화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.102, No.23, 4138-4147, 1998
Ultrafast dynamics of transition metal carbonyls : Photodissociation of Cr(CO)(6) and Cr(CO)(6) (CH3OH)(n) heteroclusters at 280 nm
We report on first results of real-time studies on the photodissociation dynamics of electronically excited Cr(CO)(6) and Cr(CO)(6) .(CH3OH)(n) heteroclusters generated in a molecular beam. The red part of the T-1(1u) metal to ligand charge-transfer state at 280 nm is excited, and the resulting photofragments are detected by multiphoton ionization. The decarbonylation dynamics is found to be much faster than the cross correlation width (230 fs) of our pump and probe pulses. The observed fragmentation pattern and its dynamics can tentatively be attributed to two competing dissociation channels, both starting from the primary photofragment Cr(CO)(5), a simultaneous and a sequential channel. For the clusters we find that both these channels appear to be operative depending on pump laser intensity and that decarbonylation precedes evaporative loss of solvent molecules, which takes place on the picosecond time scale. Solvated cluster species as well as coordinatively unsaturated carbonyls are stabilized by evaporation.