Control of ultrafast charge migration in molecules
In recent years, the rapid development of attosecond pulse techniques opened the door for studying and eventually controlling electronic dynamics. Due to coupling between the electronic and nuclear motion, control over the pure electronic step offers the extremely interesting possibility to steer the succeeding chemical reactivity by predetermining the reaction outcome at a very early stage. Using the electron dynamics and quantum coherence to induce a particular chemical process is the new paradigm in the emerging field of “attochemistry”.
One example of physical phenomena, where an electronic dynamics significantly affect on reactivity is the process of an ultrafast charge migration. The positive charge created upon ionization of a molecule can migrate throughout the system on a few-femtosecond time scale solely driven by the electron correlation and electron relaxation. Charge migration triggered by ionization appeared to be a general phenomenon taking place both after inner- and outer-valence ionization of molecules.
A realistic showcase example for which after an outervalence ionization a strong charge migration takes place is the 3-methylen-4-penten-N,N-dimethylamine (MePeNNA) molecule. The outervalence part of the ionization spectrum of the molecule consists of two ionic states. These two states can be simultaneously populated via a laser pulse with photon energy centered between the two states and a bandwidth sufficient to embrace both of them. Immediately after the ionization the hole starts to oscillate between a chromophore and amine moieties of the system with a half-period of about 4 fs.
Here a scheme to control the many-body electron dynamics of the charge migration process by a single ultrashort laser pulse is presented. By appropriately tailored infrared pulses one can stop the pure electronic, few-femtosecond oscillation of the charge, localizing it on the desired site of the MePeNNA molecule.
- L. S. Cederbaum and J. Zobeley
Ultrafast charge migration by electron correlation
Chem. Phys. Lett. 307, 205 (1999)
- N. V. Golubev and A. I. Kuleff
Control of charge migration in molecules by ultrashort laser pulses
Phys. Rev. A 91, 051401(R) (2015)
- Quantum Control with Smoothly Varying Pulses: General Theory and Application to Charge Migration
Journal of Modern Optics, 64 (10-11), 1031 (2017)