When operating an infrared spectroscopy analysis in a laboratory, we refer to the interaction of infrared light with matter via absorption, emission or reflection. The goal of this analytical technique is toidentify the functional groupsin a sample via the interpretation of a spectrum. If we consider light a wave, this technique focuses on the principle that different functional groups absorb the radiation at different wavelength values, depending on the structure of the molecules in the sample. Infrared is considered vibrational spectroscopy, as the energy connected to this radiation is not strong enough to break chemical bonds, but produces a vibration with a change indipole moment。The dipole moment can be described as uneven distribution of electron density in heteronuclear molecules and changes with the expansion and contraction of a bond. When there is a change in dipole moment, the molecule can be consideredIR active。样品吸收光从源时,the bonds vibrate in a stretching or bending mode, producing signals that are represented in the spectrum.