Collisional broadening of some 2^1Delta_g<--B^1Pi_u lines in ...

Using the optical-optical double resonance (OODR) technique, we have studied the collisional broadening of some 2^1Delta_g<--B^1Pi_u lines in Na2 molecules. A single line Ar+ laser is used to pump the sodium dimers from thermally populated ground state X^1Sigma+_g level to the intermediate B^1Pi_u state. Then, a single-mode diode laser is used to probe the doubly excited 2^1Delta_g state. The broadening rate coefficient is determined from the slope of the total linewidth versus Ne density curve.