Chemical Processes of Ions

Formation - Transport - Reactivity

Numerical wavepacket analysis of photodissociation

The general goal of this project is to advance the theoretical understanding of dissociation dynamics on the femtosecond time scale.

As one example we mention the dissociation of DCl+ ions, which leads to either the formation of D+ and Cl or to D and Cl+ in competing reaction channels. Here we complement our experimental data (see project control) by wavepacket analysis. The analysis is based on the numerical solution of several coupled time dependent Schrödinger equations. The laser parameters of interest are the laser wavelength, the intensity and the chirp. We have e.g. found that the control of branching ratios is easily feasible in particular in the mid infrared region (s. Fig. 1) and ref. [1]. We have also demonstrated the possibility to control the branching ratio by choice of the appropriate carrier envelope phase (CEP) (s. Fig. 2 and ref. [2]).

Fig. 1  Frequency dependence of the relative ion yields of D⁺ and Cl⁺ in the fs dissociation of DCl⁺ in the mid IR [1].

Fig. 2              CEP dependence of fragment and parent ion yields in DCl⁺ at w=1558 cm^-1 for negative chirp. Intensity:   I = 896 TW/cm² [2].

Literature

[1]        M.V. Korolkov, K.-M. Weitzel, J. Chem. Phys., J.Chem. Phys., 123, 164308, (2005)
On the Control of Product Yields in the Photofragmentation of Deuteriumchlorid Ions (DCl⁺),   http://dx.doi.org/10.1063/1.8207667

[2]        M.V. Korolkov, K.-M. Weitzel, Chem. Phys.,  338, 277-284, (2007)
Laser pulse control of photofragmentation in DCl⁺: the effect of carrier envelope phase,  http://dx.doi.org/10.1016/j.chemphys.2007.03.007