What absorbs at 1630 cm⁻¹ in an FTIR spectrum?
A band near 1630 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 1630 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
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 |
|---|---|---|---|
| Zinc Oxide Nanoparticles | 1630, 1744, 1627 | Hydroxyl (O-H), Amide | 1 |
| humic acids | 1630, 1510, 1108 | Hydroxyl (O-H), Amide | 1 |
| dentin | 1630, 575, 1740 | Amide, Carbonyl (C=O) | 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 1630 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
-
Hydroxyl (O-H) confidence 1.0
“The bending at 1630 cm-1 is attributed to the H-O-H bonding due to the water molecules ad-”
Synthesis and Characterization of Zinc Oxide Nanoparticles Using Acacia caesia Bark Extract and Its Photocatalytic and Antimicrobial Activities DOI: 10.3390/catal11121507 -
Carbonate confidence 1.0
“of the H 2O bending band at 1630 Carbonate bands with absorbance cm-1 combination bands at 4500 and 5200 and the tetrahedral <0.2 are not sufficiently well-separated from background features in the (Al3+ Si4+)/sum [τ cation fraction = + of”
Behrens 等 - 2009 - Solubility of H2O and CO2 in ultrapotassic melts a DOI: 10.2138/am.2009.2796 -
Acetate confidence 1.0
“(cm-1) Component Spectral band Associated vibration C-C/C-O COM 780 single bond stretching C-C/C-O 1318 single bond stretching C-O 1630 double bond stretching C-O COD 1680 double bond stretching”
High precision mapping of kidney stones using mu;IR spectroscopy to determine urinary lithogenesis DOI: 10.1002/jbio.201300201 -
Carboxyl (COOH) confidence 1.0
“LLM confirmed rule peak-group candidate”
Ch'ng 等 - 2011 - Qualitative Assessment of Soil Carbon in a Rehabil DOI: 10.1100/tsw.2011.54 -
Water (H2O) confidence 1.0
“LLM confirmed rule peak-group candidate”
Characterization of Modified Tapioca Starch in Atmospheric Argon Plasma under Diverse Humidity by FTIR Spectroscopy DOI: 10.1088/0256-307X/30/1/018103 -
Amide confidence 1.0
“The 1630 peak corresponds to the stretching vibration of C¼¼O bond cm-1 (mC¼¼O) from amide I, and the 1580 peak corresponds”
Root canal hydrophobization by dentinal silanization: Improvement of siliconbased endodontic treatment tightness DOI: 10.1002/jbm.b.32874 -
Alkene (C=C) confidence 1.0
“At 1630 C=C stretching cm-1.”
Fatima 等 - 2021 - Extraction and Chemical Characterization of Humic DOI: 10.3390/su13168969 -
Alkyl C-H confidence 1.0
“ACAH C‚O stretch, stretch, stretch, conjugated achieved the maximum for 40 min, the transmissivity of the C‚C CAO stretch or stretch, CH bend, stretch and acetyle2 cm-1, cm-1 cm-1 peaks at 1630 1390 and 600 achieved the max-”
Ge 等 - 2017 - Characteristics of activated carbon remove sulfur DOI: 10.1016/j.sjbs.2016.12.016
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.