A pulse radiolysis study of the excitation of nitrogen and aromatic hydrocarbons in rare gas-additive mixtures: Evidence for subexcitation electron interactions
- Univ. of Melbourne, Victoria, Australia
The technique of pulse radiolysis has been used to study the kinetics of formation and decay of excited states in electron-irradiated rare gas/trace additive mixtures. In mixtures of ultrapure helium or neon with nitrogen, the formation of the C/sup 3/II/sub u/ state of N/sub 2/ could be observed via light emission at very low pressures of N/sub 2/. The rate of formation of N/sub 2/ emission was dependent on N/sub 2/ pressure, the emission decay was in agreement with the known radiative lifetime of the C/sup 3/II/sub u/ state, and the kinetics could be described adequately by a sequential two-step process. The dependence of the rate constant for the formation of N/sub 2/(C/sup 3/II/sub u/) on nitrogen pressure yields a second-order rate constant of approximately 5 x 10/sup 12/ dm/sup 3/ mol/sup -1/ s/sup -1/. This precludes any atomic or molecular two-body energy transfer process or collisional relaxation from higher levels created by the initiating pulse of electrons. It is concluded that the excitation of N/sub 2/ is due to electrons of energy between the lowest rare gas energy level and the energy levels of nitrogen, i.e., subexcitation electrons. The rate of formation of nitrogen emission was also dependent on the rare gas pressure but to a much smaller degree than on nitrogen pressure. This effect is directly attributable to the ''cooling'' of epithermal electrons by collisional momentum transfer process. Similar phenomena were obeserved in rare gas/tetracene and rare gas/anthracene mixtures.
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5682267
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:26; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
AROMATICS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FERMIONS
FLUIDS
GASES
HELIUM
HYDROCARBONS
KINETICS
LEPTONS
NEON
NITROGEN
NONMETALS
ORGANIC COMPOUNDS
PRESSURE DEPENDENCE
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOLYSIS
RARE GASES
REACTION KINETICS