Molecular Spectroscopy

Up to now we have only been discussing how atoms emit electromagnetic energy. Molecules operate in much the same way, but are slightly more complicated. We have described an atom becoming charged as a change in electron distribution. Molecules can change the electron distribution as well, but they can also vibrate and rotate. A molecule can change electron distribution, vibrate, or rotate when it receives a specific amount of energy, such as when it absorbs a particular frequency of electromagnetic radiation.

When a molecule absorbs a particular frequency and changes electron distribution, vibrates, or rotates, it will eventually relax. When it relaxes, it will release the energy it absorbed in the form of electromagnetic radiation. Due to this, we can still use absorption and emission spectra to identify the presence of particular molecules.

Go on to Activity #3: Remote Sensing


Electromagnetic Radiation | Electromagnetic Frequency | Light | Generating Electromagnetic Radiation | Sources of Electromagnetic Radiation | Reflection and Absorption | Atomic Spectroscopy | Molecular Spectrscopy