Dissociative recombination as primary dissociation channel in plasma chemistry

Aims. The aim of this work is to furnish branching ratios (BRs) to the kinetic databases used in astrochemistry such as the KInetic Database for Astrochemistry (KIDA). This concerns CHy(+) species (y = 2–4) excited by cosmic rays, electrons and photons, or the intermediate excited complexes CHy(+) resulting from a chemical reaction. Methods. The full set of fragmentation branching ratios following CHy(+) (y = 2,4) of constant velocity (250 keV uma−1) colliding with He atoms has been measured with the multidetector AGAT. Kinetic energy distributions of neutral fragments produced in each dissociation channel have been also measured. With these experimental inputs, and theoretical dissociation energies, semiempirical breakdown curves (BDCs) have been constructed. Results. Prediction of BRs with the present BDCs is found to agree with available BR measurements for electronic dissociative recombination, collision with fast electron and photodissociation. Dependence of BRs with the various UV fields relevant to interstellar medium and planetary atmospheres is predicted.

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Dissociative recombination of molecular ions in noble-gas plasmas

Uspekhi Fizicheskih Nauk ◽

10.3367/ufnr.0162.199201b.0035 ◽

1992 ◽

Vol 162 (1) ◽

pp. 35 ◽

Cited By ~ 40

Author(s):

V.A. Ivanov

Keyword(s):

Noble Gas ◽

Dissociative Recombination ◽

Molecular Ions

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Dissociative recombination of electrons and molecular ions

Uspekhi Fizicheskih Nauk ◽

10.3367/ufnr.0136.198201b.0025 ◽

1982 ◽

Vol 136 (1) ◽

pp. 25 ◽

Cited By ~ 48

Author(s):

Aleksandr V. Eletskii ◽

Boris M. Smirnov

Keyword(s):

Dissociative Recombination ◽

Molecular Ions

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Material Structure of Microcrystalline Silicon Deposited with an Expanding Thermal Plasma

MRS Proceedings ◽

10.1557/proc-762-a.15.3 ◽

2003 ◽

Vol 762 ◽

Cited By ~ 2

Author(s):

C. Smit ◽

D.L. Williamson ◽

M.C.M. van de Sanden ◽

R.A.C.M.M. van Swaaij

Keyword(s):

Thermal Plasma ◽

Hydrogen Plasma ◽

Plasma Chemistry ◽

Plasma Source ◽

Growth Direction ◽

Interaction Time ◽

Material Structure ◽

Average Particle ◽

Microcrystalline Silicon ◽

X Ray

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.

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