What absorbs at 2159 cm⁻¹ in an FTIR spectrum?
A band near 2159 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 2159 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 |
|---|---|---|---|
| Silicon hydride | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Sulfur | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Bronsted acid site | 1 | 1 | 1.0 |
| Bromine | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| C#c | 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 |
|---|---|---|---|
| GO | 2159, 1720, 1182 | Hydroxyl (O-H) | 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 2159 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
-
Silicon hydride confidence 1.0
“Figure 14 shows the changes in the silane peak at 2159 The silane peak did not show any intensity for neat asphalt and LPs of CRMA binders interacted at 160-10 or 160-50.”
Effect of used motor oil as a rejuvenator on crumb rubber modifier’s released components to asphalt binder DOI: 10.1177/1477760620918600 -
Silicon (Si) confidence 1.0
“cm-1 ν to step-by-step building up procedure outlined above where DOD, and the 2140 involved solely the three DH, as cm-1 Si-H the particularly grouped species provided the best (Figures S12 and plus two shoulder peaks 2148 and 2159 cm-1 ag”
FTIR Measurement of the Hydrogenated Si(100) Surface: The Structure-Vibrational Interpretation by Means of Periodic DFT Calculation DOI: 10.1021/acs.jpcc.0c11176 -
Silicon hydride confidence 1.0
“The cm-1 cm-1 bands at 2159 (S-1) and 2165 (S-28) can be assigned to SiH stretching mode in the small grains, gradually exposed to oxidation during combustion process at intermediate temperature during synthesis given phases.”
Colovic 等 - 2013 - Creating of Highly Active Calcium-Silicate Phases DOI: 10.2298/SOS1303341C -
Alkyl C-H confidence 1.0
“Even cm-1 though the band at 2159 represents the ethene CH antisymmetric stretch compound cm-1 and CH 2=CH as a functional group, the bands at 2926 indicate the presence of the”
Maher 等 - 2021 - Optimization of Ultrasound-Assisted Extraction of DOI: 10.3390/antiox10101612 -
Hydroxyl (O-H) confidence 1.0
“There is also a small band of Pt in the oxidized sites in cm-1, cm-1 2159 while in 3374 the band corresponds to HOH doubling and OH narrowness.”
Mayorga 等 - 2020 - Bio-hydrogen production using metallic catalysts DOI: 10.24275/rmiq/Cat652 -
Bromine confidence 1.0
“3𝐶𝑢𝐼𝐼NO cm-1 cmand 1575 appear, which have been assigned to species (1625, 1610 and 1575 1).[4b, 13b, 14-15] cm-1 NO+ The weak band at 2159 indicates the formation of the nitrosonium ion cm-1 below).[15-16] exchanging Brønsted sites (see Th”
Negri 等 - 2018 - Investigating the Low Temperature Formation of Cu- DOI: 10.1002/chem.201802769 -
Hydroxyl (O-H) confidence 1.0
“Considering the asymmetry on cm-1, the low frequency side of the band centered at 2159 modes due to CO physisorption on heterogeneous surface sites, including residual OH groups and/or sulfur anions on the cm-1 basal planes of crystalline M”
Few-Layered MoS2 Nanoparticles Covering Anatase TiO2 Nanosheets: Comparison between Ex Situ and In Situ Synthesis Approaches DOI: 10.3390/app1101 -
C#c confidence 0.9
“Explicit: 'band at 2159 for (Figure S1)' and context of acetylenic spacer.”
Mateos-Gil 等 - 2015 - Electroactive carbon nanoforms a comparative stud DOI: 10.1039/c0xx00000x
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