Reactions between Cold CHx+ and Slow H and H2
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Dieter Gerlich
Abstract
Using the combination of a linear 22-pole ion trap (22 PT) and a coaxial beam of hydrogen atoms, H abstraction from CHx+ (x=1, 4 and 5) has been studied. The temperature of the trap, T22 PT, can be varied between 10 K and 300 K. The velocity distribution of the neutral target beam can be changed by cooling the accommodator (TACC=10–300 K) and using the focusing features of one or two hexapole magnets. The resulting velocity distributions are characterized by time-of-flight measurements. With the same setup, reactions of mass selected stored ions with a cold effusive beam of H2 molecules have been measured with the discharge turned off. At temperatures of interstellar space, H-abstraction from CH+ is efficient. CH4+ reacts five times faster with H than with H2 at 50 K. In contradiction to ab initio calculations and to the established proton affinity of methane, CH5+ is slowly destroyed in collisions with H in our trap, even at 10 K. Some first results for collisions between CHx+ and D atoms are reported. For x=1, H–D exchange is quite efficient, even though it is in competition with the exothermic abstraction reaction. For x=4, H-abstraction, i.e. formation of HD molecules, dominates. Deuteration of CH5+ is measured to be very slow.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Artikel in diesem Heft
- Editorial
- Reactions between Cold CHx+ and Slow H and H2
- Reactions in Trifluoropropene and Trifluoropropyne Triggered by Low-Energy (0–12 eV) Electrons: From Single Bond Cleavages to Complex Unimolecular Decompositions
- Direct Access to the Dipole-Forbidden nπ∗T1 State of p-Benzoquinone by Photodetachment Photoelectron Spectroscopy
- Quantitative Study of 4He Real Gas Effects Using Supersonic Beams
- Large Amplitude Motions in Cyclopentene and 1-Butene: Quantum Chemical Insights into the Ground- and Excited State Potential Energy Surfaces
- Coherent Excitation Transfer Driven by Torsional Dynamics: a Model Hamiltonian for PPV Type Systems
- H-Bonding Cooperativity Effects in Amyloids: Quantum Mechanical and Molecular Mechanics Study
- Ultrafast Charge Separation at the CdSe Quantum Dot/Methylviologen Interface: Dependence on Electron Acceptor Concentration
- Circular Dichroism in Ion Yields in Multiphoton Ionization of (R)-Propylene Oxide Employing Femtosecond Laser Pulses
- The Interaction of the Dipeptide Carnosine With Alkali Metal Ions Studied by Ion Trap Mass Spectrometry
- Nonequilibrium NMR Methods for Monitoring Protein and RNA Folding
