Measurement of the electron collision quenching rates of some excited states of Cd I in a He-Cd discharge
- 14 April 1986
- journal article
- Published by IOP Publishing in Journal of Physics D: Applied Physics
- Vol. 19 (4) , 503-511
- https://doi.org/10.1088/0022-3727/19/4/007
Abstract
Electron collisional quenching rate coefficients and radiative lifetimes of the 71S, 61D, 51D, 53D and 63S states of Cd I are investigated by means of time-resolved, laser-induced fluorescence spectroscopy in the positive column of a helium-cadmium discharge (i=0-200 mA, PHe=1-6 Torr, nCd=1012-3*1014 cm-3). The collisional rate coefficients measured for the first time are 5.2+or-0.6, 2.3+or-0.8, 07+or-0.2 in units of 10-5 cm3 s-1 for the 61D, 71S and 51D states respectively. Assuming that these quenching collisions are due to collisions towards the neighbouring levels connected by a dipolar interaction, hydrogenic formulas based on the Born-Bethe cross section correctly fit experimental values. The radiative lifetimes deduced from this experiment are found to be in good agreement with those of previous works. In particular, the radiation processes are, for the 5D and 6S triplet states, the dominant part of the quenching. Finally, from the peak amplitude of the LIF signals it is shown that the low-lying 5P states can be described in the discharge by a coronal equilibrium whereas the upper levels are in a collisional one.Keywords
This publication has 14 references indexed in Scilit:
- Collisional processes induced in the n=3 helium sublevels by electrons in a low-pressure plasma. Application to the electron density measurementJournal of Physics B: Atomic and Molecular Physics, 1985
- Mesure de durees de vie radiatives de niveaux de triplet du cadmium par spectroscopie laser resolue dans le tempsOptics Communications, 1983
- Direct determination of ratios of electron and Penning excitation rates for Cd(II) excited states in the positive column He-Cd+laser dischargeJournal of Physics D: Applied Physics, 1982
- Competition between different excitation processes of the Cd(II) 5s22D5/2state at low discharge currents in the positive column He-Cd+laser dischargeJournal of Physics D: Applied Physics, 1981
- A new design concept for hollow-cathode white light laserIEEE Journal of Quantum Electronics, 1980
- Quenching and excitation transfer in thehelium sublevels in a low-pressure glow dischargePhysical Review A, 1980
- Modified absorption method to determine level population densities in a cataphoresis type of He-metal laser dischargeApplied Physics Letters, 1976
- Radiative lifetimes in Zn(II), Cd(II) and Hg(II) measured by fast-beam zero-field level-crossing techniqueJournal of Quantitative Spectroscopy and Radiative Transfer, 1976
- Excitation mechanisms in He–Cd and He–Zn ion lasersJournal of Applied Physics, 1973
- Metastable densities and excitation processes in the He-Cd laser dischargeJournal of Physics B: Atomic and Molecular Physics, 1973