Vibrational dynamics of the C-O stretch vibrational in alcohols
We present a study on the vibrational dynamics of the CO stretch vibration of methanol and ethanol in carbon tetrachloride (CCl4) solution. The relaxation of the excited CO stretch vibration was observed to occur in two steps. In the first step energy is transferred from the v = 1 state of the CO stretch vibration to an intermediate state with a time constant of 3.2±0.2 ps for methanol and 3.2±0.7 ps for ethanol. The intermediate state is most likely formed by the n = 3 or 4 state of the COH bending mode, which is also known as the torsional mode. In the second step energy is transferred from this intermediate state to low-energy modes, leading to a full equilibration of the energy. In methanol this thermalization occurs with a time constant of 28±1ps. In ethanol the second step is faster, with a time constant of 12±2 ps.