What absorbs at 1773 cm⁻¹ in an FTIR spectrum?
A band near 1773 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 1773 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 |
|---|---|---|---|
| Amide | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
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 |
|---|---|---|---|
| polyimide | 1773, 1720, 1778 | Amide, Carbonyl (C=O), Methacrylate | 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 1773 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
-
Amide confidence 1.0
“The peak at 1674 is assigned to peaks at 1773 and 1805 belong to the carbonyl group of EC.57 the amide peak belonging to DMF.”
Yusuf 等 - 2016 - From crab shell to solar cell a gel polymer elect DOI: 10.1039/C6RA04188D. -
Acetate confidence 1.0
“band at 1773 Since the strongest red shift of the C=O stretch among all dimer species N cm-1)”
FTIR matrix isolation and theoretical studies of glycolic acid dimers DOI: 10.1016/j.molstruc.2018.03.019 -
confidence 1.0
“cm-1 (N-H bending vibration in -CONH-) of PAA also vanished in PI spectrum, while new cm-1 were accounted for the C=O asymmetric stretching, C=O symmetrical stretching, and C-N stretching vibration in -CONHand -COOHgroups) and 1604 (N-H ben”
Preparation of Solution Blown Polyamic Acid Nanofibers and Their Imidization into Polyimide Nanofiber Mats DOI: 10.3390/nano7110395 -
confidence 0.9
“Text: 'bands at 1773 and 1713 cm-1 attributable to the pthalimido group'”
Synthesis and characterizations of phthaloyl chitosan-based polymer electrolytes DOI: 10.1016/j.jnoncrysol.2012.04.019 -
Carbonyl (C=O) confidence 0.9
“Assigned to cefepime.”
Ali 等 - 2017 - Solid-State FTIR Spectroscopic Study of Two Binary DOI: 10.1155/2017/5673214
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