What absorbs at 1635 cm⁻¹ in an FTIR spectrum?
A band near 1635 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkene (C=C) | 12 | 11 | 1.0 |
| Amide | 10 | 10 | 0.95 |
| Water (H2O) | 7 | 6 | 0.95 |
| Hydroxyl (O-H) | 6 | 6 | 1.0 |
| Carbonyl (C=O) | 5 | 5 | 1.0 |
| Protein beta sheet | 4 | 4 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| C-O single bond | 1 | 1 | 0.95 |
| C=n | 1 | 1 | 0.9 |
| Carboxyl (COOH) | 1 | 1 | 0.9 |
| N h | 1 | 1 | 0.9 |
| Secondary amine | 1 | 1 | 0.8 |
| Aromatic ring | 1 | 1 | 0.8 |
| Alkyl C-H | 1 | 1 | 0.8 |
| Protein | 1 | 1 | 0.8 |
| Chitosan | 1 | 1 | 0.8 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
confidence 1.0
“Explicit assignment: '1590, 1607, 1635 (vibrational mode of furan)'”
Ballav 和 Biswas - 2004 - Preparation and evaluation of nanocomposites of po DOI: 10.1002/pi.1562 -
Alkene (C=C) confidence 1.0
“Explicit assignment in text.”
Rangayasami 等 - 2020 - Bioengineered silver nanoparticles using Elytraria DOI: 10.1016/j.bcab.2020.101690 -
Protein beta sheet confidence 1.0
“assigned to β-sheet”
Frare 等 - 2006 - Identification of the core structure of lysozyme a DOI: 10.1016/j.jmb.2006.06.055 -
confidence 1.0
“Sharp peak assigned to bending vibration of HH.”
Iannarelli 和 Rossi - 2014 - H2O and HCl trace gas kinetics on crystalline HCl DOI: 10.5194/acp-14-5183-2014 -
Carbonyl (C=O) confidence 1.0
“Band at 1635 cm-1 related to C=O and C-N stretching of amides.”
Perez-Puyana 等 - 2018 - Development of PVAgelatin nanofibrous scaffolds f DOI: 10.1088/2053-1591/aab164 -
Carbonyl (C=O) confidence 1.0
“C=O stretching.”
Perez-Puyana 等 - 2019 - Assessment of the denaturation of collagen protein DOI: 10.1515/hsz-2019-0206 -
Hydroxyl (O-H) confidence 1.0
“Bending vibration O-H indicated by absorption at 1635 cm-1.”
Suratman 等 - 2017 - Adsorption of CO2 by Alginate Immobilized Zeolite DOI: 10.1063/1.4978191 -
Water (H2O) confidence 0.95
“Explicit assignment in text: 'cm-1 at 1635 is due to the bending mode of vibration of water (H-O-H).'”
Parida 等 - 2004 - Studies on manganese-nodule leached residues - 1. DOI: 10.1016/j.jcis.2004.04.057
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