What absorbs at 1397 cm⁻¹ in an FTIR spectrum?
A band near 1397 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 1397 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Carbonate | 2 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Lipid | 1 | 0 | 1.0 |
| N n bond | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| ZnO | 1397, 1400, 3430 | Alkyl C-H, Acetate, Methacrylate | 1 |
| nanoparticles | 1397, 1732, 1647 | Alkyl C-H, C-O single bond, Methacrylate | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
Spectrum logic
This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 1397 cm⁻¹ is usually not enough for material identification by itself.
Real-world usage
This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.
Common mistakes
- Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
- Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
- Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.
Verification advice
When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.
Literature behind these assignments
-
Acetate confidence 1.0
“90 cm-1 peaks at 1547 and 1502 represents the C O and loss cm-1 spectrum.28 C O in the The IR bands at 1397 Weight 85 group.28 is assigned to the carbonate The bands correcm-1 (cid:6) sponding to stretching frequency centered at 1050”
Hadia 等 - 2014 - Effect of the Temperature on Structural and Optica DOI: 10.1166/jnn.2014.8861 -
Aromatic ring confidence 1.0
“Materials Science in Semiconductor Processing 96 (2019) 104-115 1397cm-1 are assigned to the C˭C vibration in aromatic ring and”
Effect of co-sensitization in solar exfoliated TiO2 functionalized rGO photoanode for dye-sensitized solar cell applications DOI: 10.1016/j.mssp.2019.02.027 -
C-O single bond confidence 1.0
“There were significant differences in the absorption band areas of the bands located in cm-1 cm-1 cm-1 the regions of 1087 (C-OH stretching), 1397 (CH from proteins and lipids), 1543 3 cm-1”
Mostaco-Guidolin 等 - 2010 - Molecular and chemical characterization by Fourier DOI: 10.3233/SPE-2010-0466 -
Carboxyl (COOH) confidence 1.0
“The results of TLC analysis indicated that purified EPSs cm-1, A peak at 1397 which is due to the carboxyl L.”
Optimization of food-grade medium for co-production of bioactive substances by Lactobacillus acidophilus LA-5 for explaining pharmabiotic mechanisms of probiotic DOI: 10.1007/s13197-020-04894-5 -
confidence 1.0
“ber 1396.84 Similarly, N-H stretch of amide in PA solid state interactions between PA and IB, and partial disIB.28 cm-1 The details of % crystallinity at 3162.69 was also shifted to higher wave number.”
Bhandari 等 - 2018 - Co-Amorphization of Ibuprofen by Paracetamol for I DOI: 10.17344/acsi.2017.3822 -
Amide confidence 1.0
“Comparing the three infrared spectra in Figure 2A, the newly generated peak at 1397 is the cm-1 stretching vibration peak of the C-N-C bond and the peak at 1167 is the stretching vibration peak of the C-N in the amide bond (curve c in Figur”
Inhibition of Poly(ethylenediaminetetraacetic acid-diethanolamine) on Deposition of Calcium Sulfate Crystal in Simulated Industrial Water DOI: 10.3390/cryst10060544 -
Alkyl C-H confidence 1.0
“N-H 725 bending vibration 1371 CH bending vibration 1397 CH bending vibration 2 2”
Cheng 等 - 2022 - Development of a High-Strength and Adhesive Polyac DOI: 10.1021/acsomega.1c06626 -
Alkyl C-H confidence 1.0
“The peaks at 1397 and 1017 were attributed to the characteristic absorption bands of the CH groups.”
Du 等 - 2020 - Synthesis, Property and Mechanism Analysis of a No DOI: 10.3390/min10020128
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