The water vapor 0.27 mkm absorption band: Hypothesis of band strengthening.

The analysis of interaction between the ground (X) over tildeA(1)(1) and excited (B) over tilde (1)A(1) electronic states of the water molecule have been made and it was shown that the centrifugal distortion near the linear HOH configuration may lead to a considerable state mixing in the case when both lower and upper state wave functions are localised near linear configuration. As a result, transitions to the high-bending states, such as (0V(2)0) with V(2)similar to20, within the ground electronic state may be intense due to intensity borrowing. This effect appears to explain the weak 0.27 mkm feature in the near UV water vapor spectrum observed early experimentally.