Optical pump-terahertz probe spectroscopy of dyes in solutions: probing the dynamics of liquid solvent or solid precipitate?
The optical pump-terahertz probe spectroscopy was used together with ab initio calculations and molecular dynamics simulations to investigate ultrafast dynamics following electronic excitation of Coumarin 153 and TBNC (2,11,20,29-tetra-tert-butyl-2,3-naphtalocyanine) dyes in polar solvents. By scanning the terahertz waveform for different pump-probe delays this experimental technique allows us to obtain two dimensional spectra directly reflecting the temporal response of the system. A distinct signal was obtained for TBNC in chloroform, 2-propanol, and n-butanol, while no signal was recorded for Coumarin 153 in either of these solvents. We explain the nonequilibrium signal detected in TBNC solutions by the presence of a solid, polycrystalline phase of the dye resulting from irradiating the solution by intense optical pulses.
Kadlec
Filip
F
Institute of Physics, Academy of Sciences of the Czech Republic and Center for Complex Molecular Systems and Biomolecules, Na Slovance 2, 18221 Prague 8, Czech Republic.
Kadlec
Christelle
C
Kuzel
Petr
P
Slavícek
Petr
P
Jungwirth
Pavel
P