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Use this tag for questions about spectroscopic methods in practice and in theory, especially where more specific tags for the individual method (such as [nmr-spectroscopy] or [ir-spectroscopy]) are not available.

Spectroscopy is the study of the interactions between matter and radiated energy. Experimentally, the results are returned as a function of wavelength versus amplitude (intensity), where the spectral lines represent the resonance frequency of the sample.

There are many different types of spectroscopy. Common spectroscopy techniques include:

to name a few.

Spectroscopic techniques are often used in chemistry to characterize a compound and determine its constituents. In biochemistry, spectroscopy is often used to study the conformers and physical structure of proteins and other biological molecules.

A subset of these topics is time-resolved spectroscopy, which uses ultra-fast laser pulses (on the pico or femtosecond timescale) to analyze transient species as they are forming. Time-averaged spectroscopy, such as an FT-IR encountered in an organic lab, provides an average IR spectrum of all the molecules in your sample, whereas ultra-fast spectroscopy can provide information on the structures of intermediates and even very short-lived transition states as a reaction proceeds along its reaction coordinate. Whilst transient UV/vis and IR spectroscopy is common, ultra-fast NMR is not possible due to the relative longevity of the beta state.