Efficient Vibrational Energy Transfer through Covalent Bond in Indigo Carmine Revealed by Nonlinear IR Spectroscopy.

J Phys Chem B 2017 10 28;121(40):9411-9421. Epub 2017 Sep 28.

Beijing National Laboratory for Molecular Sciences, Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.

Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump-probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-bonded C═O and delocalized C═C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited C═O stretching mode was found to occur through covalent bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump-probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the C═O and C═C transition frequency (33 cm). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited C═O stretching was believed to be a nearby combination and/or overtone mode that is more tightly connected to the C═O species. On the structural aspect, dynamical-time-dependent 2D IR spectra reveal an insignificant inhomogeneous contribution to time-correlation relaxation for both the C═O and C═C stretching modes, which is in agreement with the generally believed structural rigidity of such conjugated molecules.

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jpcb.7b06766DOI Listing
October 2017
11 Reads

Publication Analysis

Top Keywords

excited c═o
8
covalent bond
8
c═c stretching
8
indigo carmine
8
energy transfer
8
c═o stretching
8
c═o c═c
8
stretching modes
8
vibrational energy
8
c═o
6
cross-peak dynamics
4
dynamics showing
4
observed magic-angle
4
pump-probe anisotropy
4
magic-angle pump-probe
4
anisotropy cross-peak
4
1010 corresponds
4
difference c═o
4
c═c transition
4
energy difference
4

Similar Publications