The bond dissociation energies of TiZr, TiNb, and ZrV have been determ
ined by the abrupt onset of predissociation in an extremely congested
vibronic spectrum of these molecules. From these predissociation thres
holds the dissociation energies are determined to be D-o(TiZr) = 2.183
+/- 0.001 eV, D-o(TiNb) = 3.092 +/- 0.001 eV, and D-o(ZrV) = 2.663 +/
- 10.003 eV. After making a correction for the promotion energies requ
ired to prepare the atoms for bonding, the intrinsic bond energies of
these molecules are compared and periodic trends in the bonding of the
3d-4d mixed transition metal dimers are discussed.