How does IR spectroscopy work?

Hint Principle of IR spectroscopy is based on the emission, reflection and mainly on the absorption of infrared light due to which a couple of vibrations regenerate inside the molecule by the absorption of energy from light.

Complete step by step solution:
IR spectroscopy stands for Infrared spectroscopy and sometimes also by the name of vibrational spectroscopy. Some important points regarding this spectroscopy are as follow:
Working of IR spectroscopy:
-When we fall IR radiations to any molecule the molecule absorbs that radiations and after absorption there is a rotational and transitional vibrations occur inside the molecule.
-Energy of IR radiation is not so much that they will produce electronic transitions inside the molecule.
-Doe to this absorption of light there are mainly two types of vibrations observed in the molecule and that vibrations are stretching and bending and because of this absorption molecule will show IR spectrum.
-Wavelength range of IR spectrum is from $ 2,500 $ to $ \text{16,000nm} $ and frequency range is from $ 1.9\times {{10}^{13}} $ to $ \text{1}\text{.2 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{14}}}\text{Hz} $ .
-And for the above whole process an instrument is required which is known as IR spectrometer and in this instrument photo conducting detectors are present in which IR spectrum gets detected.
Uses of IR spectroscopy:
-By the use of IR spectroscopy structure of the subjected molecule can be detected.
-Rather than structure, which functional group is present in the molecule is also determined by the use of this spectroscopy because every group has its characterized vibrational frequency value.

Note: Here some of you may think that IR spectroscopy and electronic spectroscopy delivers the same thing but that is not true, because in electronic spectroscopy x – rays are used not infrared rays.