What absorbs at 620 cm⁻¹ in an FTIR spectrum?
A band near 620 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 620 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 |
|---|---|---|---|
| Metal oxygen | 12 | 10 | 1.0 |
| Alkyl C-H | 6 | 6 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Silicon hydride | 3 | 2 | 1.0 |
| Silicon (Si) | 3 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Protein random coil | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 0.7 |
| Silicon silicon | 1 | 0 | 1.0 |
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 |
|---|---|---|---|
| diamond | 620, 1378, 1332 | Alkyl C-H, 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 620 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
-
confidence 1.0
“The cm-1, which are FTIR spectra show the presence of two absorption bands at around 620 and 390 Jo due to stretching and bending vibrations of the Ti-O bond, respectively.”
Hemeda 等 - 2021 - Synthesis of nanometer-sized PbZrxTi1-xO3 for gamm DOI: 10.1016/j.jpcs.2020.109688 -
Hydrogen bond confidence 1.0
“pertains to a bonding structure of a typical a-Si:H, and cm-1 ∼620 the peak is regarded as an indication of For films with S ranging from 3% to 10%, c changes in the hydrogen bonding environment or of the Si-H stretching mode can be de-conv”
Hou 等 - 2011 - Evolution of infrared spectra and optical emission DOI: 10.1088/1674-1056/20/7/077802 -
confidence 1.0
“The peak at 620 is associated with substitutional boron lattice positions.”
Jagannadham 等 - 2007 - Neutron transmutation of B-10 doped diamond DOI: 10.1016/j.diamond.2006.03.019 -
Alkyl C-H confidence 1.0
“The origin cm-1 of the vibration bands is as follows: at 3389 due to the NH stretching vibrations, cm-1 cm-1 at 2936 due to a CH-stretching vibrations, at 620 due to CH out-of-plane bending vibration.”
Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application DOI: 10.1063/1.4948838 -
Metal oxygen confidence 1.0
“LLM confirmed rule peak-group candidate”
Photocatalytic and antibacterial activities of hydrothermally prepared CdO nanoparticles DOI: 10.1007/s10854-017-6937-z -
Metal oxygen confidence 1.0
“However, there is a 620cm-1, newly forming Sn-O stretching vibration peak at which demonstrates that the precursors”
Liu 等 - 2012 - Preparation and Properties of Gd and Sb Doped SnO2 DOI: 10.4028/www.scientific.net/AMR.528.50 -
Protein confidence 1.0
“Concerning the matrix and also from the FTIR spectra, and in the calcareous dolomites of the Monastery of Silos, Spain, the absence of specific bands of the following species: proteins whose origin is either the application of calcium casei”
Martin-Gil 等 - 2005 - The orange-brown patina of Salisbury Cathedral (We DOI: 10.1065/espr2005.05.257 -
confidence 1.0
“MnFe 2O Nanoparticles as an Efficient Electrode for Energy Storage Applications 4 29.6(cid:3), 34.9(cid:3), 42.4(cid:3), 52.6(cid:3), cm-1 (A 1g(cid:2) The diffraction angle located at the broad peak at 620 corresponds to the 56.1(cid:3), 6”
Saravanakumar 等 - 2020 - MnFe2O4 Nanoparticles as an Efficient Electrode fo DOI: 10.1166/jnn.2020.17187
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