Annealing refers to a process of heating a material to a high temperature and then slowly cooling it
down. This process can have various effects on the properties of the material, including its
absorption peak in the infrared (IR) spectrum.
When a material is annealed, it can undergo various changes in its structure and composition, such
as the rearrangement of atoms and the removal of impurities. These changes can affect the
vibrational modes of the material, which determine its absorption peak in the IR spectrum.
In general, annealing can lead to a shift in the absorption peak towards the IR region. This shift
occurs because annealing can cause a decrease in the bond strength of the material, which results in
weaker bonds and lower vibrational frequencies. As a result, the absorption peak shifts towards
longer wavelengths (lower wavenumbers) in the IR region.
The exact nature and magnitude of the shift depend on various factors, such as the composition and
structure of the material, the annealing temperature and duration, and the specific vibrational
modes that are affected. Therefore, the absorption peak may not always shift towards the IR region
after annealing, and the effect may vary depending on the specific material and conditions.