In this module we introduce the theory underpinning infrared (IR) spectroscopy and show examples of analysis using the technique. Transitions between the vibrational energy levels of molecules occurs in the infrared region of the electromagnetic spectrum. We start with the theory underlying vibration using the simple harmonic oscillator model. Analysis of more complex molecules is introduced using group frequencies and number of vibrational modes. You will also be shown how to obtain an infrared spectrum and will have an opportunity to run your own spectrum. At the end of this module you are given a link to view how to obtain an infra red spectrum in the laboratory. Don't forget to complete the end of week laboratory quiz which contributes to your final mark for this course.