6. Characteristic Quantum Threshold Temperatures T _Q above which Semiclassical Methods Hold, as Derived by Julienne and Mies for Collisions of Species in Specified States Subject to van der Waals Potentials of Force Power n .

Species	State	n	T Q
H + H	${{}^1\mathrm{\Sigma }}_g^{+}$	6	20 K
$\mathrm{He}({}^{3}S)+\mathrm{He}({}^{3}S)$	${{}^1\mathrm{\Sigma }}_g^{+}$	6	100 mK
Cs + Cs	${{}^1\mathrm{\Sigma }}_g^{+}$	6	300 μK
Na + Na	${{}^1\mathrm{\Sigma }}_g^{+}$	6	10 mK
$\mathrm{Na}({{}^{2}P}_{3/2})+\mathrm{Na}({{}^{2}P}_{3/2})$	1 u	5	740 μK
$\mathrm{Na}({{}^{2}P}_{3/2})+\mathrm{Na}$	0 u	3	1 nK

^aNote T _Q occurs in the ultracold regime for collisions of Cs + Cs, $\mathrm{Na}({{}^{2}P}_{3/2})+\mathrm{Na}({{}^{2}P}_{3/2})$ , and $\mathrm{Na}({{}^{2}P}_{3/2})+\mathrm{Na}$ and in the cold regime for $\mathrm{He}({}^{3}S)+\mathrm{He}({}^{3}S)$ and Na + Na. Reproduced with permission from ref . Copyright Optical Society of America.