What absorbs at 2905 cm⁻¹ in an FTIR spectrum?
A band near 2905 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 6 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkyl C-H | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
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Alkyl C-H confidence 1.0
“At 2905 cm-1, the band analogous to C-H asymmetric stretching occurs [36].”
Innovative Green Chemistry Approach to Synthesis of Sn2+-Metal Complex and Design of Polymer Composites with Small Optical Band Gaps DOI: 10.3390/molecules27061965 -
Carbonyl (C=O) confidence 1.0
“broadband at 3860 cm-1, characteristic intense bands corresponding to the asymmetrical and cm-1 Another group of signals associated with the cutin matrix is that from 1600 to 1750 attributed C=O symmetrical stretching vibrations of the meth”
Cutin from Solanum Myriacanthum Dunal and Solanum Aculeatissimum Jacq. as a Potential Raw Material for Biopolymers DOI: 10.3390/polym12091945 -
Alkyl C-H confidence 1.0
“Bands corresponding to asymmetric and symmetric C-H stretching vibrations of aliphatic -CH2 groups were observed at 2905 and 2860 cm-1 respectively (Figure 3).”
Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties DOI: 10.3390/polym10080826 -
Alkyl C-H confidence 1.0
“to 2970 and the CH band between 2905 and 2945 To further observe the relative lipid/protein content in”
Biophysical Stress Responses of the Yeast Lachancea thermotolerans During Dehydration Using Synchrotron-FTIR Microspectroscopy DOI: 10.3389/fmicb.2020.00899 -
Hydroxyl (O-H) confidence 1.0
“in the OH-stretching region, two broad bands are observed, centered at 2905 cm-1, and 2415 respectively (Figure 8).”
Neutron and XRD Single-Crystal Diffraction Study and Vibrational Properties of Whitlockite, the Natural Counterpart of Synthetic Tricalcium Phosphate DOI: 10.3390/cryst11030225 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Cheng 等 - 2018 - A new approach to improve mechanical properties an DOI: 10.1016/j.conbuildmat.2018.05.134
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