What absorbs at 1389 cm⁻¹ in an FTIR spectrum?
A band near 1389 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 1389 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 |
|---|---|---|---|
| Alkyl C-H | 4 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| Metal sulfur | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 0.9 |
| Amide | 1 | 0 | 0.9 |
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 |
|---|---|---|---|
| chitosan | 1389, 1650, 1655 | Alkyl C-H, Hydroxyl (O-H), C-O single bond | 1 |
| TiO2 | 1389, 1700, 1093 | Hydroxyl (O-H), Alkyl C-H, C-O single bond | 1 |
| TiO | 1389, 1730, 1699 | Alkyl C-H, Hydroxyl (O-H), C-O single bond | 1 |
| PLA | 1389, 1650, 1073 | Alkyl C-H, C-O single bond, Hydroxyl (O-H) | 1 |
| TiO2 nanoparticles | 1389, 1700, 455 | Hydroxyl (O-H), Alkyl C-H, C-O single bond | 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 1389 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
-
Carboxyl (COOH) confidence 1.0
“In the FTIR spectrum of pure alginate (AL) cm-1 powder , carboxyl peaks were observed near 1638 (symmetric COOstretching vibration) cm-1 and 1389 (asymmetric COO stretching vibration) [54].”
Niaz 等 - 2020 - Alginate-caseinate based pH-responsive nano-coacer DOI: 10.1016/j.ijbiomac.2019.11.177 -
confidence 1.0
“3379cm-1 3381cm-1 mightbeduetoCa-Ostretchingvibrations,whiletheintense and are ascribed to Al-OH and AlSi1123cm-1 bands at 953 and OH/Li-vibrations, respectively [36], since Al3+ and Fe3+ attributed to Si-O strong 1389cm-1 replace the Si4+”
Ahmad 等 - 2021 - Spectroscopic Analysis for Harnessing the Quality DOI: 10.1155/2021/6629640 -
Acetate confidence 1.0
“and CH 3/CO rocking vibrations with overlapping C-O-C stretching at 1113, 1145, and 1234 CH3 deformation vibrations occur at 1389 and 1463 cm-1.”
Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure DOI: 10.3390/app7060579 -
Alkyl C-H confidence 1.0
“The bands at 1456 and 1389 cm-1 attributed the methylene scissoring vibration in the proteins and C-O stretching vibration from carboxylate ion”
Kim 等 - 2019 - Highly Efficient and Stable Removal of Arsenic by DOI: 10.3390/ijms20143566 -
Metal sulfur confidence 1.0
“For MoS 2, the vibration cm-1 cm-1 mode at 1389 is assigned to Mo-S vibration, while the vibration mode at 1550 may be S-O asymmetric”
Hydrothermal synthesis of novel 1-aminoperylene diimide/TiO2/MoS2 composite with enhanced photocatalytic activity DOI: 10.1038/s41598-020-78894-y -
Aldehyde (CHO) confidence 1.0
“tions of aldehyde phenolic -OH groups, and bands cm-1, corresponding to the bending at 1389 and 1192 vibrations of phenolic -OH groups, are missing.”
Radoman 等 - 2015 - Effect of surface modified TiO2 nanoparticles on t DOI: 10.3144/expresspolymlett.2015.83 -
C-O single bond confidence 1.0
“The absorption peaks at 1490, 1455, sorption bands appeared at 3485, 2930, and 2890 cm-1 due to -OH stretching and aliphatic cm-1 and 1389 represent the C-OH bending vibration, methyl, and methylene group of”
Sathya Seeli 等 - 2023 - Zinc Oxide-Incorporated Chitosan-Poly(methacrylic DOI: 10.3390/jfb14040228 -
Borate confidence 1.0
“In the present glasses the strongest cm-1 infrared band around 1389 was assigned to B-O-B elongated vibrations of polymerized BO ions.”
Taqiullah 等 - 2018 - AC Conductivity and IR Spectroscopy of mixed alkal DOI: 10.1063/1.5042395
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