Types of spectroscopy

In this post, I discuss the types of spectroscopy and on what basis spectroscopy is divided.

       Spectroscopy is a branch of chemistry that deals with the interaction of light with matter.

 In other words, it is an analytical method for qualitative and quantitative estimation by use of light. Light is in the form of electromagnetic radiations which have a specific wavelength and energy.

Types 
 On the basis of electromagnetic radiations, spectroscopy is divided into many types.
 There are three main types which are further divided into many types.

a. Based on the level of study:-
       When we study at atomic and molecular levels then light passes through the sample changes the atomic and molecular levels. Here are two types

1) Atomic spectroscopy:
        In this spectroscopy, energy changes take place at atomic levels. it is further dived into two types.

•  Atomic absorption spectroscopy 
•  Atomic emission spectroscopy.

These are referred to as atomic absorption spectroscopy and flame photometry respectively.


2) Molecular spectroscopy:
            Here light brings changes at the molecular level. The characters like molecular absorption. emission and vibration are studied.

This is further divided into 

• UV-spectroscopy 
• Infrared spectroscopy 
• FTIR

B) Based on the property of either absorption or emission.

      Here changes bring on the basis of either electromagnetic radiation absorbed or emit through the sample. Here are two types.


1) Absorption spectroscopy:
    Here absorption takes place by the sample. The extent of absorption and the wavelength of the absorbed light is considered. 

• The wavelength of light absorbed tells the nature of the compound. 
• The intensity of absorbed light tells the concentration.

The types of spectroscopic methods coming under this method are: 

• UV-spectroscopy 
• infrared spectroscopy 
• Nuclear magnetic resonance (NMR) 

2) Emission spectroscopy:
     Here we study the emitted light from the sample. This absorption of light leads to the transition of electrons from the ground state to an excited state. These excited electrons return back to the ground state by the release of electromagnetic radiation (light) of a specific wavelength. 

• The intensity gives the concentration.
•  The wavelength tells the nature of the compound.

    Types include 

• fluorimetry 
• flame photometry

C) Based on the level of study i.e. electronic or magnetic levels.

            Here the study is done based on the electronic or magnetic properties of the compound. Light is electromagnetic radiation. That is it has both electronic and magnetic properties.

Here are two types.

Electronic spectroscopy:
    When analysis of compound is carried out without the magnetic field then it is known as electronic spectroscopy.

Examples of this method are again colorimetry, UV-spectroscopy, IR, fluorimetry, etc.

Magnetic spectroscopy:

     Here the substance is exposed to electromagnetic radiation in presence of an external magnetic field and the absence of an electric field.

Examples include Nuclear magnetic resonance spectroscopy (NMR), Electron spin resonance spectroscopy (ESR).