What absorbs at 1555 cm⁻¹ in an FTIR spectrum?
A band near 1555 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 1555 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 | 16 | 16 | 1.0 |
| Carboxyl (COOH) | 5 | 5 | 1.0 |
| Ring structure | 4 | 4 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Ketone | 3 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| C=n | 2 | 2 | 1.0 |
| Nitrogen heterocycle | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 0.9 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
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 1555 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
“In (NH3þ cm(cid:1)1 cm(cid:1)1 at 1638 the same way and according to Muyonga, Cole, and Duodu (2004), (amide I band of the acetyl group),1555 cm(cid:1)1 the amide I absorption band between 1600 and 1700 band, partially super-imposed with am”
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 -
Amide confidence 1.0
“Lipid is common in benign lymph node parenchyma and 1691cm(cid:2)1) (1500-1560cm(cid:2)1 and the Amide II with the principal may replace large areas of lymphoid tissue due to reactive features cm(cid:2)1) peak at 1555 bands which arise from”
Das 等 - 2008 - FTIR of touch imprint cytology A novel tissue dia DOI: 10.1016/j.jphotobiol.2008.05.012 -
Thiol confidence 1.0
“Thick horizontal bar shows S-H cm-1 the frequency region of the stretch known from the literature bands at 1555, 1504, 1404, 1352, 1270, and 1247 (38).”
Iwata 等 - 2003 - Light-induced structural changes in the LOV2 domai DOI: 10.1021/bi0345135 -
Amide confidence 1.0
“cm¡1.[27] MCM-41.[34] from vinyl chloride was detected at 677 The peak at cm¡1 OHC(cid:4)(cid:4)N(cid:4)(cid:4)H 1650 corresponded to (amide I), whereas the cm¡1 OHC(cid:4)(cid:4)N(cid:4)(cid:4)H II).[28,29] peak at 1555 was assigned to (am”
Modacrylic anion-exchange fibers for Cr\(VI\) removal from chromium-plating rinse water in batch and flow-through column experiments DOI: 10.1080/10934529.2017.1356192 -
Aromatic ring confidence 1.0
“The peak at cm-1 cm-1 1554.69 indicates the presence of aromatic ring vibration [32,39].”
Mahardiani 等 - 2022 - Nanofiber Fabrication from Palm Fiber Waste for Su DOI: 10.48317/IMIST.PRSM/morjchem-v10i2.32648 -
Amide confidence 1.0
“Similarly, the peaks at 1555 and 1550 represent the amide II band of non-infected 24 h and infected 24 h hemolymph, respectively (Fig.”
Antimicrobial potential of a ponericin-like peptide isolated from Bombyx mori L. hemolymph in response to Pseudomonas aeruginosa infection DOI: 10.1038/s41598-022-19450-8 -
Amide confidence 1.0
“LLM confirmed rule peak-group candidate”
Park 等 - 2000 - Vibrational Stark spectroscopy of NO bound to heme DOI: 10.1021/ja0014741 -
Amide confidence 1.0
“cm-1 cm-1 Elastin had two main peaks at around 1530 cm-1 and 1635 cm-1 that corresponded to the Elastin had two main peaks at around 1530 and 1635 that corresponded to amide II and amide I bonds, respectively [27], and these peaks overlappe”
A Study of Combining Elastin in the Chitosan Electrospinning to Increase the Mechanical Strength and Bioactivity DOI: 10.3390/md19030169
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