Femtosecond quantum dynamics of functional groups under coherent infrared multiphoton excitation as derived from the analysis of high-resolution spectra

Abstract

We report quantum dynamical trajectory results for the femtosecond vibrational motion of various functional groups in organic molecules, associated with the CH infrared chromophore. The dynamics is derived from our previous experimental analysis of high-resolution spectra of this chromophore from fundamental to high-overtone absorption, which allowed us to obtain a «spectroscopic» Hamiltonian for a variety of molecules (also including some ab initio information). The molecular motion is studied in terms of observables during and after coherent, IR-multiphoton excitation. The acetylenic ≡CH group in (CF 3 ) 3 C-C≡H and related molecules shows coherent one-dimensional motion (period 10 fs) for thousands of vibrational periods well into the picosecond time range, without substantial coupling to other modes