Accurate ground state potential of Cs2 up to the dissociation limit

Using the method of Doppler-free double resonance polarization spectroscopy transitions from selectively pumped levels (v', J') of the D¹Σ⁺_u state down to levels (v`, J`) of the X ¹Σ⁺_g state with v`= 0-140 have been measured with high accuracy. A long range analysis, based on 21 outer turning points of the IPA potential with v`=110-130 and on calculated exchange energies and second order van der Waals coefficients C_n with n=6, 8, 10, and 12 leads to a dissociation energy D_e =3649.5±0.8 cm^-1 (0.452 49 eV). The influence of the third order C₁₁ contribution and the hyperfine structure on the correct value of D_e are briefly discussed.