What absorbs at 1201 cm⁻¹ in an FTIR spectrum?
A band near 1201 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 5 cited sources
Quick answer
A band near 1201 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 |
|---|---|---|---|
| Methacrylate | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 0.9 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| polyamide | 1201, 1663, 1541 | Amide, Methacrylate, Acetate | 1 |
| polypyrrole | 1201, 1700, 400 | Amide, Methacrylate, Acetate | 1 |
| TiO | 1201, 1730, 1699 | 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 1201 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
-
Ring structure confidence 1.0
“cm-1 (asymmetric C=O stretching vibration of carboxylate), 1555 (Py ring stretching cm-1 cm-1 vibration), 1476 (Py ring stretching and C-H in-plane stretching vibration), 1319 cm-1 cm-1 (C-N in-plane deformation), 1201 (Py ring vibration),”
New conductive copolymer membranes via track-etched PC templates for biological media ultra-filtration DOI: 10.1016/j.nimb.2007.08.066 -
Acetate confidence 1.0
“The absorption-free regions of the NWF-PP ATR-FTIR spectrum of samples treated with cloves buds extract allow the clear identification of the characteristic signals of polywithclovesbudsextractallowtheclearidentificationofthecharacteristics”
Cicogna 等 - 2022 - Surface Functionalization of Face Masks with Cold DOI: 10.3390/molecules27238632 -
C c single bond confidence 1.0
“The difference spectra have negative bands at 1201 and 1169 arise from C-C stretching been scaled to match the intensity of the amide II bands vibrations of the retinal in ground state bR.”
Time-Resolved Microspectroscopy on a Single Crystal of Bacteriorhodopsin Reveals Lattice-Induced Differences in the Photocycle Kinetics DOI: 10.1529/biophysj.106.083345 -
Hydroxyl (O-H) confidence 1.0
“2 1200, 1208 1201 cm-1) O-H deformation (1208 hemicelluloses [45] C=O stretching vibrations in lignin, acetyl and carboxyl vibrations in xylans [44] 1222, 1230, 1233, 1234 1230-1236”
Study of Interactions between Titanium Dioxide Coating and Wood Cell Wall Ultrastructure DOI: 10.3390/nano12152678 -
Alkyl C-H confidence 0.9
“Explicit assignment: fanning vibration of CH group.”
Influence of Cross-Linking Agent Concentration/Beta Radiation Surface Modification on the Micro-Mechanical Properties of Polyamide 6 DOI: 10.3390/ma14216407
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