Collision energy pooling for Sr(5${\mathrm{}}^3$${\mathit{P}}_{\mathit{J}}$)+Sr(5${\mathrm{}}_{\mathit{J}\mathcal{’}}^3$) → Sr(6${\mathrm{}}^{3,1}$S)+Sr(5${\mathrm{}}^1$S)

Energy pooling (EP) has been observed in Sr vapor following pulsed optical excitation to the 5${}^3$ $P_1$ state. From the time-dependent radiative decay of 6${}^3$ $S_1$ and of $6^1$ ${\mathit{S}}_0$ via the cascade resonance line, the EP rate coefficients have been investigated for the following: Sr(5 ${}_{}{}^3{}_{}{}^{}P_J^{}{}_{}{}^{}$)+Sr(5${}^3$ ${\mathit{P}}_{\mathit{J}\mathcal{’}}$) &Sr${(5\mathrm{}}^1$ $S_0$) +Sr(6 ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ or $6^1$ $S_0$). The values of $k_{11}$ have been measured, as well as $k_{\mathrm{JJ}\mathcal{’}}$ averaged over a thermal distribution of 5 ${}_{}{}^3{}_{}{}^{}P_J^{}{}_{}{}^{}$ populations. The time-dependent Sr($5^3$ $P_J$) densities were measured by absorption of lines from a Sr lamp crossing the excitation region. The rate coefficients are surprisingly large; in spite of the small statistical weights of these product states, they are nearly gas-kinetic. The dependence of the rates upon spin, J, and energy defect ΔE has also been examined.