What absorbs at 1160 cm⁻¹ in an FTIR spectrum?
A band near 1160 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 1160 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 | 56 | 55 | 1.0 |
| Methacrylate | 54 | 53 | 1.0 |
| Acetate | 53 | 52 | 1.0 |
| Methoxy (OCH3) | 52 | 51 | 1.0 |
| Alkyl C-H | 17 | 15 | 1.0 |
| Carbohydrate | 10 | 10 | 1.0 |
| Hydroxyl (O-H) | 10 | 10 | 1.0 |
| Amide | 8 | 7 | 1.0 |
| Secondary amine | 7 | 6 | 1.0 |
| C c single bond | 6 | 6 | 1.0 |
| Carbonyl (C=O) | 5 | 5 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| Silicon-oxygen (Si-O) | 4 | 4 | 1.0 |
| Phosphate (PO4) | 4 | 4 | 1.0 |
| C n single bond | 4 | 3 | 1.0 |
| N h | 4 | 3 | 1.0 |
| Ring structure | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Ketone | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Silicon (Si) | 3 | 3 | 1.0 |
| Lipid | 3 | 3 | 1.0 |
| Aldehyde (CHO) | 3 | 3 | 0.9 |
| Alkene (C=C) | 3 | 2 | 1.0 |
| Thiocarbonyl | 2 | 2 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| Metal oxygen | 2 | 2 | 1.0 |
| C-S single bond | 2 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Phenolic | 1 | 1 | 0.8 |
| S eq o | 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 |
|---|---|---|---|
| cellulose | 1160, 1735, 1650 | Acetate, Methacrylate, C-O single bond | 1 |
| starch | 1160, 1650, 1540 | Methacrylate, Acetate, C-O single bond | 1 |
| microplastics | 1160, 1643, 1614 | 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 1160 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
“cm-1: specified as follows: 1440 O-H plane bending, 1420 C-H plane deformation in cm-1: cm-1: cm-1: lignin, 1370 -C-H bending in wood, 1320 C-O syringyl ring and CH wagging, 1240 con2 cm-1: jugated ketone (phenyl-carbonyl) in lignin, 1160 C”
Physicochemical characterisation of barley straw treated with sodium hydroxide or urea and its digestibility and in vitro fermentability in ruminants DOI: 10.1038/s41598-022-24738-w -
Borate confidence 1.0
“matrix.7,14 advancement of the charred layer further into the structure.53 G-mode peak represents the normal graphite However,theB-OstretchingcausedbyO-B-Ostretching,which cm(cid:3)1 cm(cid:3)1 4.3 Compositional analysis by FT-IR spectrosco”
Reticulated three-dimensional network ablative composites for heat shields in thermal protection systems DOI: 10.1039/c4ra05811a -
Alkyl C-H confidence 1.0
“cm-1 cm-1 cm-1 stretching), 2894 (aliphatic C-H stretching), 1160 (bridge O stretching), 1050 (C-O stretching), also the usual characteristic pattern of cellulose can be seen in the fingerprint region.”
Surface modification of bacterial cellulose membrane by oxygen plasma treatment DOI: 10.1016/j.surfcoat.2016.06.035 -
Acetate confidence 1.0
“The region at 1000-1200 is 1160cm-1), attributed to the stretching vibration absorptions of the C-O (around indicating different C-O-containing degradation products but may also indicate phosphate ions, bonds of the glycosidic linkages [52]”
Campanale 等 - 2023 - Fourier Transform Infrared Spectroscopy to Assess DOI: 10.3390/polym15040911 -
Alkyl C-H confidence 1.0
“3 2 3asymmetric and symmetric vibrations of CF 3SO [5] 1250 1249 1251 1253 1250 SO 3 C-H BMIM+ and symmetric stretching mode of CF 1160 1168 1166 1166 1167 vibrational mode for cyclic”
Effects of ionic liquid on the hydroxylpropylmethyl cellulose (HPMC) solid polymer electrolyte DOI: 10.1007/s11581-016-1768-0 -
Acetate confidence 1.0
“The absorption peak at 1160 could be attributed to the C-O cm-1 bending vibration [38].”
Gani 等 - 2017 - Physico-chemical, structural, pasting and thermal DOI: 10.1016/j.ijbiomac.2016.10.100 -
C-S single bond confidence 1.0
“The bands at 1160 and 1053 reductive desorption characteristics for both aerial and electroN-N C-S are assigned to and stretching frequencies,”
Kalimuthu 等 - 2009 - Leaflike Structured Multilayer Assembly of Dimerca DOI: 10.1021/jp810337s -
Acetate confidence 1.0
“The absorption band at cm-1 1735 could be attributed to C=O vibrations in DAS, while the weak peak at cm-1 1160 was caused by C-O bond stretching of C-OH group in glucan residues.”
Synthesis of a Magnetic Nanoparticles/Dialdehyde Starch‐based Composite Film for Food Packaging DOI: 10.1002/star.201800035
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