What absorbs at 1505 cm⁻¹ in an FTIR spectrum?
A band near 1505 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 1505 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 |
|---|---|---|---|
| Aromatic ring | 12 | 11 | 1.0 |
| Lignin | 9 | 8 | 1.0 |
| Ring structure | 6 | 6 | 1.0 |
| Carbohydrate | 4 | 4 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 1 | 1.0 |
| C c single bond | 2 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Nitro (NO2) | 1 | 1 | 1.0 |
| N eq o | 1 | 1 | 1.0 |
| C-O single bond | 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 |
|---|---|---|---|
| lignin | 1505, 1035, 1510 | Lignin, Aromatic ring | 1 |
| wood | 1505, 1740, 1730 | Carbohydrate, Lignin, 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 1505 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
-
Aromatic ring confidence 1.0
“comparing the MCM-41 and MCM-41/PANI/ by tion of the surface area as well the pore volume for the cm(cid:1)1 Downloaded Ag spectra are the appearance of the band at 1505 lling composite corroborates the of the pores with PANI and vibration”
De Abreu Rosa 等 - 2013 - A one-pot synthesis of a ternary nanocomposite bas DOI: 10.1039/c3ra44618b -
Methoxy (OCH3) confidence 1.0
“Hardwood lignin changed more cm-1 cm-1 than softwood lignin, with a shift of maximum absorption from 1505 to approximately 1512 due to decrease of methoxyl groups, loss of syringyl units or breaking of aliphatic side-chains.”
Esteves 等 - 2013 - CHEMICAL CHANGES OF HEAT TREATED PINE AND EUCALYPT DOI: 10.4067/S0718-221X2013005000020 -
confidence 1.0
“1 cm-1 Another indication is a new peak at 1505 which is related to a typical amine ACCEPTED group, due to strongly hydrogen bonded to the hydroxyl groups with both of silanol and cellulose [26,32].”
Indarti 等 - 2019 - Silylation of TEMPO oxidized nanocellulose from oi DOI: 10.1016/j.ijbiomac.2019.05.161 -
Acetate confidence 1.0
“peak peak at 1738 for C O stretching gives evidence of carboxylic at 1738 The decrease in the intensity for the peaks at cm-1 cm-1 acid 1505 and ester group present in the hemicellulose, which entirely and 1456 after alkali treatment is a s”
Kasyapi 等 - 2013 - Bionanowhiskers from jute Preparation and charact DOI: 10.1016/j.carbpol.2012.10.021 -
Lignin confidence 1.0
“LLM confirmed rule peak-group candidate”
Examination of the lignin content in a softwood and a hardwood decayed by a brown-rot fungus with the acetyl bromide method and Fourier transform infrared spectroscopy DOI: 10.1002/pola.20071 -
Lignin confidence 1.0
“LLM confirmed rule peak-group candidate”
Pandey 和 Pitman - 2003 - FTIR studies of the changes in wood chemistry foll DOI: 10.1016/S0964-8305(03)00052-0 -
Carboxyl (COOH) confidence 1.0
“[11] observed bands at 1535 and 1505 cm-1, ascribed to the ν s(COO) vibration.”
Augugliaro 等 - 2008 - Photocatalytic oxidation of aromatic alcohols to a DOI: 10.1016/j.apcata.2008.07.038 -
N eq o confidence 1.0
“The peak observed at 1612 attributed to N-H bending vibrations of alkenes, primary amines, and amides, and the peak cm-1 can be attributed to N-H bending vibrations of alkenes, primary amines, and amcm-1 at 1505 can be assigned to N=O stret”
Eucalyptus globulus and Salvia officinalis Extracts Mediated Green Synthesis of Silver Nanoparticles and Their Application as an Antioxidant and Antimicrobial Agent DOI: 10.3390/plants11081085
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