... I-38050 Povo, Trento, Italy Darin R. Lather and Mark A. Smith Department of Chemistry, Univer... more ... I-38050 Povo, Trento, Italy Darin R. Lather and Mark A. Smith Department of Chemistry, University of Arizona, Tucson, Arizona 85721 Received: March 30, 1995; In Final Form: June 20, 1995@ Total cross sections, absolute ...
The endothermic reaction N2++N2→N3++N has been investigated both experimentally and by ab initio ... more The endothermic reaction N2++N2→N3++N has been investigated both experimentally and by ab initio calculations. Integral cross sections are presented as a function of collision energy. For excited N2+ ions the reaction onset shifts towards lower energies, indicating that the internal energy of the reactant ions promotes the reaction. Analysis of the energy dependence of the cross section does not allow an unequivocal determination of the reaction endothermicity. However, calculations of the ground doublet surface indicate that the minimum energy path from reactants to products proceeds through strongly bent geometries, with an endothermicity equivalent to the thermodynamic value of about 5 eV. For linear geometries an additional barrier of about 1 eV is found in the product channel. The structure of N4+ in its first excited quartet state has been also calculated by ab initio methods
We report a first observation of optical Ramsey fringes in the 10 ym spectral region using a supe... more We report a first observation of optical Ramsey fringes in the 10 ym spectral region using a supersonic seeded beam of 7% SF, in He, illuminated by a CO laser in spatially-separated field zones. We have used either three standing waves or four travelling waves and obtained highly contrasted fringes with a 23 kHz half-width corresponding to a 5 mm distance between zones.
The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were... more The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were investigated with n = 0,1,2. A drift experiment in the energy range from 0.1 to approximately 1 eV was performed. The product distributions as a function of the relative energy between ions and reactants was determined for some of the reactions.
Journal of Physics E: Scientific Instruments, 1984
The authors have developed a simple interface which adds an analogue signal averaging facility to... more The authors have developed a simple interface which adds an analogue signal averaging facility to any Z80-based microcomputer. The maximum sampling rate is 5 MHz with 8 bits resolution and the maximum memory length is 2048 channels. The interface communicates with the microcomputer through a simple parallel input-output circuit. Data acquisition is handled in parallel with the normal operation of the microcomputer. This paper describes in detail the interface hardware while a listing of the computer program is available from the authors.
As soon as the finite transit time was identified as the basic limitation to ultra-high resolutio... more As soon as the finite transit time was identified as the basic limitation to ultra-high resolution in saturation spec-troscopy, it was suggested' to associate sub-Doppler tech-niques with the method of spatially separated fields intro-duced by Ramsey in the microwave domain around ...
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES, 1989
... Ion Processes, 73 (1986) 237. 12 C. Hagg and I. Szabo, Int. ... 13 Mass filters are supplied ... more ... Ion Processes, 73 (1986) 237. 12 C. Hagg and I. Szabo, Int. ... 13 Mass filters are supplied by Ionentechnik, Innsbruck, Austria; quadrupole power supplies are QM130 by RIAL, Parma, Italy. 14 LSODE package, Lawrence Livermore Radiation Laboratory. ... 8 C. Hägg and I. Szabo. ...
and branching ratios for the reactions Ar++ CH4 and Ne*+CH4 are reported as a function of the col... more and branching ratios for the reactions Ar++ CH4 and Ne*+CH4 are reported as a function of the collision energy, in the range from thermal to 2 eV. Cross-sections are converted to rate coefficients as a function of the translational temperature. The fragmentation of methane as obtained by these reactions is discussed, and compared with dissociative processes of CH4 with Ar* metastable atoms, Ne+ ions and photons. The relevance of collisional processes involving rare gases and methane is discussed in view of their importance for explaining dilution effects in methane plasmas used for carbon and diamond film deposition.
28th International Symposium on Rarefied Gas Dynamics 2012, Vols. 1 and 2, 2012
ABSTRACT Different reactive processes taking place in collisions between alkali ions and neutral ... more ABSTRACT Different reactive processes taking place in collisions between alkali ions and neutral i-C{sub 3}H{sub 7}Cl molecules in the low (center of mass frame) energy range have been studied using an octopole radiofrequency guided-ion-beam apparatus developed in our laboratory. Cross-section energy dependences for all these reactions have been obtained in absolute units. Ab initio electronic structure calculations for those colliding systems evolving on the ground single potential surface have given relevant information on the main topological features of the surfaces. For some of the reactions a dynamic study by 'on the fly' trajectories has complemented the available experimental and electronic structure information.
