What absorbs at 900 cm⁻¹ in an FTIR spectrum?
A band near 900 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 900 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 |
|---|---|---|---|
| Alkyl C-H | 28 | 28 | 1.0 |
| C-O single bond | 25 | 23 | 1.0 |
| Methacrylate | 23 | 22 | 1.0 |
| Acetate | 22 | 21 | 1.0 |
| Methoxy (OCH3) | 21 | 20 | 1.0 |
| Carbohydrate | 20 | 16 | 1.0 |
| Hydroxyl (O-H) | 19 | 18 | 1.0 |
| Silicon-oxygen (Si-O) | 14 | 13 | 1.0 |
| Aromatic ring | 11 | 10 | 1.0 |
| Silicon (Si) | 10 | 10 | 1.0 |
| Amide | 10 | 8 | 1.0 |
| C c single bond | 8 | 8 | 1.0 |
| Metal oxygen | 7 | 7 | 1.0 |
| Ring structure | 7 | 7 | 1.0 |
| Phosphate (PO4) | 6 | 6 | 1.0 |
| Siloxane (Si-O-Si) | 4 | 4 | 1.0 |
| Alkene (C=C) | 4 | 4 | 1.0 |
| Secondary amine | 4 | 4 | 1.0 |
| N h | 4 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Silanol (Si-OH) | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| Hydrogen bond | 3 | 3 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Silicate | 2 | 2 | 1.0 |
| Carbonate | 2 | 2 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| N n bond | 1 | 1 | 1.0 |
| Carbon dioxide | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| Perchlorate | 1 | 1 | 1.0 |
| Oxygen heterocycle | 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 |
|---|---|---|---|
| Silica | 900, 1100, 1080 | Alkyl C-H, Methacrylate, Acetate | 1 |
| silica nanoparticles | 900, 1718, 2925 | Alkyl C-H, Methacrylate | 1 |
| ionic liquids | 900, 938, 1040 | Alkyl C-H | 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 900 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
-
Carbohydrate confidence 1.0
“Peaksbetween900and wereassignedtothe & from the spectra before and after UV irradiation treatment (Bhat C2 carbon of pyranose ring and amino group, respectively”
Spectroscopic analyses of the influence of electron beam irradiation doses on mechanical, transport properties and microstructure of chitosan-fish gelatin blend films DOI: 10.1016/j.foodhyd.2014.09.038 -
confidence 1.0
“The weak bands at 900 and 949 are possibly stretching vibrations Si-O-Si.”
Biosynthesized Silica Nanosuspension as Thermal Fluid in Parabolic Solar Panels DOI: 10.3390/e23020142 -
Ring structure confidence 1.0
“spectra for the unirradiated ILs show a group of bands appearing 900cm(cid:2)1 between 500 and mainly attributed to the ring bending This work extends our previous studies on [emim][Tf 2N] and modes of the imidazolium cations and another gr”
Gamma and heavy ion radiolysis of ionic liquids: A comparative study DOI: 10.1016/j.jnucmat.2014.06.056 -
Hydroxyl (O-H) confidence 1.0
“4 cm(cid:3)1 bands of poldervaartite at 900 and 917 with a low intensity shoulderat907cm(cid:3)1areattributedtotheantisymmetricvibrations of the SiO 3(OH) units.”
Frost 等 - 2015 - Vibrational spectroscopic study of poldervaartite DOI: 10.1016/j.saa.2014.09.017 -
Perchlorate confidence 1.0
“The 4) and EC solution, considerable a lithium perchlorate (LiClO cm-1 gel exhibits predominantly ionic nature and a 0.67 of appear corresponding to the shoulders at 730 and 900 cm-1 lithium ion transference number.”
Electrical and structural studies of a LiBOB-based gel polymer electrolyte DOI: 10.1007/s11581-016-1834-7 -
Hydroxyl (O-H) confidence 1.0
“The Mn doping has in900 which correspond to strain vibration of O-H group of duced a change of particle shape, from the typical rod-like one 900 which correspond to strain vibration of O-H group of duced a change of particle shape, from the”
Harsono 等 - 2017 - Paramagnetic Zn(1-x)MnxO (0.00≤x≤0.06) Nanopar DOI: 10.4313/TEEM.2017.18.1.46 -
C c single bond confidence 1.0
“The strong cm-1 are weak, but those assigned to the C-C and C-O stretching is attributed to the C-C absorption peak at 1200~900 cm-1, vibrations of carbohydrate are strong at 1014~ 1020 and C-O stretching vibrations of carbohydrate.”
JOONSUK - 2019 - ATR-FTIR Analysis of Adhesives Jointing Buddhist S DOI: 10.12654/JCS.2019.35.1.02 -
Aromatic ring confidence 1.0
“The aromatic peak at 900 reconstruction to the z-score standardised aromatic peak(Figs.”
Shedding light on sporopollenin chemistry, with reference to UV reconstructions DOI: 10.1016/j.revpalbo.2016.11.014
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