Kinetics of collisional ionization of alkali metal atoms and recombination of electrons with alkali metal ions in flames

• Published in: Combustion and flame 1973-08, Vol.21 (1), p.69-75
• Main Authors: Ashton, A.F., Hayhurst, A.N.
• Format: Article
• Language: English
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/0010-2180(73)90008-4

The rate constant k2 has been measured in flames of H2 + O2 + N2 for the ionization of alkali metal atoms M in collisions with flame species X in M+X→M++e−+X. Results are compared with every previously reported measurement of k2 in similar flames for each alkali metal. It is concluded that k2=(9.9±2.7)×10−9T1/2exp⁡(−V/RT), ml molecule −1 sec−1, where V is the ionization potential of the alkali metal atom and T the temperature. k2 does not depend on flame composition and is the same for each alkali to a good approximation. The third-order recombination rate constant k−2 for the reverse of (II) can be written as k−2=(4.1±1.1)×10−24T−1, ml2 molecule−2 sec−1. There is no significant dependence of k−2 on flame composition or on which alkali metal is considered. These facts enable the rates of the forward and reverse processes in (II) to be estimated in flames generally.