What absorbs at 1387 cm⁻¹ in an FTIR spectrum?
A band near 1387 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 1387 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 |
|---|---|---|---|
| Alkyl C-H | 6 | 6 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Carbon dioxide | 2 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Nitrate | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 0.9 |
| Ammonium | 1 | 1 | 0.9 |
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 |
|---|---|---|---|
| PMMA | 1387, 1722, 1383 | Methacrylate, Alkyl C-H, Methoxy (OCH3) | 2 |
| AgNPs | 1387, 1232, 1048 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
| ZnO nanoparticles | 1387, 1219, 1726 | Alkyl C-H, Methacrylate, C-O single bond | 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 1387 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
-
Carbon dioxide confidence 1.0
“Figure 5 depicts the temperature stability of the adsorbed species, cm-1 sample is heated above 500 K, the peaks at 1387 and 1362 desorption of carbon dioxide, and peak area of the adsorbed have disappeared and two new peaks appear at 1400”
Durand 等 - 2010 - Reaction of Formic Acid over Amorphous Manganese O DOI: 10.1021/jp104629j -
C c single bond confidence 1.0
“1260.39 C-C-O stretching 1386.72 1392 1393.47 O-CH deformation 3”
Ganesan 等 - 2018 - The effect of titanium dioxide nano-filler on the DOI: 10.1007/s10854-018-8815-8 -
Metal oxygen confidence 1.0
“cm-1 Alkaline treatment by adding NaOH 10 M shows a new peak at 1387 (5% of intensity) that is proposed for Al-O-Al vibration.”
Mutrofin 等 - 2018 - Physical-chemistry of Nawangan's phyropyllite and DOI: 10.1088/1757-899X/285/1/012026 -
confidence 1.0
“A very sharp absorption band at 1387 NH+ could be due to the N-H stretching vibration in ion.”
Parida 等 - 2004 - Studies on manganese-nodule leached residues - 1. DOI: 10.1016/j.jcis.2004.04.057 -
Carbon dioxide confidence 1.0
“the vibration identified as ν(C-H) is found in SERS spectrum in a less intense band at 981 Despite the similarity of SERS signal acquired for neutral and deprotonated state of artepillin C, some particularity was observed when the carbonyl”
EXPRESS: Vibrational Spectroscopic Characterization and Coherent Anti-Stokes Raman Spectroscopy (CARS) Imaging of Artepillin C DOI: 10.1177/0003702820904456 -
Nitrate confidence 1.0
“LLM confirmed rule peak-group candidate”
Carrier mechanism of ZnO nanoparticles-embedded PMMA nanocomposite organic bistable memory device DOI: 10.1016/j.solidstatesciences.2019.106046 -
Acetate confidence 1.0
“following peaks 3385 cm-1 (for hydroxyls [50]), 2996 cm-1 (for stretching vibration (O)CH3 cm-1 cm-1 found in propolis components [51,52], 2894 for the saturated CH stretches), 1644 that found in propolis components [51,52], 2894 cm-1 for t”
The Synergistic Effect of Biosynthesized Silver Nanoparticles and Phage ZCSE2 as a Novel Approach to Combat Multidrug-Resistant Salmonella enterica DOI: 10.3390/antibiotics -
confidence 1.0
“Peaks appearing at 1600 and 1387 cm-1 were assigned to the symmetric and asymmetric Zn.69 C-O stretching of bonded to Another peak at 1660 cm-1 C�O was referred to the stretching vibration of the acid.70 group of terephthalic The peaks fall”
Ionic Liquid Functionalized Metal–Organic Framework ([DEIm][PF6]@MOF-5): Synthesis, Characterization, and Catalytic Application in the Reduction of 4-Nitrophenol DOI: 10.1021/acsomega.2c05808
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