Recombination of polycyclic aromatic hydrocarbon photoions with electrons in a flowing afterglow plasma

Journal Article · Thu Sep 08 00:00:00 EDT 2005 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2000927· OSTI ID:20723062

Novotny, O; Sivaraman, B; Rebrion-Rowe, C; Travers, D; Biennier, L; Mitchell, J B.A.; Rowe, B R ^[1]

---

1. Laboratoire de Physique des Atomes, Lasers, Molecules et Surfaces (PALMS), Unite Mixte de Recherche (UMR), No. 6627 du Centre National de la Recherche Scientifique - CNRS, Universite de Rennes I, 35042 Rennes (France)

A new technique, flowing afterglow with photoions (FIAPI), has been developed to measure the rate coefficient for the recombination of complex ions, and, in particular, polycyclic aromatic hydrocarbon (PAH) cations with electrons. The method is based on the flowing afterglow Langmuir probe - mass spectrometer apparatus at the University of Rennes I. A helium plasma is generated by a microwave discharge in a He buffer gas and downstream, a small amount of argon gas is injected to destroy any helium metastables. A very small amount of neutral PAH molecules is added to the afterglow plasma by evaporation from a plate coated with the PAH to be studied. PAH ions are then produced by photoionization of the parent molecule using a pulsed UV laser (157 nm). The laser beam is oriented along the flow tube and so a constant spatial concentration of photoions is obtained. The electron concentration along the flow tube is measured by means of a movable Langmuir probe. Ion concentration decay in time is measured at a fixed position using a quadrupole mass spectrometer which is triggered by the laser pulse. The recombination of anthracene and pyrene cations has been studied using this technique and we have found a recombination rate of (2.4{+-}0.8)x10{sup -6} cm{sup 3} s{sup -1} for anthracene and (4.1{+-}1.2)x10{sup -6} cm{sup 3} s{sup -1} for pyrene.

• OSTI ID: 20723062
• Journal Information: Journal of Chemical Physics, Vol. 123, Issue 10; Other Information: DOI: 10.1063/1.2000927; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AFTERGLOW
ANTHRACENE
ARGON
CATIONS
ELECTRONS
HELIUM
HIGH-FREQUENCY DISCHARGES
LANGMUIR PROBE
MASS SPECTROMETERS
MASS SPECTROSCOPY
PHOTOIONIZATION
PHOTON-MOLECULE COLLISIONS
PLASMA
PLASMA PRODUCTION
POLYCYCLIC AROMATIC HYDROCARBONS
PYRENE
REACTION KINETICS
RECOMBINATION