How does fluorescence spectroscopy identify compounds?

Fluorescence spectroscopy identifies compounds by detecting the unique light emission patterns when they are excited by light.

Fluorescence spectroscopy is a type of spectroscopy that uses the phenomenon of fluorescence to identify and quantify the presence of specific compounds. When a compound absorbs light of a certain wavelength, it gets excited to a higher energy state. As it returns to its ground state, it emits light of a different wavelength. This emitted light is what we refer to as fluorescence.

Each compound has a unique pattern of absorbing and emitting light, known as its fluorescence spectrum. This is due to the specific energy levels of the electrons in the compound's atoms. By analysing this spectrum, we can identify the compound. The intensity of the fluorescence can also give us information about the concentration of the compound in a sample.

The process begins by shining a light, usually ultraviolet or visible light, onto the sample. The compounds in the sample absorb this light and get excited to a higher energy state. After a very short time, typically a few nanoseconds, the compounds return to their ground state and emit light at a longer wavelength. This emitted light is collected and analysed by a detector.

The detector records the intensity of the light at different wavelengths, creating a fluorescence spectrum. This spectrum is then compared to known spectra of various compounds to identify the compounds present in the sample. The intensity of the fluorescence at specific wavelengths can also be used to determine the concentration of the compounds.

Fluorescence spectroscopy is a powerful tool in many fields, including chemistry, biology, and medicine. It can be used to identify and quantify a wide range of compounds, from small organic molecules to large biological macromolecules. It is also a non-destructive technique, meaning the sample is not altered or destroyed during the analysis. This makes it particularly useful for studying sensitive or valuable samples.