Knowledge Bank

The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene ($\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$), $\backslash ~X1\Sigma g+$ with up to 8,600 \wn of vibrational energy. This comparison is based on the extensive knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision.}, 114301 (2009).} Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities for intramolecular vibrational redistribution (IVR) are first investigated for the $\nu 4+\nu 5$ and $\nu 3$ bright states, for $J=$ 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational $l-$type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor $\varphi d$, the IVR lifetime $\tau IVR$, and the recurrence time $\tau rec$. For the two bright states $\nu 3+2\nu 4$ and $7\nu 4$, the collisionless dynamics for thermally averaged rotational distributions at $T $= 27, 270 and 500 K were calculated from the available spectroscopic data. For the $7\nu 4$ bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states.