What absorbs at 673 cm⁻¹ in an FTIR spectrum?
A band near 673 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 673 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 |
|---|---|---|---|
| Borate | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Bronsted acid site | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 0 | 1.0 |
| Silicon (Si) | 1 | 0 | 1.0 |
| Alkyl C-H | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 673 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
-
Bronsted acid site confidence 1.0
“The increase in wavenum1500, 1576, and 1604 While both monodentate nitrates cm-1, ber of this peak at temperatures above 423 K can be interpreted s(NH 3) may be overlapping to form the peak at 1245 and (cid:228) as the desorption of NH from”
Pena 等 - 2004 - Identification of surface species on titania-suppo DOI: 10.1021/jp0313122 -
Carbonyl (C=O) confidence 1.0
“Since these bands were stable toward evacuation at 673 cm-1) (together with a component around 2155 decreased in frequency)58 K (which is not typical of carbonyl bands at this 13CO concert (note that at very high coverages the satellite of”
Penkova 等 - 2007 - Effect of the preparation method on the state of n DOI: 10.1021/jp071927p -
C-S single bond confidence 1.0
“It is also noticed from the cm-1 1100 figure that the intensity of the CdTe peak decreases and the existence of C-S stretching vibracm-1, with the annealing temperature (shown in Figure S6) tions is indicated by the bands at 673 respecwhich”
A novel CdTe ink-assisted direct synthesis of CdTe thin films for the solution-processed CdTe solar cells DOI: 10.1007/s10853-020-04578-7 -
Ring structure confidence 1.0
“The appearance of a new peak at 673 in case of photo-degraded samples indicates the aromatization of PFA ring.”
Singh 等 - 2022 - Degradation of Polyfurfuryl Alcohol-Based Biopolym DOI: 10.21203/rs.3.rs-546187/v1 -
confidence 1.0
“565.7 in The strong intensity absorption peaks at 672.6 are due to the stretching vibration of the Ni-Cl bond in complex 2.”
Structures, Characterization and DFT Studies of Four Novel Nickel Phenanthroline Complexes DOI: 10.3390/cryst13050738 -
confidence 1.0
“However, with the cm-1 exception of a small band at 673 (S-O bend), no other characteristic absorption for sulfates can be seen;”
Assessment of Easily Accessible Spectroscopic Techniques Coupled with Multivariate Analysis for the Qualitative Characterization and Differentiation of Earth Pigments of Various Provenance DOI: 10.3390/min12060755 -
confidence 1.0
“hyd [3b, 3e] cm-1 The NRVS features in the 400-600 range, having weaker intensities and higher vibrational energies than the Fe-S bands, are mostly from modes with Fe-CN/CO character, previously.[13] as reported cm-1, At still higher energi”
Terminal Hydride Species in [FeFe]-Hydrogenases are Vibrationally Coupled to the Active Site Environment DOI: 10.1002/anie.201805144. -
Borate confidence 1.0
“IR band positions observed 673 in BCAPM glasses indicates cm1 the elongations of B-O-B bonds in BO units groups[36].”
Rajesham 等 - 2022 - Synthesis, physical, optical and structural studie DOI: 10.21203/rs.3.rs-1495935/v1
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