CONFORMATIONAL-CHANGES ON ELECTRONIC EXCITATION OF THE MERCURY WATER VANDERWAALS COMPLEX

The van der waals complex of mercury with water has been characterized in a supersonic expansion by optical absorption in a region close to the mercury 3P1 <-- 1S0 atomic transition. After excitation the complex dissociates into metastable mercury (3P0) and water, and this appears to be the only open channel. The rotational contours of the bands of a Hg-H2O state assigned to a parallel transition reveal a drastic reduction by 9 wavenumbers of the A rotational constant. This reduction has been explained as being due to a change in geometry from a floppy ground state to a near-C2-upsilon excited complex.