COMPETING BOND FRAGMENTATION

In general, we are interested in developing laser strategies which can break a desired bond in a molecular system.

HALOMETHANES
For instance, can we break the strong bond versus the weak bond in a molecule? CH2BrCl is a good example: we'd like to break the C-Cl bond without producing C-Br fragmentation.  In this kind of molecules it is known that  control is probably  possible through control of the non-adiabatic effects. We are currently calculating the potential energy surfaces for excited states of CH2BrCl, in order to explore the non-adiabatic dynamics and develope control strategies.

HYDROGEN  BONDS (within the Graduiertenkolleg GK788 )
Systems presenting hydrogen bonds can also be good candidates to exert selective bond breaking. This is the case of XHY- anions, in which X and Y are strongly bound through a hydrogen bond.

Using the simplest of these molecules FHF- we are using very short IR lasers with few cycles to induce wave packet dynamics in the electronic ground state. This produces a vibration of the H between the two heavy atoms, which can be controlled by a UV laser pulse which photodetaches the electron. If the sequence of IR and UV pulses is timed adequately, selective bond breaking can be achieved.

We are now working on OHF-, for which we could invert the natural branching ratio of the system!

Same strategy (IR+UV) has been applied in the HOD molecule, in this case, making use of the transfer of momentum by the vertical transition.

Wanna know more?

See publication list.