Spectroscopy is a method of analysis based on the wavelength or intensity of emission, absorption or scattering generated by the energy level transition of molecules when substances interact with radiant energy.
Spectroscopy It is a method of analysis based on measuring the wavelength and intensity of emission, absorption or scattering radiation generated by the transition between quantized energy levels in the substance when the substance acts with the radiant energy.
Spectroscopy can be divided into Atomic spectrometry and Molecular spectroscopy 。 Atomic spectrometry is a method of Outer or inner electron of atom It is produced by the change of energy level, and its manifestation is line spectrum. Those belonging to this type of analysis method are Atomic emission spectrometry （AES）、 Atomic absorption spectrometry （AAS）， Atomic fluorescence spectrometry (AFS) and X-ray fluorescence spectrometry (XFS), etc. Molecular spectroscopy is produced by the change of electronic energy level, vibration and rotation energy level in molecules, and is represented by band spectrum.
Such analysis methods include: ultraviolet visible Spectrophotometry （UV-Vis）， Infrared spectrometry (IR), molecular fluorescence spectroscopy (MFS), molecular phosphorescence spectroscopy (MPS), etc. 
