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Elementary Processes at Low Temperatures - Reactions of H3+ and N2H+ in Afterglow Plasmas
Kálosi, Ábel ; Plašil, Radek (advisor) ; Rubovič, Peter (referee) ; Španěl, Patrik (referee)
Electron-ion recombination and ion-neutral interactions play a piv- otal role in the chemical evolution of molecules in the Interstellar Medium (ISM). Physical conditions under which these processes un- dergo in the ISM include a wide range of temperatures and particle number densities. This work contributes to the experimental study of named low temperature phenomena in the range of 30 K to 300 K focusing on the reactions of hydrogen-containing light molecules. The employed experimental techniques are based on a combination of a Stationary Afterglow (SA) instrument with a Continuous Wave Cavity Ring-down Spectrometer (cw-CRDS). The main contributions of this work can be split into three topics. (1) The proton and deuteron con- taining isotopic system of H3 + ions. The isotopic fractionation process in collisions with hydrogen and deuterium gas was investigated in low temperature discharges, nominal ion temperatures of 80 K to 140 K, to deduce relative ion densities in the experiments. These are necessary for afterglow studies of isotopic effects in electron-ion recombination of the studied ions. (2) Vibrational spectroscopy of N2H+ ions focusing on first overtone (2ν1 band) transitions and ion thermometry, the first step towards studies of electron-ion recombination. (3) The role of para/ortho spin...
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A model of resonant collisions of electrons with molecules and molecular ions
Váňa, Martin ; Houfek, Karel (advisor) ; Cejnar, Pavel (referee) ; Mašín, Zdeněk (referee)
A two-dimensional model of the resonant electron-molecule collision processes with one nuclear and one electronic degree of freedom introduced by Houfek, Rescigno and McCurdy [Phys. Rev. A 73, 032721 (2006)] and a similar two- dimensional model of the dissociative recombination with potential proposed by Hamilton [Ph.D. thesis, University of Colorado, (2003)] are formulated within the time-dependent framework and solved numerically using the finite-element method with the discrete variable representation basis, the exterior complex scaling method and the generalized Crank-Nicolson method. On the model of electron-molecule collisions we illustrate how the time-dependent calculations can provide a deep insight into the origin of oscillatory structures in the vibrational excitation cross sections if one evaluates the cross sections not only at sufficiently large time to obtain the final cross sections, but rather at several characteristic times which are given by the evolution of the system. With use of the time- dependent calculations we demonstrate the complex nature of the dissociative recombination model dynamics and we propose the interpretation of the recom- bination process mechanism. We also propose few techniques for the explanation of the sharp structures in the dissociative recombination cross sections...
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Recombination of ions in plasma at 50-300 K
Rubovič, Peter ; Glosík, Juraj (advisor) ; Fárník, Michal (referee) ; Korolov, Ihor (referee)
A B S T R A C T Title: Recombination of Ions in Plasma at 50 − 300 K Author: Peter Rubovič Supervisor: Prof. RNDr. Juraj Glosík, DrSc. Abstract: Main part of this doctoral thesis lies in a study of recom- bination of atomic and molecular ions in low temperature plasmatic environment with emphasis on effect of third bodies. Stationary After- glow equipped with Cavity Ring Down Spectrometer and Cryogenic Flowing Afterglow with Langmuir Probe II were used to obtain recom- bination rate coefficients. Electron assisted collisional radiative recom- bination of Ar+ ion was studied in the temperature range of 50−100 K and helium assisted collisional radiative recombination was observed too. Both H+ 3 and its isotopologue D+ 3 were studies in flowing after- glow and spectroscopically in stationary afterglow as well. Binary re- combination rate coefficients and ternary recombination rate coeffi- cients for helium assisted ternary recombination were determined in the temperature range of 50 − 250 K. These coefficients were deter- mined also for pure ortho- and para- nuclear spin configurations of H+ 3 in the temperature range of 80 − 200 K. Keywords: dissociative recombination, collisional radiative recombi- nation, H+ 3 , D+ 3 , Ar+ viii
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Electron-Ion Recombination at Temperatures below 300K
Kotrík, Tomáš ; Glosík, Juraj (advisor) ; Pysanenko, Andriy (referee) ; Trunec, David (referee)
Title: Recombination study of ions with electrons at temperatures below 300 K Author: Tomáš Kotrík Department: Department of Surface and Plasma Science Supervisor of the doctoral thesis: Prof. RNDr. Juraj Glosík, DrSc. Department of Surface and Plasma Science Abstract: Presented is the study of recombination of ions with electrons performed at low temperatures using the Flowing afterglow with Langmuir probe experimental technique. Studied was the dissociative recombination of H and D ions at temperatures 77 - 300 K. Apart from a two-body also a three-body recombination channel assisted by neutral He atoms was identified and studied. The obtained temperature dependence of the two-body recombination rate coefficient is in a good agreement with findings of other experimental and theoretical works. The dissociative recombination of HCO and DCO ions with electrons was studied in the temperature range 150 - 300 K. The observed temperature dependence of measured recombination rate coefficient for HCO and DCO ions (~T -1.3 and ~T -1.1 , respectively) is in agreement with the majority of previous experimental works and evokes that indirect mechanism governs the recombination process. The electron- assisted collisional-radiative recombination of Ar ions was for the first time studied at temperatures 50 - 300 K. The...
