Spin polarization of $^{85}$Rb atoms in collisions with optically oriented metastable $^{4}$He atoms in alkali–helium plasma

We have experimentally detected a signal of magnetic resonance (MR) from $^{85}$Rb atoms in the 5$^{2}$S$_{1/2}$ state by measuring the absorption of light from a helium lamp producing optical orientation of metastable 2$^{3}$S$_{1}$ $^{4}$He atoms in a cell containing alkali metal vapor and gaseous helium at a pressure of 1 Torr. The ratio of MR signal amplitudes in Rb and He atoms did not exceed 10$^{-2}$. Peculiarities of the formation and observation of the collisional polarization of Rb atoms in alkali–helium plasma are discussed.