Traditionally our group had used visible
pump-probe to study excited state solvation, isomerization, and other
various effects.
The fact that the same frequency is used as
both the pump and probe beam can complicate these experiments by
allowing competing resonant processes such as excited state
absorption (ESA), stimulated emission (SE), and ground state
recovery (GSR), among others.
If we replace the electronically resonant
probe pulse with a mid-Infrared pulse resonant only with vibrational
transitions and taking advantage of the anharmonicity of the
individual states, we are able to eliminate the electronically resonant
process and focus on vibrational characteristics of each individual
state, thereby elucidating the reaction coordinate.
