What absorbs at 1542 cm⁻¹ in an FTIR spectrum?
A band near 1542 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 1542 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 | 30 | 30 | 1.0 |
| N h | 7 | 7 | 1.0 |
| Secondary amine | 5 | 5 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Ketone | 4 | 4 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Carbonyl (C=O) | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Nitrogen heterocycle | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| Protein | 3 | 3 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Protein alpha helix | 2 | 2 | 1.0 |
| Protein beta sheet | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Protein beta turn | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Protein random coil | 1 | 1 | 0.8 |
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 |
|---|---|---|---|
| MWCNT | 1542, 2876, 1430 | Methacrylate, N h | 1 |
| PMMA | 1542, 1722, 1383 | Methacrylate | 1 |
| diamond | 1542, 1378, 1332 | Amide, Secondary amine | 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 1542 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 the amide II region, the peaks at 1542.07, cm-1 1541.96, 1541.83, and 1541.57 cm-1 were detectable for PG-FG 0-100, PG-FG 50-50, PG-FG observed.”
Application of Poultry Gelatin to Enhance the Physicochemical, Mechanical, and Rheological Properties of Fish Gelatin as Alternative Mammalian Gelatin Films for Food Packaging DOI: 10.3390/foods12030670 -
Nitrogen heterocycle confidence 1.0
“cm-1 613 The typical peaks at 1542 and 1468 attributed for the fundamental vibration of cm-1 pyrrole ring.”
Highly Biological Active Antibiofilm, Anticancer and Osteoblast Adhesion Efficacy from MWCNT/PPy/Pd nanocomposite DOI: 10.1016/j.apsusc.2017.10.142 -
confidence 1.0
“These calcium stearate at 1542 and 1575 bands are due to antisymmetric stretching bands for unidendate and bidendate association with calcium ions.”
Gonen 等 - 2010 - Preparation and Characterization of Calcium Steara DOI: 10.1021/ie901437d -
Protein confidence 1.0
“Cellular proteins produced peak assignments at the 1542 and 1644 wavenumbers which were attributed to the amide I and amide II bands of the polypeptide bond of proteins.”
Lane 和 Seo - 2012 - Attenuated Total Reflectance Fourier Transform Inf DOI: 10.1166/jnn.2012.6582 -
Protein confidence 1.0
“In our study, different band arcm-1 cm-1 (DNA), 1542 eas were found in the region related to proteins and DNA, specifically at 1085 cm-1”
Mostaco-Guidolin 等 - 2010 - Molecular and chemical characterization by Fourier DOI: 10.3233/SPE-2010-0466 -
Amide confidence 1.0
“They were α-helical 1542cm-1, 1649 and assigned to amide I of structhe FTIR spectrum characteristic of glutaraldehyde.”
Sukprasert 等 - 2020 - Synchrotron FTIR Light Reveals Signal Changes of B DOI: 10.1155/2020/6149713 -
Amide confidence 1.0
“Additionally, all the spectra showed the characteristic absorption cm-1 (C=O bands assigned to the peptide bonds in collagen (Figure 1B): 1630 for amide I stretching), cm-1 cm-1 1542 for amide II (N-H bending), and 1240 for amide III (C-N s”
Physicochemical and Biological Performance of Aloe Vera-Incorporated Native Collagen Films DOI: 10.3390/pharmaceutics12121173 -
Amide confidence 1.0
“The amide II band centered at 1542 results from three modes, a bending of a nitrogen and hydrogen bond (40-60%), a stretching of a carbonnitrogen bond (18-40%), and a stretching of a carbon-carbon bond (about 10%), N-H bend,”
Design and Development of a Bimodal Optical Instrument for Simultaneous Vibrational Spectroscopy Measurements DOI: 10.3390/ijms23126834
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.