dissociation, E, of a dimer into two monomers and that, E', of a trimer
into a dimer and a monomer. The observed velocity distribution for a
beam of sodium iodide is shown in Fig. 23. The monomer and dimer
distributions, which are each of the form of Eq. (9. 2), are separately
shown. The sum of the two assumed distributions is seen to agree with
the experimental data. The data for lithium bromide are shown in Fig.
24. The separate distributions for the monomer, dimer, and trimer
required to fit the data are shown as is the sum of these distributions.
An attempt to describe the observed distribution in terms of a monomer
and a dimer only is shown by the dotted line, where the relative amounts
of these species have been adjusted to give a fit on the low velocity
side of the spectrum. Table 2. Summary oj data on the degree of
association oj diatomic molecules. The data on the fluorides are from
unpublished results of M. EISENSTADT, G. ROTHBERG and P. KUSCH.
Uncertainties in E and E' are given in parentheses. E E' Temperature OK
I ----- ----" Species at which a2 a, kcaljmole p 10-2mmHg RbCl 866 0.
063 48. 0 (0. 5) I KCI 0. 083 897 45-8 (0. 7) I KI 823 0. 046, 45-3
(0-9) NaC] 920 0. 259 44. 6 (0-9) i NaI 817 0. 235 38. 6 (3-4) LiC] 2.