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Recombination of ions in plasma at 50-300 K
Rubovič, Peter
A B S T R A C T Title: Recombination of Ions in Plasma at 50 − 300 K Author: Peter Rubovič Supervisor: Prof. RNDr. Juraj Glosík, DrSc. Abstract: Main part of this doctoral thesis lies in a study of recom- bination of atomic and molecular ions in low temperature plasmatic environment with emphasis on effect of third bodies. Stationary After- glow equipped with Cavity Ring Down Spectrometer and Cryogenic Flowing Afterglow with Langmuir Probe II were used to obtain recom- bination rate coefficients. Electron assisted collisional radiative recom- bination of Ar+ ion was studied in the temperature range of 50−100 K and helium assisted collisional radiative recombination was observed too. Both H+ 3 and its isotopologue D+ 3 were studies in flowing after- glow and spectroscopically in stationary afterglow as well. Binary re- combination rate coefficients and ternary recombination rate coeffi- cients for helium assisted ternary recombination were determined in the temperature range of 50 − 250 K. These coefficients were deter- mined also for pure ortho- and para- nuclear spin configurations of H+ 3 in the temperature range of 80 − 200 K. Keywords: dissociative recombination, collisional radiative recombi- nation, H+ 3 , D+ 3 , Ar+ viii
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Electron-Ion Recombination at Temperatures below 300K
Kotrík, Tomáš
Title: Recombination study of ions with electrons at temperatures below 300 K Author: Tomáš Kotrík Department: Department of Surface and Plasma Science Supervisor of the doctoral thesis: Prof. RNDr. Juraj Glosík, DrSc. Department of Surface and Plasma Science Abstract: Presented is the study of recombination of ions with electrons performed at low temperatures using the Flowing afterglow with Langmuir probe experimental technique. Studied was the dissociative recombination of H and D ions at temperatures 77 - 300 K. Apart from a two-body also a three-body recombination channel assisted by neutral He atoms was identified and studied. The obtained temperature dependence of the two-body recombination rate coefficient is in a good agreement with findings of other experimental and theoretical works. The dissociative recombination of HCO and DCO ions with electrons was studied in the temperature range 150 - 300 K. The observed temperature dependence of measured recombination rate coefficient for HCO and DCO ions (~T -1.3 and ~T -1.1 , respectively) is in agreement with the majority of previous experimental works and evokes that indirect mechanism governs the recombination process. The electron- assisted collisional-radiative recombination of Ar ions was for the first time studied at temperatures 50 - 300 K. The...
