Analysis of infrared spectroscopy

1. Starting from the high-frequency region (4000-1500cm-1), analyze and predict the possible functional groups in the sample, and then further verify them in conjunction with the fingerprint region (1500-400cm-1).

2. Generally, only 20% of the infrared spectrum belongs to localized vibrations, and only this part of the absorption peak can be fully attributed. Therefore, do not attempt to analyze every absorption band in the infrared spectrum;

3. Dig for more negative evidence, that is, information that does not have an absorption peak in a certain region may be more valuable than information that has an absorption peak, because there may be several sources of interference when a certain absorption band is generated in the infrared spectrum;

4. By comparing the differences in infrared spectra obtained from different sample preparation techniques, hydrogen bonds within or between molecules can be determined. The binding state of a typical sample in non-polar solvents and dilute solutions may differ, leading to changes in the stretching vibration frequency, deformation vibration frequency, and absorption peak shape of the group.