Spectroscopy is the name for a group of analytical techniques used in chemistry to produces spectra of a chemical sample's properties. They include:

Mass Spectrometry

By ionising a sample and deflecting it through a magnetic field, a spectrum of the relative atomic masses and relative proportions of the ions in the sample can be created. This is a good tool for analysing simple compunds and determining purity, but is less capable of analysing large organic compounds, although protein mass spectrometers have been developed for sequencing proteins.

Infrared spectroscopy

This measures a sample's absorbance of infrared at over aspectrum of frequencies, from which information about the bonds in the sample, which resonate with infrared radiation, can be obtained. This is often used to analyse organic compounds, as different functional groups show up clearly on the spectrum.

Ultraviolet and visible spectroscopy

This measures the absorbtion spectrum of a sample to ultraviolet and visible light. The electron energy levels can be determined from this spectrum, as well as some of the bonding and interactions between atoms.

Nuclear magnetic resonance

This uses a strong magnetic field to cause hydrogen atoms to resonate, when excited with radio waves, producing a spectum of the frequencies of radio waves that cause the most resonance. NMR spectra can then be interpreted to find the stucture of the sample. This is possibly the most detailed way of analysing a sample and is usually used for large organic chemicals.