What absorbs at 875 cm⁻¹ in an FTIR spectrum?
A band near 875 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 875 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 |
|---|---|---|---|
| Carbonate | 18 | 17 | 1.0 |
| Alkyl C-H | 12 | 12 | 1.0 |
| C-O single bond | 12 | 11 | 1.0 |
| Methacrylate | 10 | 9 | 1.0 |
| Acetate | 10 | 9 | 1.0 |
| Methoxy (OCH3) | 9 | 8 | 1.0 |
| Phosphate (PO4) | 8 | 8 | 1.0 |
| Aromatic ring | 6 | 6 | 1.0 |
| Ring structure | 6 | 6 | 1.0 |
| Metal oxygen | 5 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Carbohydrate | 4 | 4 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Phosphorus | 2 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Oxygen heterocycle | 2 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 1 | 1.0 |
| Silicon (Si) | 2 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Sulfonate | 1 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| Silicate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Silicon nitrogen | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 875 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
-
Silicon (Si) confidence 1.0
“The 813 band and the 875 shoulders can be unambiguously assigned to the transverse (TO) and the longitudinal (LO) modes of the asymmetric Si-N stretching vibration, respectively.”
Benyahia 等 - 2017 - Evolution of Optical and Structural Properties of DOI: 10.4028/www.scientific.net/JNanoR.49.163 -
Ring structure confidence 1.0
“cm-1 The existence of the epoxide ring in the purified ENR-25 is shown by peak at 875 due to half ring”
Dahham 等 - 2018 - The Influences of Zirconium Dioxide on ENR-25ZrO2 DOI: 10.1088/1742-6596/1019/1/012055 -
Metal oxygen confidence 1.0
“cm-1 the range 600-4000 The characteristic peak observed at 875 which is attributed cm-1 is corresponding to the due to the stretching frequency of Y-O.”
Jayaramaiah 等 - 2015 - Luminescence performance of europium-doped yttrium DOI: 10.1016/j.jlumin.2014.08.003 -
confidence 1.0
“The clean calcium solid The cement treatment changed the leaching behavior of cm-1, showed two peaks at 875 and 712 corresponding to arsenic in the material.”
Jing 等 - 2003 - Immobilization mechanisms of arsenate in iron hydr DOI: 10.1021/es021027gCCC -
Lignin confidence 1.0
“The band at 875 can be assigned to lignin monomers and”
Effects of the biomass moisture content and pelleting temperature on the pressure-induced agglomeration process DOI: 10.1016/j.biombioe.2017.10.029 -
Phosphate (PO4) confidence 1.0
“(cm-1) Wavenumbers Bonds / Vibrations 1057.6 PO4 bond, P=O stretching vibrations 986.2 P-O-P asymmetric stretching bond 875.2 P-O-P asymmetric stretching bond”
Growth and characterization of calcium hydrogen phosphate dihydrate crystals from single diffusion gel technique DOI: 10.1002/crat.200900700 -
Aromatic ring confidence 1.0
“700-900cm-1 860cm-1) The prominent absorption signals at (peaking at 875 and are due to aromatic CHoutofplanedeformation.Anarrow,strongbandiscentredat1540cm-1 whichcouldbeCOOHband.”
Sharma 等 - 2009 - On the affinity of Chuaria-Tawuia complex A multi DOI: 10.1016/j.precamres.2009.04.003 -
Phosphate (PO4) confidence 1.0
“Besides, HPO band at 875 tend 4-2 to decrease as the Mg concentration increased.”
Toibah 等 - 2012 - FTIR Study on Phase Behavior of Magnesium-doped Bi DOI: 10.1063/1.4732476
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