What absorbs at 609 cm⁻¹ in an FTIR spectrum?
A band near 609 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 7 cited sources
Quick answer
A band near 609 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 |
|---|---|---|---|
| N h | 2 | 2 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Carbon bromine | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 0.9 |
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 609 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
-
Carbon bromine confidence 1.0
“In the last bottom peak, at 609 cm-1, an alkyl halides absorbance of the shell-based conventional lubricant and the other two peaks represent (C-Br) functional group was attached.”
Tribological Analysis of Molybdenum Disulfide (MOS2) Additivated in the Castor and Mineral Oil Used in Diesel Engine DOI: 10.3390/su141710485 -
Metal oxygen confidence 1.0
“Two absorption bands are cm-1, associated with the coupling between Mn-O stretching observed at 609 and 495 modes of tetrahedral and octahedral sites [19, 20].”
Baykal 等 - 2007 - Low temperature synthesis and characterization of DOI: 10.2478/s11532-006-0064-7 -
C-S single bond confidence 1.0
“FTIR analysis of the dried seaweed and colloid extracts from Bonds/Assignments (cm-1) Wavelength Numbers 609 C-S stretching vibrations (agar) 690 3,6anhydro-L-galactose (agar)”
Extraction and Analysis of Compounds with Antibacterial Potential from the Red Alga Grateloupia turuturu DOI: 10.3390/jmse7070220 -
confidence 1.0
“The XRD spectrum of Agr shows a peak 19.1◦ ∼ 2θ 1556.6 cm-1 and 1404.6 cm-1, N-H out of plane wagging at 608.8 cm-1, and C-H stretching at 928.2 at with the intensity of 1624 (a.u), which demonstrates the semi-crystalline nature of ∼ at 2θ”
Development of Biodegradable Agar-Agar/Gelatin-Based Superabsorbent Hydrogel as an Efficient Moisture-Retaining Agent DOI: 10.3390/biom10060939 -
confidence 1.0
“Discussion 300 stretching, amide II), 1,609 cm-1 (-N-H), and 1,658 cm-1 (C=O stretching, amide I) [10].”
Omir 等 - 2020 - Behaviour of Aquaporin Forward Osmosis Flat Sheet DOI: 10.3390/membranes10050108 -
Phosphate (PO4) confidence 0.9
“Explicit assignment: 'PO group at ... 609'”
Natasha 等 - 2008 - Fourier transform infrared study on sol-gel derive DOI: 10.4028/www.scientific.net/AMR.47-50.1185 -
confidence 0.8
“Text: '608.7cm-1 ν respectively' (bending mode)”
Wang 等 - 2005 - Nanostructure properties of hydroxyapatite nanobel DOI: 10.4028/www.scientific.net/KEM.288-289.187
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.