... I-38050 Povo, Trento, Italy Darin R. Lather and Mark A. Smith Department of Chemistry, Univer... more ... I-38050 Povo, Trento, Italy Darin R. Lather and Mark A. Smith Department of Chemistry, University of Arizona, Tucson, Arizona 85721 Received: March 30, 1995; In Final Form: June 20, 1995@ Total cross sections, absolute ...
The endothermic reaction N2++N2→N3++N has been investigated both experimentally and by ab initio ... more The endothermic reaction N2++N2→N3++N has been investigated both experimentally and by ab initio calculations. Integral cross sections are presented as a function of collision energy. For excited N2+ ions the reaction onset shifts towards lower energies, indicating that the internal energy of the reactant ions promotes the reaction. Analysis of the energy dependence of the cross section does not allow an unequivocal determination of the reaction endothermicity. However, calculations of the ground doublet surface indicate that the minimum energy path from reactants to products proceeds through strongly bent geometries, with an endothermicity equivalent to the thermodynamic value of about 5 eV. For linear geometries an additional barrier of about 1 eV is found in the product channel. The structure of N4+ in its first excited quartet state has been also calculated by ab initio methods
We report a first observation of optical Ramsey fringes in the 10 ym spectral region using a supe... more We report a first observation of optical Ramsey fringes in the 10 ym spectral region using a supersonic seeded beam of 7% SF, in He, illuminated by a CO laser in spatially-separated field zones. We have used either three standing waves or four travelling waves and obtained highly contrasted fringes with a 23 kHz half-width corresponding to a 5 mm distance between zones.
The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were... more The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were investigated with n = 0,1,2. A drift experiment in the energy range from 0.1 to approximately 1 eV was performed. The product distributions as a function of the relative energy between ions and reactants was determined for some of the reactions.
Journal of Physics E: Scientific Instruments, 1984
The authors have developed a simple interface which adds an analogue signal averaging facility to... more The authors have developed a simple interface which adds an analogue signal averaging facility to any Z80-based microcomputer. The maximum sampling rate is 5 MHz with 8 bits resolution and the maximum memory length is 2048 channels. The interface communicates with the microcomputer through a simple parallel input-output circuit. Data acquisition is handled in parallel with the normal operation of the microcomputer. This paper describes in detail the interface hardware while a listing of the computer program is available from the authors.
As soon as the finite transit time was identified as the basic limitation to ultra-high resolutio... more As soon as the finite transit time was identified as the basic limitation to ultra-high resolution in saturation spec-troscopy, it was suggested' to associate sub-Doppler tech-niques with the method of spatially separated fields intro-duced by Ramsey in the microwave domain around ...
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES, 1989
... Ion Processes, 73 (1986) 237. 12 C. Hagg and I. Szabo, Int. ... 13 Mass filters are supplied ... more ... Ion Processes, 73 (1986) 237. 12 C. Hagg and I. Szabo, Int. ... 13 Mass filters are supplied by Ionentechnik, Innsbruck, Austria; quadrupole power supplies are QM130 by RIAL, Parma, Italy. 14 LSODE package, Lawrence Livermore Radiation Laboratory. ... 8 C. Hägg and I. Szabo. ...
and branching ratios for the reactions Ar++ CH4 and Ne*+CH4 are reported as a function of the col... more and branching ratios for the reactions Ar++ CH4 and Ne*+CH4 are reported as a function of the collision energy, in the range from thermal to 2 eV. Cross-sections are converted to rate coefficients as a function of the translational temperature. The fragmentation of methane as obtained by these reactions is discussed, and compared with dissociative processes of CH4 with Ar* metastable atoms, Ne+ ions and photons. The relevance of collisional processes involving rare gases and methane is discussed in view of their importance for explaining dilution effects in methane plasmas used for carbon and diamond film deposition.
28th International Symposium on Rarefied Gas Dynamics 2012, Vols. 1 and 2, 2012
ABSTRACT Different reactive processes taking place in collisions between alkali ions and neutral ... more ABSTRACT Different reactive processes taking place in collisions between alkali ions and neutral i-C{sub 3}H{sub 7}Cl molecules in the low (center of mass frame) energy range have been studied using an octopole radiofrequency guided-ion-beam apparatus developed in our laboratory. Cross-section energy dependences for all these reactions have been obtained in absolute units. Ab initio electronic structure calculations for those colliding systems evolving on the ground single potential surface have given relevant information on the main topological features of the surfaces. For some of the reactions a dynamic study by 'on the fly' trajectories has complemented the available experimental and electronic structure information.
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