fluoresenssivärähtelyään

Fluoresenssivärähtelyään, a Finnish term, translates to "fluorescence vibration" or "fluorescence oscillation" in English. This phenomenon describes the dynamic changes in the vibrational states of a molecule during or immediately after the process of fluorescence. When a molecule absorbs a photon and is excited to a higher electronic state, it often also gains vibrational energy. As it then relaxes back to a lower electronic state and emits a photon to fluoresce, the molecule's vibrational energy can change. This change in vibrational energy is what "fluoresenssivärähtelyään" refers to.

The emitted fluorescence photon typically has less energy than the absorbed photon, meaning it has a longer wavelength. This energy difference accounts for the relaxation from the excited electronic state to a lower vibrational level within that excited state before emission, and then relaxation to various vibrational levels of the ground electronic state after emission. The specific vibrational modes that are excited or de-excited during this process contribute to the vibrational structure observed in fluorescence spectra. Studying these fluorescence vibrations can provide valuable insights into molecular structure, dynamics, and interactions. Techniques like time-resolved spectroscopy are often employed to observe and analyze these rapid vibrational changes. The term emphasizes the coupled nature of electronic and vibrational transitions in the process of fluorescence.