What absorbs at 905 cm⁻¹ in an FTIR spectrum?
A band near 905 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 905 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 |
|---|---|---|---|
| Oxygen heterocycle | 3 | 3 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
| Imide | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Thiol | 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
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 905 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
“Explicit assignment: 'chain scission (905'”
Biodegradation of Unpretreated Low-Density Polyethylene (LDPE) by Stenotrophomonas sp. and Achromobacter sp., Isolated From Waste Dumpsite and Drilling Fluid DOI: 10.3389/fmicb.2020.603210 -
C-S single bond confidence 1.0
“The formation of C-S-H gel is denoted by a progressive shift in the O-Si-O stretching vibrations from 905 to cm-1 29Si 995 in the FTIR spectrum during 1 week.”
The Application of 29Si NMR Spectroscopy to the Analysis of Calcium Silicate-Based Cement using Biodentine™ as an Example DOI: 10.3390/jfb10020025 -
confidence 1.0
“S2 of the supplemented file, and the lattice of S1000 expands compared to S600 and S800, the peak at 905 K is related not to the oxygen absorption into the particle but to the oxygen redistribution from the absorbed oxygen to the”
Control of magnetic properties and band gap by Co/Mn ordering and oxygen distributions of La2CoMnO6 DOI: 10.1016/j.jmmm.2017.03.040 -
Oxygen heterocycle confidence 1.0
“LLM confirmed rule peak-group candidate”
Radzir 等 - 2015 - Effect of lithium bis(trifluoromethylsulfonyl)imid DOI: 10.1007/s10008-015-2910-z -
Amide confidence 1.0
“The weak to medium vibrational bands at 1045 and 1264cm-1 sharpandintensebandsat722,946,1154,1366,and1414cm-1 can be assigned to C-N stretching from 1200 to , 905cm-1 rocking from TETS/HEXS, and the shoulder at and CH2”
Dernaika 等 - 2014 - Spectroscopic Identification of Neurotoxin Tetrame DOI: 10.1155/2014/207258 -
Amine primary confidence 1.0
“cm(cid:0) C-O N-H 1 1130 (stretching C-OH in primary alcohol and stretching (corresponding to bending vibration in secondary amine and/or cm(cid:0) 1 -OH 1074-1061 - (secondary stretching), 905 from ester group), primary amine band in plane”
Functionalization of poly(glycidylmethacrylate) with iminodiacetate and imino phosphonate groups for enhanced sorption of neodymium - sorption performance and molecular modeling DOI: 10.1016/j.reactfunctpolym.2022.105389 -
Ring structure confidence 1.0
“The cm-1 absorption peak at 905 represents the vibration of C1-H group and the ring and is a characteristic peak of b-glucosidic bond of glucose.”
Hu 等 - 2021 - Pyrolytic Characteristics and Kinetics of Guanzhon DOI: 10.1016/j.fuel.2014.01.014 -
Alkene (C=C) confidence 1.0
“The band with the maximum at ~905 present in both oil samples cis-substituted can be attributed to the stretching vibrations of olefin groups, which may be additionally enhanced by the vibrations of the vinyl group.”
Comparative Analysis of Phytochemicals and Antioxidant Properties of Borage Oil (Borago officinalis L.) and Milk Thistle (Silybum marianum Gaertn) DOI: 10.3390/app13042560
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