Total collision cross sections between alkali atoms at thermal energies

It is shown that the total collision cross section between two alkali atoms at a thermal velocity v is not given simply by the Massey-Mohr equation: where A is a constant and C is the long-range inverse-six potential constant. Experimental cross sections should either show oscillations about this value as a function of velocity if the triplet potential minimum is deep enough, or should fall below this value with a different velocity dependence if the triplet minimum is shallow.