What absorbs at 2100 cm⁻¹ in an FTIR spectrum?
A band near 2100 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 |
|---|---|---|---|
| Silicon hydride | 5 | 4 | 0.9 |
| C#c | 2 | 2 | 0.9 |
| Azide | 2 | 2 | 0.9 |
| Adsorbed carbon monoxide | 2 | 1 | 0.9 |
| Nitrile | 2 | 1 | 0.9 |
| Water (H2O) | 1 | 1 | 0.9 |
| C=n | 1 | 1 | 0.8 |
| C-O single bond | 1 | 1 | 0.8 |
| Alkene (C=C) | 1 | 1 | 0.8 |
| Thiocyanate | 1 | 1 | 0.7 |
| C n single bond | 1 | 0 | 0.9 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
confidence 1.0
“Absorption bands at 2100-2150 cm-1 corresponding to stretching mode of SiH_n.”
Rustamov 等 - 2018 - Reversible quenching of photoluminescence in stain DOI: 10.1016/j.jlumin.2017.11.011 -
Silicon hydride confidence 0.9
“Explicit assignment: 'Si-H stretching mode component at 2100 cm-1'.”
Chen 等 - 2014 - Effect of Deposition Power on the Structure Proper DOI: 10.4028/www.scientific.net/AMM.442.116 -
Silicon hydride confidence 0.9
“Text: 'Si-H stretching mode shifts from 2000 to 2100'”
Hou 等 - 2011 - Evolution of infrared spectra and optical emission DOI: 10.1088/1674-1056/20/7/077802 -
Adsorbed carbon monoxide confidence 0.9
“Sharp peak at ~2100 cm-1 assigned to CO vibration on Au.”
Powell 等 - 2017 - CO Adsorption on AuTiO2 Catalysts Observations, DOI: 10.1021/acs.jpcc.7b07249 -
confidence 0.9
“Text states 'IR peak observed near 2100 cm-1' and 'Au0 2100 cm-1'.”
Shekhar 等 - 2012 - Counting Au catalytic sites for the water-gas shif DOI: 10.1016/j.jcat.2012.06.008 -
confidence 0.9
“Text: 'band at 2100 indicating stretching vibrations between C=C=O groups (ketenes)'.”
Coria-Hernandez 等 - 2018 - Thermal, Structural, and Rheological Characterizat DOI: 10.3390/polym10040359 -
Water (H2O) confidence 0.9
“Explicit assignment: 'FTIR peak centred at 2100 can be assigned to free water in starch'”
Dankar 等 - 2018 - Characterization of food additive-potato starch co DOI: 10.1016/J.CARBPOL.2011.05.064 -
Azide confidence 0.9
“Text: 'absorbance band at 2100 characteristic of the presence of azide'”
Joubert 等 - 2015 - Graft copolymers of hydroxyethyl cellulose by a 'g DOI: 10.1039/x0xx00000x
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