Watching vibrational energy transfer in liquids with atomic spatial resolution

Ultrafast spectroscopy was used to study vibrational energy transfer between vibrational reporter groups on different parts of a molecule in a liquid. When OH stretching vibrations of different alcohols were excited by mid-infrared laser pulses, vibrational energy was observed to move through intervening CH₂ or CH groups, taking steps up and down in energy ending up at terminal CH₃ groups. For each additional CH₂, group in the path between OH and CH³, the time for vibrational energy transfer increased by about 0.4 picosecond.