Selective reflection of light from dense sodium vapors

The resonant collisional broadening of the D-1 and D-2 lines of sodium atoms was studied by the method of selective reflection of light for vapor pressures up to 5 x 10(18) cm(-3). As the collisional line broadening becomes comparable to the fine splitting, the spectrum of selective reflection exhibits the interrelation between the contributions of the D-1 and D-2 lines with a continuous change from the doublet structure to the singlet one. The experimental data were found to be in good agreement with calculations based on the model of binary collisions.