What absorbs at 770 cm⁻¹ in an FTIR spectrum?
A band near 770 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 770 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 |
|---|---|---|---|
| C-O single bond | 4 | 4 | 1.0 |
| Metal oxygen | 4 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Silicon carbon | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Urethane | 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 |
|---|---|---|---|
| TiO2 | 770, 1700, 1093 | Metal oxygen, Alkyl C-H, C-O single bond | 1 |
| polyurethane | 770, 2270, 1700 | Alkyl C-H, C-O single bond | 1 |
| composite | 770, 1703, 1295 | Alkyl C-H, C-O single bond, Aromatic ring | 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 770 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
-
confidence 1.0
“O-O the shoulder at 770 can be assigned to the stretching support to the latter "nucleophilic attack mechanism", as Ti-18O-18O-Ti.”
Nakamura 和 Nakato - 2004 - Primary intermediates of oxygen photoevolution rea DOI: 10.1021/ja0388764CCC -
Hydroxyl (O-H) confidence 1.0
“Obtained Wavenumber Reference Wavenumber Functional Group/Fingerprint ObtainedWavenumber ReferenceWavenumber FunctionalGroup/Fingerprint cm-1 cm-1 2965.11 ±3000 (Strong & Board) -COOH (O-H Stretching) 2965.11cm-1 ±3000cm-1 -COOH(O-HStretchi”
Validation of the Developed Zero-Order Infrared Spectrophotometry Method for Qualitative and Quantitative Analyses of Tranexamic Acid in Marketed Tablets DOI: 10.3390/molecules26226985 -
Acetate confidence 1.0
“The vibration peak at ~770 is due to the O = C-O deformation [20], while cm-1 the vibration peak at ~1342 is due to the C-H bending vibrations of formate ions (HCOO-)”
Proton-Conducting Biopolymer Electrolytes Based on Carboxymethyl Cellulose Doped with Ammonium Formate DOI: 10.3390/polym14153019 -
Alkyl C-H confidence 1.0
“Technora displays extra peaks due to the 3-4' POP cm-1 sequences: the peak located at ~1264 is related to the C-O vibration of the ether cm-1 function, and the peak at ~770 is related to C-H deformation of meta-substituted aromatic rings [4”
Derombise 等 - 2009 - Degradation of Technora aramid fibres in alkaline DOI: 10.1016/j.polymdegradstab.2009.07.021 -
Acetate confidence 1.0
“Technora displays extra peaks due to the 3-4' POP sequences: the peak cm-1 cm-1 located at ~1264 is related to the C-O vibration of the ether function, and the peak at ~770 is”
Influence of finish treatment on the durability of aramid fibers aged under an alkaline environment DOI: 10.1002/app.31534 -
Urethane confidence 1.0
“The peak at 770 is attributed to the bending vibration peak in vibration peak in the carbamate formed by the reaction.”
The Effect of Glycidyl Azide Polymer Grafted Tetrafunctional Isocyanate on Polytriazole Polyethylene Oxide-Tetrahydrofuran Elastomer and its Propellant Properties DOI: 10.3390/polym12020278 -
Acetate confidence 1.0
“The presence of sharp peaks at 1221, 1104, 770 cm-1 denotes the C-O C-Ostretchingcorrespondingtoalcoholgroups[18,19].”
Manufacturing and Characterization of Novel Electrospun Composite Comprising Polyurethane and Mustard Oil Scaffold with Enhanced Blood Compatibility DOI: 10.3390/polym9050163 -
C-O single bond confidence 1.0
“For the HSPC spectrum, the band at 717 was ascribed to the cm-1 O-C-C-N+ stretch of the skeleton in the gauche conformation, and the band at 770 cm-1 O-C-C-N+ v(C-N) trans-conformation was caused by stretch of in the [52].”
Mechanism Study on Nanoparticle Negative Surface Charge Modification by Ascorbyl Palmitate and Its Improvement of Tumor Targeting Ability DOI: 10.3390/molecules27144408
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