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Updated: Aug 18, 2026

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds
Published on: October 12, 2018
Energy flow in push-pull chromophores: vibrational dynamics in para-nitroaniline
Tissa Gunaratne1, J Reddy Challa, M Cather Simpson
1Center for Chemical Dynamics, Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
Abstract:
para-Nitroaniline (PNA) plays an essential role as the prototype model of push-pull chromophores. The nature and degree of participation of vibrational degrees of freedom in the charge-transfer and internal-conversion processes are current issues of great theoretical and practical importance. Ultrafast time-resolved anti-Stokes resonance Raman spectroscopy (TRARRS) experiments on PNA in dimethyl sulfoxide with three different excitation wavelengths were performed to probe these dynamical influences. The vibrational dynamics associated with S0 were independent of incident wavelength, and this supports the picture that the S1 dynamics are fast relative to the rate of intersystem crossing. The phenyl breathing mode nu(19) (860 cm(-1)) and the symmetric NO2 stretch nu(29) (1310 cm(-1)) exhibited vibrational lifetimes in S0 of 8.1 and 5.2 ps, respectively. No evidence for inhomogeneous broadening of the charge-transfer band in the UV/Vis absorption spectrum was found.
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