1. Electronically Resonant Coherent Multidimensional Vibrational Spectroscopy
John C. Wright, Department of Chemistry, University of Wisconsin- Madison
Coherent Multidimensional FWM Spectroscopy is performed by
tuning three excitation frequencies to molecular transitions that
excite transitions from the ground state, g, to either state a or s.
The excitations create the coherences indicated by the two letters.
Dotted arrows indicate coherence transfer transitions where the
thermal bath causes an entanglement of two states to evolve to
a different entanglement. The coherences indicated by boxes emit
light. The black box arises from purely radiative excitations while
the red boxes arise from coherence transfer. The 2a, s coherence
emission is forbidden so the coherence transfer emission can dominate.
A monochromator can discriminate against the different output frequencies
and isolate the a particular set of coherence transfer pathways. Since there
are multiple pathways to a given output coherence, the pathways interfere
and create modulations when the time delays between the three pulses are
changed. The figure to the left shows such modulations. Coherence transfer
provides a new way to perform multidimensional spectroscopy and identify
coupling between different quantum states.
-J. Phys. Chem. 111, 1163 (2007)