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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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Reactions of astrophysically important positive ions with molecules and atoms at low temperatures
Rednyk, Serhiy ; Glosík, Juraj (advisor)
4 Title: Reactions of astrophysically important positive ions with molecules and atoms at low temperatures Author: Serhiy Rednyk Department: Department of Surface and Plasma Science Supervisor of the doctoral thesis: prof. RNDr. Juraj Glosík, DrSc, Ph.D., Department of Surface and Plasma Science Abstract: In the present work, the results of the experimental study of reactions of ions with atomic and molecular hydrogen are presented. Experiments were performed using a cold radiofrequency 22-pole ion trap apparatus in the temperature range, relevant for interstellar clouds (from 300 down to 15 K). The present study is devoted to experimental investigation of the reactions of NH+, NH2 + and NH3 + ions with H2. The reaction of NH+ with H2 has two channels, which lead to NH2 + (about 97 %) and H3 + (3 %) formation with nearly constant reaction rate coefficients. The reaction of NH2 + + H2 produces only NH3 + ions and the measured reaction rate coefficient is decreasing with increasing temperature from 6∙10−10 cm3 s−1 to 2∙10−10 cm3 s−1 . The measured reaction rate coefficient of NH3 + with H2, producing NH4 +, is increasing with decreasing temperature from 80 K down to 15 K, confirming predicted mechanism of tunneling through a potential barrier. Reaction of NH+ + H was studied using a combination of the 22-pole...
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Study of state selected interactions of ions with molecular hydrogen at temperatures relevant to astrochemistry
Zymak, Illia ; Glosík, Juraj (advisor) ; Bánó, Gregor (referee) ; Španěl, Patrik (referee)
In this work are presented results of the experimental study of state selected reactions of H+ and N+(3PJa) ions with molecular hydrogen H2(J = 0, 1) at temperatures in the range 10 - 100 K using 22-pole rf ion trap apparatus. These reactions are important for the formation of interstellar trihydrogen cations and ammonia. To determine the temperature of ions, calibration measurements of the Doppler broadening of spectral lines using N2+ + Ar Ar+ + N2 laser induced reaction and rate of the ternary association He+ + 2He He2+ + He were performed. Both ternary and radiative channels of the H+ + H2(J) association reaction were observed at hydrogen number densities in the range 1012 - 1014 cm-3 and 1011 - 1012 cm-3 respectively. Obtained temperature dependences at 11 - 33 K demonstrate substantial role of the H2 rotational energy, results cannot be explained with the existed theories of the stabilization of collisional complexes. Measurements of the rate coefficient of N+(3PJa) + H2(J) reaction at different ortho fractions of H2 show dependence on internal energy of both reactants. State specific rate coefficients of the reaction of nitrogen and hydrogen ions were derived. The adiabatic model and collisional relaxations of N+(3PJa) fine structure levels were considered. Powered by TCPDF (www.tcpdf.org)
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Radicals formation in supersonic plasma jet
Mašát, Milan ; Tichý, Milan (advisor) ; Glosík, Juraj (referee)
Title: Creation of radicals in electric discharge supersonic plasma jet Author: Milan MaSat Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Milan Tichy, DrSc. Supervisor's e-mail address: Milan.Tichy@mff.cuni.cz Abstract: Free radicals are the key intermediates and propagators of chemical reactions in Earth's atmosphere. Study of their structure and chemical properties is vital for understanding the processes in atmosphere. But their high reactivity brings the need for specific research methods. In-situ preparation and non-invasive detection and characterization techniques are needed. Most commonly used laboratory techniques such as photodissociation or electric discharge generate radicals at temperatures that are significantly higher then those under atmospheric conditions, which we intendto model. In this work, I was developing a source of cold radicals and experimental techniques for measuring their properties. 1 combined plasma source, which creates sufficient concentrations of radicals with supersonic expansion in which the translational and internal degrees of freedom are cooled deeply below the room temperature. For their characterization I used high-resolution spectroscopy utilizing near infrared laser diodes. I also developed and built electronic circuits and software...
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Implementation of ion imaging technique in experiments with free molecules, clusters and nanoparticles
Kočišek, Jaroslav ; Fárník, Michal (advisor) ; Klán, Petr (referee) ; Glosík, Juraj (referee)
Title: Implementation of ion imaging technique in experiments with free molecules, clusters and nanoparticles Author: Jaroslav Kočišek Department: Department of Surface and Plasma Science Supervisor: Mgr. Michal Fárník, PhD., DSc., Ústav fyzikální chemie J. Hey- rovského, AV ČR, v.v.i. Abstract: The experimental work is focused on implementation of novel tech- niques to study clusters and nanoparticles in molecular beams. A new exper- imental system was tested, which combines the technique of velocity map ion imaging with pulsed molecular beam source. The same method and new mass spectrometer were implemented on the apparatus with molecular beam of size selected clusters. The new methods were used to study environmental effects on photo and electron induced chemistry. The most important results concerns on influence of expansion conditions on the structure of formed neutral clusters of HBr and C2H2. Results of experiments with HNO3 and CF2Cl2 molecules are then crucial for understanding heterogeneous processes in the Stratosphere. Keywords: ion imaging, mass spectrometry, molecular beams, photochemistry, nanoparticles
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Rekombinace a reakce iontů v plazmatu
Varju, Jozef ; Glosík, Juraj (advisor) ; Kaňka, Adolf (referee)
One of the most interesting questions in contemporary interstellar chemistry is the HCN/HNC abundance ratio observed in dense interstellar clouds. The observed ratios vary from 80:1 to 1:5 depending on the object under observation. These ratios represent a striking deviation from thermochemical equilibrium. Dissociative recombination of HCNH+ has been invoked to explain these observations. It is suggested to study details of this recombination using FALP apparatus equipped with NIR Cavity Ringdown Absorption Spectrometer (IR - CRDS). In the presented work we have developed kinetic model describing formation of HCNH+/e- plasma and consequent production of HCN and HNC. Analysed and discussed are conditions of experiment and applicability of IR - CRDS for the proposed study. To confirm our analyses the preliminary experiments were carried out using microwave discharge cell equipped with IR - CRDS. Studies of H3O+ and H2D+ ions were carried out to put together the experiment. The absorption spectra in a plasma containing He/N2/CH4 were measured in order to determine transition frequencies for study of products of recombination of CNH+ ions.
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