Quasiclassical calculations of BBR-induced depopulation rates and   effective lifetimes of Rydberg nS, nP and nD alkali-metal atoms with n < 80
  Rates of depopulation by blackbody radiation (BBR) and effective lifetimes of alkali-metal \textit{nS}, \textit{n}P and \textit{nD} Rydberg states have been calculated in a wide range of principal quantum numbers $n \le 80$ at the ambient temperatures of 77, 300 and 600 K. Quasiclassical formulas were used to calculate the radial matrix elements of the dipole transitions from Rydberg states. Good agreement of our numerical results with the available theoretical and experimental data has been found. We have also obtained simple analytical formulas for estimates of effective lifetimes and BBR-induced depopulation rates, which well agree with the numerical data. 
I.I.Beterov, I.I.Ryabtsev, D.B.Tretyakov, V.M.Entin