scholarly journals A mass-selective ion transfer line coupled with a uniform supersonic flow for studying ion–molecule reactions at low temperatures

2019 ◽  
Vol 150 (16) ◽  
pp. 164201 ◽  
Author(s):  
B. Joalland ◽  
N. Jamal-Eddine ◽  
D. Papanastasiou ◽  
A. Lekkas ◽  
S. Carles ◽  
...  
Keyword(s):  
Supersonic Flow ◽  
Low Temperatures ◽  
Ion Transfer ◽  
Ion Molecule Reactions ◽  
Transfer Line

Molecular-physics aspects of cold chemistry

2019 ◽  
pp. 82-141
Author(s):  
FrÉdÉric Merkt
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Molecular Physics ◽  
Exothermic Reactions ◽  
Langevin Model ◽  
Ion Molecule Reactions ◽  
Radiative Association ◽  
Association Reaction ◽  
Oppenheimer Approximation ◽  
General Aspects

Molecular-physics aspects of cold chemistry are introduced with the example of few-electron molecules. After a brief overview of general aspects of molecular physics, the solution of the molecular Schrödinger equation is presented based on the Born-Oppenheimer approximation and the subsequent evaluation of adiabatic, nonadiabatic, relativistic and radiative (QED) corrections. Low-temperature chemical phenomena are introduced with the example of ion-molecule reactions, using the classical Langevin model for barrier-free exothermic reactions as reference. Then, methods to generate cold few-electron molecules by supersonic-beam-deceleration methods such as Stark, Zeeman, and Rydberg-Stark decelerations are presented. Two astrophysically important reactions, the reaction between H2 and H2+ forming H3+ and H, a very fast reaction following Langevin-capture going over to quantum-Langevin capture at low temperature, and the radiative association reaction H+ + H forming H2+, a very slow reaction in which quantum effects (shape resonances) become important at low temperatures, are used to illustrate the concepts introduced.

scholarly journals Cover Picture: New Method to Study Ion-Molecule Reactions at Low Temperatures and Application to the H2++H2→H3++H Reaction (ChemPhysChem 22/2016)

ChemPhysChem ◽  
2016 ◽  
Vol 17 (22) ◽  
pp. 3578-3578 ◽  
Author(s):  
Pitt Allmendinger ◽  
Johannes Deiglmayr ◽  
Otto Schullian ◽  
Katharina Höveler ◽  
Josef A. Agner ◽  
...  
Keyword(s):  
Low Temperatures ◽  
New Method ◽  
Ion Molecule Reactions

scholarly journals New Method to Study Ion-Molecule Reactions at Low Temperatures and Application to the H2++H2→H3++H Reaction

ChemPhysChem ◽  
2016 ◽  
Vol 17 (22) ◽  
pp. 3580-3580
Author(s):  
Pitt Allmendinger ◽  
Johannes Deiglmayr ◽  
Otto Schullian ◽  
Katharina Höveler ◽  
Josef A. Agner ◽  
...  
Keyword(s):  
Low Temperatures ◽  
New Method ◽  
Ion Molecule Reactions

scholarly journals Preliminary Design of the Support Structure for a Rotating Carbon-ion Transfer Line for Medical Applications

Instruments ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 34
Author(s):  
Diego Perini ◽  
Luca Dassa ◽  
Luca Piacentini ◽  
Stefano Uberti
Keyword(s):  
Superconducting Magnets ◽  
Medical Applications ◽  
Preliminary Design ◽  
Ion Transfer ◽  
Carbon Ions ◽  
Support Structure ◽  
Beam Position ◽  
Carbon Ion ◽  
Transfer Line ◽  
Rotating Structure

The development of new bent superconducting magnets together with the optimization of the support structure open the way to a considerable reduction in the weight and complexity of rotating gantries for medical applications. The magnets, which define the transfer line to deliver carbon ions to the patients from different angles, are supported by a rotating structure that should be as rigid and as lightweight as possible. Relative displacements of the magnets due to deformations cause incorrect beam position and consequent errors in hitting the target tissues. This paper describes a possible rotating structure which is considerably lighter than the previous designs. A method to compensate part of the deformation by complementary rotations of the driving motor is proposed. The influence of the construction tolerances and deformations of the supports is also analyzed and alignment and adjustment possibilities are discussed.

Laboratory studies of isotope exchange in ion-neutral reactions: interstellar implications

1981 ◽  
Vol 303 (1480) ◽  
pp. 535-542 ◽  
Keyword(s):  
Low Temperatures ◽  
Isotope Exchange ◽  
Laboratory Data ◽  
Isotopic Ratios ◽  
Laboratory Studies ◽  
Terrestrial Environment ◽  
Interstellar Clouds ◽  
Ion Molecule Reactions ◽  
Significant Process ◽  
Molecule Interactions

The rare stable isotopes of several elements (e.g. D, 13 C and 15 N) have been detected in several interstellar molecules, and their abundance relative to the more common isotope is often enhanced above that in the solar-terrestrial environment. Important questions to answer are to what extent the isotopic ratios in the molecules are representative of those in the cloud matter as a whole, and whether fractionation of the heavier isotope into the molecules via ion—molecule interactions is a significant process. A laboratory study of isotope exchange in ion-molecule reactions has therefore been carried out, the results of which indicate that fractionation of heavy isotopes can occur very efficiently at low temperatures. Consideration is given in this paper to reactions in which H-D, 12 C - 13 C, 14 N - 15 N and 16 O - 18 O exchange occurs, and it is shown how better estimates of the electron density and the temperature in interstellar clouds have been obtained from these laboratory data.

Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

1970 ◽  
Vol 23 (5) ◽  
pp. 893 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
High Pressures ◽  
Rate Coefficients ◽  
Ion Transfer ◽  
Ion Energy ◽  
Transfer Processes ◽  
Ion Molecule Reactions ◽  
Ionic Systems ◽  
Derivatives Of

The ion-molecule reactions of eight highly halogenated derivatives of methane were studied in the gas phase using a mass spectrometer operated at high pressures. The compounds studied were CHCl3, CHCl2F, CHClF2, CHF3, CCl4, CCl2F2, CClF3, and CF4. These ionic systems were found to be less reactive than those of methane or the methyl and methylene halides. The main reactions observed were described as being halide ion transfer processes. The energy dependence of the cross sections and the rate coefficients of the reactant ions were determined.� Many rate coefficients for reactions between ions and polar molecules were found to be independent of the ion energy. Brief studies of the negative spectra at high pressures were also made.

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