Vibrational energy relaxation dynamics of diatomic molecules inside superfluid helium nanodroplets. The case of the I2 molecule
Vibrational energy relaxation dynamics of diatomic molecules inside superfluid helium nanodroplets. The case of the I2 molecule
A. Vilà, M. Paniagua, M. González.
Phys. Chem. Chem. Phys. doi: 10.1039/c7cp05694j
Time evolution of the vibrational populations for the initial excitation of the I2 molecule to v=3.
The vibrational energy relaxation (VER) of a X2 molecule in a 4He superfluid nanodroplet (HeND; T = 0.37 K) was studied adapting a hybrid quantum approach proposed by us. In the first application the I2 molecule was examined and this corresponds to the first theoretical investigation on VER of molecules embedded in HeND. The global relaxation from the initial excited state v down to the ground state (v = 0) happens in the ns scale and VER occurs following a cascade mechanism, where an arbitrary relaxation, e.g., v-1 → v-2, can only occur once the previous one has taken place. This mechanism was understood once the values of the coupling matrix elements were analyzed, and the time evolution of the populations of two consecutive vibrational levels was adequately described using a non-linear two-state Hamiltonian model. We hope that this first theoretical work on molecular VER dynamics in HeND will encourage researchers to investigate this important process about which we still know very little.