What absorbs at 1393 cm⁻¹ in an FTIR spectrum?
A band near 1393 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 1393 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 |
|---|---|---|---|
| Amide | 5 | 5 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Secondary amine | 4 | 4 | 1.0 |
| C n single bond | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Bromine | 1 | 1 | 1.0 |
| Lewis acid site | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 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 |
|---|---|---|---|
| chitosan | 1393, 1650, 1655 | Alkyl C-H, Amide | 2 |
| zinc oxide | 1393, 1627, 1638 | Alkyl C-H, Amide | 1 |
| ZnO | 1393, 1400, 3430 | Alkyl C-H, Amide | 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 1393 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
-
Alkyl C-H confidence 1.0
“The band at 1,098 is G 1307 Ethyl undecanoate Coconut, cognac due to the methylene rocking vibrations overlapping the H 1393 Isobornyl propionate Fruit, turpentene out-of-plane bending vibration of cis-disubstituted olefins”
Mansor 等 - 2011 - Application of Fast Gas Chromatography and Fourier DOI: 10.1007/s12161-010-9176-y -
Acetate confidence 1.0
“increasedfrom300to500,700and900◦ C,onlyabroadbandof The peaks at 1683 and 1624 represents the C O and C O in 448cm-1, 1393cm-1 zinc oxide was observed (460, 465 and respectively) the spectrum [17].”
Wahab 等 - 2008 - Synthesis and characterization of hydrozincite and DOI: 10.1016/j.jallcom.2007.07.029 -
Amide confidence 1.0
“LLM confirmed rule peak-group candidate”
Influence of the Enzymatic Hydrolysis Using Flavourzyme Enzyme on Functional, Secondary Structure, and Antioxidant Characteristics of Protein Hydrolysates Produced from Bighead Carp (Hypophthalmichthys nobilis) DOI: 10.3390/molecules28020519 -
Amide confidence 1.0
“1267 1270 Bend ip N-C-H 1284 1277 1347 1350 Stretch sym C-N 1393 1403 1390 1395 Stretch asym C-N 1510 1513 1566 1578 Stretch sym C-C-C pyrazolic aCalculatedfrequenciesabove600cm-1 arescaledbyafactorof0.975.”
Albanese 等 - 2012 - Theoretical and experimental characterization of p DOI: 10.1039/C2JM34079H -
Carboxyl (COOH) confidence 1.0
“The absorption bands at 1580 and cm-1 C═C 1393 are attributed to the stretching and the symmetrical -COO stretching of”
Aloe Vera extract-based composite nanofibers for wound dressing applications DOI: 10.1016/j.msec.2021.112061 -
Amide confidence 1.0
“cm-1, cm-1, cm-1, band at 1645 C-H bending at 1393 C-N band at 1280 C-O stretching at band at 1645 cm-1, C-H bending at 1393 cm-1, C-N band at 1280 cm-1, C-O stretching at cm-1 cm-1.”
Bharathi 等 - 2023 - Facile Synthesis and Characterization of Chitosan DOI: 10.3390/polym15122700 -
Alkyl C-H confidence 1.0
“In the IR spectrum of adsorbed CPE, a band appeared at 1393 which 3 cm-1, is characteristic of C-H bending, and peaks at 1059 and 963 which correspond to C-O and P-O stretching, respectively, also appeared.”
Robust Magnetic -Fe2O3/Al–ZnO Adsorbent for Chlorpyriphos Removal in Water DOI: 10.3390/w14071160 -
C-S single bond confidence 1.0
“1 3 Journal of Nanostructure in Chemistry (2019) 9:77-93 85 cm-1 1393 and a prominent peak of C-S of DTC group 2.5 cm-1 was observed at 1065 (Fig.”
Applications of copper nanoparticles for colorimetric detection of dithiocarbamate pesticides DOI: 10.1007/s40097-019-0299-4
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.