Junior research group Theoretical Chemistry
Ultrafast Dynamics and Time-resolved Spectroscopy
Time-resolved nonlinear spectroscopy
There is a huge variety of experimental techniques in the field of time-resolved optical spectroscopy.
The easiest to interprete is time-resolved fluorescence: the emitted photons (recorded as a funtction of time) reflect directly
the ultrafast dynamics in optically bright electronic states.
But it is the hardest to detect experimentally.
That is why a number of the so-called four-wave mixing (4WM) techniques has been developed.
They include transient transmittance pump-probe, time-resolved coherent anti-Stokes Raman scattering (CARS),
two- and three-pulse photon echo,
transient grating, etc.
In particular two-dimensional (2D) electronic photon-echo spectroscopy
is especially sensitive
and allows to monitor the system coherences in real time.
wave-packet dynamics vs. time-resolved fluorescence
Although experiments provide an immense amount of information,
it is indirect and requires a detailed analysis for an unambiguous interpretation.
The measured signals depend both on the system dynamics and on the laser pulse properties,
proper simulations are necessary to facilitate interpretation of experimental results,
and to provide guidance for further investigations.
We develop and employ novel efficient methods for calculation
of the time- and frequency-resolved optical signals.
The methods allow for system Hamiltonians of arbitrary
have no limitations with respect to pulse durations and automatically account for pulse-overlap effects.
We are able to accurately and efficiently calculate observables of
all the most frequently employed investigation schemes.
Our most universal tool is the equation-of-
motion phase-matching approach (EOM-PMA).
It allows for a straightforward calculation of any N-wave mixing signal and can be
implemented within various dynamical descriptions
based either on density-matrix
or wave-function formalisms.
EOM-PMA has been implemented for simulations of homodyne and heterodyne
photon-echo signals by several research groups.
- M. Gelin, D. Egorova, W. Domcke, A new method for the calculation of two-pulse time- and frequency-resolved spectra, Chem. Phys. 312 (2005) 135
- D. Egorova, M. Gelin, W. Domcke, Efficient method for the calculation of time- and frequency-resolved four-wave mixing signals
and its application to photon-echo spectroscopy, J. Chem. Phys. 123 (2005) 164112.
- M. Gelin, D. Egorova, W. Domcke, Efficient calculation of the polarization induced by N coherent laser pulses, J. Chem. Phys. 131 (2009) 194103.
- M. Gelin, D. Egorova, W. Domcke,
Optical N-Wave-Mixing Spectroscopy with Strong and Temporally Well-Separated Pulses: The Doorway-Window Representation, J. Phys. Chem. B 115 (2011) 5648.
- D. Egorova,
Oscillations in two-dimensional photon-echo signals of excitonic and vibronic systems: Stick-spectrum analysis and its computational verification ,
J. Chem. Phys. 140 (2014) 034314.
Back to Methods
Back to Research Overview
Back to Home