HIGH BUFFER GAS-PRESSURE PERTURBATION OF COHERENT POPULATION TRAPPINGIN SODIUM VAPORS

We report an experimental investigation of coherent population trappin g in specially selected Zeeman levels of the sodium atom, performed un der high buffer gas pressure in a polydimethylsiloxane coated cell at room temperature. The results show that coherent population trapping w ill not be completely destroyed when the buffer gas pressure reaches 1 100 Ton for He and 1000, 800, and 500 Ton, for Ne, Ar and Kr, respecti vely. Buffer gases with heavier mass play a larger destructive role fo r the coherent population trapping. The line width of the dark resonan ce is reduced with buffer gas pressure. The behavior of the dark reson ances on increasing buffer gas is discussed and possible applications are pointed out. (C) 1998 Elsevier Science B.V.