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Elementary Processes at Low Temperatures - Reactions of H3+ and N2H+ in Afterglow Plasmas
Kálosi, Ábel ; Plašil, Radek (advisor) ; Rubovič, Peter (referee) ; Španěl, Patrik (referee)
Electron-ion recombination and ion-neutral interactions play a piv- otal role in the chemical evolution of molecules in the Interstellar Medium (ISM). Physical conditions under which these processes un- dergo in the ISM include a wide range of temperatures and particle number densities. This work contributes to the experimental study of named low temperature phenomena in the range of 30 K to 300 K focusing on the reactions of hydrogen-containing light molecules. The employed experimental techniques are based on a combination of a Stationary Afterglow (SA) instrument with a Continuous Wave Cavity Ring-down Spectrometer (cw-CRDS). The main contributions of this work can be split into three topics. (1) The proton and deuteron con- taining isotopic system of H3 + ions. The isotopic fractionation process in collisions with hydrogen and deuterium gas was investigated in low temperature discharges, nominal ion temperatures of 80 K to 140 K, to deduce relative ion densities in the experiments. These are necessary for afterglow studies of isotopic effects in electron-ion recombination of the studied ions. (2) Vibrational spectroscopy of N2H+ ions focusing on first overtone (2ν1 band) transitions and ion thermometry, the first step towards studies of electron-ion recombination. (3) The role of para/ortho spin...
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A model of resonant collisions of electrons with molecules and molecular ions
Váňa, Martin ; Houfek, Karel (advisor) ; Cejnar, Pavel (referee) ; Mašín, Zdeněk (referee)
A two-dimensional model of the resonant electron-molecule collision processes with one nuclear and one electronic degree of freedom introduced by Houfek, Rescigno and McCurdy [Phys. Rev. A 73, 032721 (2006)] and a similar two- dimensional model of the dissociative recombination with potential proposed by Hamilton [Ph.D. thesis, University of Colorado, (2003)] are formulated within the time-dependent framework and solved numerically using the finite-element method with the discrete variable representation basis, the exterior complex scaling method and the generalized Crank-Nicolson method. On the model of electron-molecule collisions we illustrate how the time-dependent calculations can provide a deep insight into the origin of oscillatory structures in the vibrational excitation cross sections if one evaluates the cross sections not only at sufficiently large time to obtain the final cross sections, but rather at several characteristic times which are given by the evolution of the system. With use of the time- dependent calculations we demonstrate the complex nature of the dissociative recombination model dynamics and we propose the interpretation of the recom- bination process mechanism. We also propose few techniques for the explanation of the sharp structures in the dissociative recombination cross sections...
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Recombination of molecular ions with electrons at low temperatures
Kálosi, Ábel ; Plašil, Radek (advisor) ; Kudrna, Pavel (referee)
The aim of this work is the experimental study of recombination of molecular ions with electrons at low temperatures (< 300 K). The work gives an overview of the diagnostic methods, modelling of chemical kinetics, and experimental ap- paratuses Cryo-FALP II and SA-CRDS used in the undertaken measurements. Two processes were studied in the course of this work: state-selective binary disso- ciative recombination of H+ 3 ions in para-H+ 3 and ortho-H+ 3 states, and H2-assisted ternary recombination of H+ 3 . The main result of the state-selective dissociative recombination study is that the rate of recombination in the para-H+ 3 state is at least three times higher than in the ortho-H+ 3 state at 60 K. The study of H2- assisted recombination gave a better understanding of ternary processes of H+ 3 ions and removed further discrepancies between results of afterglow experiments.
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Recombination of ions in plasma at 50-300 K
Rubovič, Peter
A B S T R A C T Title: Recombination of Ions in Plasma at 50 − 300 K Author: Peter Rubovič Supervisor: Prof. RNDr. Juraj Glosík, DrSc. Abstract: Main part of this doctoral thesis lies in a study of recom- bination of atomic and molecular ions in low temperature plasmatic environment with emphasis on effect of third bodies. Stationary After- glow equipped with Cavity Ring Down Spectrometer and Cryogenic Flowing Afterglow with Langmuir Probe II were used to obtain recom- bination rate coefficients. Electron assisted collisional radiative recom- bination of Ar+ ion was studied in the temperature range of 50−100 K and helium assisted collisional radiative recombination was observed too. Both H+ 3 and its isotopologue D+ 3 were studies in flowing after- glow and spectroscopically in stationary afterglow as well. Binary re- combination rate coefficients and ternary recombination rate coeffi- cients for helium assisted ternary recombination were determined in the temperature range of 50 − 250 K. These coefficients were deter- mined also for pure ortho- and para- nuclear spin configurations of H+ 3 in the temperature range of 80 − 200 K. Keywords: dissociative recombination, collisional radiative recombi- nation, H+ 3 , D+ 3 , Ar+ viii
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