ftir分析方法（FTIR analysis method）.docVIP

ftir分析方法（FTIR analysis method） Two, group frequency and characteristic absorption peak Each molecule of the constituent molecule has its specific infrared absorption region. According to the nature of chemical bond, which can be divided into four regions: 4000 - 2500 cm-1 - 2000 cm-1 2500 hydrogen bonded area; 2000 - 1500 cm-1 and keypad; double bond zone; 1500 - 1000 cm-1 bond zone. According to the absorption characteristics, it can be divided into functional areas (4000 - 1300cm-1) and fingerprint areas (1300 - 600cm-1). The characteristic absorption peak of the group usually appears in the functional group, and the absorption peak is sparse, which is beneficial to the analysis, and is the most useful area for the identification of the group. The latter mainly contains spectra produced by deformation vibration. When the molecular structure is slightly different, the absorption peaks show subtle differences in this region, thus being as specific as human fingerprints. This region is important for distinguishing compounds with similar structures. Three 、 infrared absorption spectrum analysis A typical infrared spectrum is shown: In order to facilitate the analysis of infrared spectrum, the spectrum is usually divided into eight different sections. According to the corresponding absorption peaks, the possible structure of the compounds can be deduced. A) O-H and N-H stretching vibration zone (3750-3000 cm-1) Alcohol, phenol, acid in nonpolar solvents, small concentration (dilute solution), the sharp peak of strong absorption; when the concentration is high, the association effect, wide peak. The peak intensity of amino compounds is weaker than that of associated OH base, and the peaks are more sharp. The number of absorption peaks depends on the number of substituents on the N atom. The primary amine and the primary amide are Shuangfeng, and the intensity of the two peaks is approximately equal. B) C-H stretching vibration zone (3300 - 2700cm-1) The stretching vibra