Selective reflection of light from dense sodium vapors

The resonant collisional broadening of the D1 and D2lines of sodium atoms was studied by the method of selective reflection of light for vapor pressures up to 5x1018 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 D1 and D2 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