Change in the States of Optically Excited Rb Atoms
near Sapphire Surface

T. A. Vartanyan^a, A. E. Logunov^a, A. S. Pazgalev^b, S. G. Przhibel’skii^a,
D. Sarkisyan^c, and V. V. Khromov^a

^a National Research University of Information Technologies, Mechanics, and Optics, St. Petersburg, 197101 Russia

^b Ioffe Physical Technical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021 Russia

^c Institute for Physical Research, National Academy of Sciences of Armenia, 0203 Ashtarak-2, Armenia

e-mail: przhi@mail.ru

Received December 20, 2012

Abstract—The changes in the states of excited Rb atoms approaching a single-crystal sapphire surface have
been investigated by methods of laser-excitation spectroscopy and luminescence of Rb vapor in a cell with sap-
phire windows, the gap between which was varied from 250 to 500 nm. Upon resonant excitation of Rb atoms
by two semiconductor lasers with powers of 20 and 40 mW, luminescence from optically excited 5D_3/2 and
5D_5/2 states and optically unexcited 6P_1/2 and 6P_3/2 states is observed. It is established that the luminescence
intensity from unexcited states is only a few times lower than that from excited states, with allowance for the
fact that excited atoms are rapidly and almost completely quenched on the sapphire surface. The found anom-
alously strong luminescence from optically unexcited 6P_J states is explained by their nonradiative occupation
near the sapphire surface from optically excited 5D_J states, in which atoms fail to reach the sapphire surface
because of the repulsion from it. This repulsion is due to the polarization interaction between sapphire and the
atoms in the 5D_J states near the surface. Nonradiative transition from the 5D_J state to the 6P_J–1 state is accom-
panied by excitation of two optical phonons in sapphire.

DOI: 10.1134/S0030400X13070217

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