5π_{u 1/2}→6sR Bands

Quanta Dependence of the Quantum Yield

Note that the quantum yield for XeF^* excimer formation varies with increasing the bending (ν₂) quantum number. Even if the stretching vibration is excited at 134.50 nm (1¹ transition), the quantum yield has not increased at all. Therefore one can conclude that bending vibration in the excited XeF₂^* molecule promotes excimer formation, but stretching vibration doesn't. This fact may be explained in terms of the enhancement of interaction of this state with the intravalence background states via the bending vibrations.

Since this transition is perpendicular to the molecular axis, the R value decreases at the peaks. The direction of the absorption transition moment is either in the molecular plane or parallel to it. Since the transitions to both directions can contribute to the anisotropy value, the R values determined for these bands turn out to be approximately zero.