Question

What is IR data and what do the peaks mean?

Answer 1

IR data - Over time organic chemists have recorded and catalogued the types and locations of IR absorptions produced by a wide variety of chemical bonds in various chemical environments. These data can be quickly referenced through tables of IR absorption ranges and compared to the spectrum under consideration. As a general rule, the most important factors determining where a chemical bond will absorb are the bond order and the types of atoms joined by the bond. Conjugation and nearby atoms shift the frequency to a lesser degree. Therefore the same or similar functional groups in different molecules will typically absorb within the same, specific frequency ranges. Consequently tables of IR absorptions are arranged by functional group.

Peak Means - The size of the peak has two implications, one it is a measure of the oscillator strength of the transition involving the vibration and second, on a quantitative aspect the size of the peak , i.e the peak area is proportional to the concentration of the analyte which is responsible for the peak observed.