted real-time observations of the changes over time in the population densities of various rotational and vibrational states of recombining N2H+ ions. Based on these observations, we determined the rate coefficients for thermal recombination of N2H+ within a temperature range of 80 - 350 K. By employing newly calculated vibrational transition moments of N2H+ , we provided an explanation for the discrepancies observed in previous studies regarding the recombination rate coefficients. Furthermore, our findings indicate that the measured recombination rate coefficient does not exhibit a statistically significant correlation with the number density of the buffer gas. We also conducted a study on the dissociative recombination of H3 + ions with electrons in neon gas at a temperature of 110 K. To perform this investigation, we utilized a new Cryogenic Stationary...
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Studies of reactions of ions with water molecules in the gaseous phase for trace gas analysis
Lacko, Michal ; Španěl, Patrik (advisor) ; Milosavljevič, Aleksandar (referee) ; Poterya, Viktoriya (referee)
Chemical ionization mass spectrometry (CI-MS) is a powerful analytical technique, capable to detect trace levels of organic molecules diluted in air samples in real-time. Processes leading to ionization of organic molecules, necessary for their detection and identification, are however often strongly affected by the presence of water vapours in form of sample humidity. In the present work, I studied the influence of water vapours on ion chemistry and, subsequently, the respective influence on sensitivity and selectivity of CI-MS techniques. Studies were carried out using several soft chemical ionization mass spectrometry instruments, including Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Proton Transfer Reaction Mass Spectrometry (PTR-MS) and Selected Ion Flow-Drift Tube Mass Spectrometry (SIFDT-MS). Experimental studies were also supplemented by theoretical simulation of proposed ion chemistry using the Kinetic of Ion-Molecular Interaction simulator (KIMI), developed by the author. In this thesis, I present a study of formaldehyde, glyoxal and phthalates ion chemistry with H3O+ , NO+ and O2 + reagent ions, focusing on secondary reactions with water vapours. Additionally, I also studied secondary reactions of protonated hydrated acetic acid with acetone. Finally, I have carried out...
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Investigation of external stimuli-influenced temperature-sensitive polymers behavior studied by spectroscopic methods
Velychkivska, Nadiia ; Starovoytova, Larisa (advisor) ; Lang, Jan (referee) ; Poterya, Viktoriya (referee)
Temperature-sensitive polymers or "smart" polymers are materials that undergo phase separation initiated by temperature change. Some of these polymers possess phase separation temperatures close to human body temperature (37 C), thus offering a wide range of potential applications in controlled drug release or gene delivery systems, bioseparations, tissue engineering, etc. Of the polymers with a phase separation temperature close to 37 C, poly(N- isopropylacrylamide) (PNIPAM) and poly(vinyl methyl ether) (PVME) are perhaps the most important and were selected as the subjects of this study. In this work, these two polymers have been examined in the presence of low molecular weight additives, and their colloidal stability evaluated using 1 H NMR (nuclear magnetic resonance) and time-resolved 1 H NMR spin-spin relaxation time T2 experiments. An improved model of the two exchangeable states was applied for a more detailed characterization of the phase separation process. The main focus of this study was to determine the influence of additives on the phase separation behavior of the polymers (phase separation temperature, width of transition, maximum number of polymer chains participating in phase separation), reversibility of the phase separation, dynamics of solvent molecules (water and additive),...
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Ion trap
Hejduk, Michal ; Glosík, Juraj (advisor) ; Poterya, Viktoriya (referee)
In the thesis, elementary problems observable in a temperature variable linear multipole trap are described. Those elementary processes that are important for low-temperature interstellar plasma are briefly summarized in the first part. In the same chapter, a theory about particles-confinement in a Paul trap is shortly explained as well. In the second part of the work, the Atomic Beam 22-Pole Trap experimental apparatus from the Physical Institute of the Nature Science Faculty of the Technical University in Chemnitz is described. In the last section, first measurements using the mentioned apparatus are described and interpreted.
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Solvent Influence on Photochemistry of Small Biomolecules in Clusters
Profant, V. ; Dian, J. ; Fárník, Michal ; Poterya, Viktoriya
We present a photolysis study of pyrrole, imidazole and pyrazole clusters in comparison to the photolysis of the isolated molecules. Size distributions of different mean cluster sizes have been prepared and characterized in supersonic expansions. The clusters were photolyzed at 243 and 193 nm and the kinetic energy distributions (KEDs) of the H-fragments were measured. The KEDs of all systems exhibit a bimodal character with slow and fast H-fragment peaks similar to the spectra of the corresponding single molecules. However, with the increasing clusters size the slow component gains on intensity in comparison to the fast component. A similar effect is observed with increasing the excitation energy from 243 to 193 nm.
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