What absorbs at 1308 cm⁻¹ in an FTIR spectrum?
A band near 1308 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 1308 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 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Metal oxygen | 3 | 3 | 1.0 |
| Amide | 3 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Secondary amine | 2 | 1 | 1.0 |
| C n single bond | 2 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Urethane | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Oxalate | 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 |
|---|---|---|---|
| polyurethane | 1308, 2270, 1700 | Alkyl C-H, Methacrylate, Acetate | 1 |
| nanocomposite | 1308, 2921, 3300 | Alkyl C-H, Methacrylate, Acetate | 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 1308 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
-
Carbonyl (C=O) confidence 1.0
“A peak at 1730 cm-1 primarily due to observation of a new peak at 1308 stretching vibration of the C=O bond demonstrating the the C=O vibration of the carboxylate anion as the result presence of carboxylic acid.”
Hasanuddin 等 - 2020 - Physicochemical Characterization and Controlled Re DOI: 10.22146/ijc.40921 -
confidence 1.0
“Considering that Cr-supplemented sidered as basis for minimally invasive and nonanimals (CRE) showed higher band area in 1308 and cm21 destructive measuring systems, as the use of these 1396 bands than that of the non-supplemented instrumen”
Jeronimo 等 - 2012 - Detection of Creatine in Rat Muscle by FTIR Spectr DOI: 10.1007/s10439-012-0549-9 -
Metal oxygen confidence 1.0
“cm-1 oxalate.22,23 is from outer-sphere adsorbed peak at 1308 cm-1 The 1308 peak is initially more prominent due to influence surface charge and diminishes as the of the positive TiO 2 coordinated oxalate becomes more dominant, thereby redu”
Savory 等 - 2011 - Shallow Electron Trap, Interfacial Water, and Oute DOI: 10.1021/jp102723u -
Oxalate confidence 1.0
“Another proin the ATR-FTIR cell was best for the 13 µg cm-2 nounced feature is the oxalate band at 1308 cm-1, loading.”
Cychy 等 - 2021 - Optimizing the nickel boride layer thickness in a DOI: 10.1016/S1872-2067(20)63766-4 -
Alkyl C-H confidence 1.0
“Also, negative correlation peaks have been 𝑇 assigned to βPh(C-H) bands (at 1308, 1120, 1073 cm-1).”
Drzewicz 等 - 2020 - Vibrational Dynamics of a Chiral Smectic Liquid Cr DOI: 10.3390/cryst10080655 -
Acetate confidence 1.0
“Thus, CA and PCA indomethacin (spectrum g) are found at 3965.3 and 2926.6 cm-1 (O-H stretching vibration), 1717.0 data imply that co-crystals at 1:1 and 1:2 molar ratios are formed, while co-crystallization at 2:1 molar cm-1 (C=O stretching”
Garbacz 和 Wesolowski - 2018 - DSC, FTIR and Raman Spectroscopy Coupled with Mult DOI: 10.3390/molecules23092136 -
Metal oxygen confidence 1.0
“Bands at 1308 and 1348 denoted a combination of Zr-O and Zr-OH a cm-1 vibration bonds [40, 41].”
Halla Velazquez-Jimenez 等 - 2014 - Zirconium-Carbon Hybrid Sorbent for Removal of Flu DOI: 10.1021/es403929b. -
Urethane confidence 1.0
“1303~1308 cm-1 was assigned to a urethane C-O/C-O-C/C-C C-H twisting vibration, stretching vibration and C-H wagging vibration of ester”
Synthesis and Characterization of Inulin-Based Responsive Polyurethanes for Breast Cancer Applications DOI: 10.3390/polym12040865
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