What absorbs at 999 cm⁻¹ in an FTIR spectrum?
A band near 999 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 999 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 |
|---|---|---|---|
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Carbon dioxide | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 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 |
|---|---|---|---|
| cellulose | 999, 1735, 1650 | Acetate, Methacrylate, C-O single bond | 1 |
| TiO | 999, 1730, 1699 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| SiO | 999, 800, 1745 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| starch | 999, 1650, 1540 | Methacrylate, Acetate, C-O single bond | 1 |
| glycerol | 999, 1585, 1630 | Methacrylate, Acetate, C-O single bond | 1 |
| silver nanoparticles | 999, 1636, 1631 | Methacrylate, Acetate, C-O single bond | 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 999 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
-
Acetate confidence 1.0
“in-plane ring stretch C-O 1029.81 1029.81 1031.87 1029.81 1030 stretch C-O 998.96 998.96 985.58 998.96 1000 stretch 894-900 1-O-C 898.67 894.82 896.86 898.67 Asym.”
Dave 等 - 2014 - The removal of impurities from gray cotton fabric DOI: 10.1080/00405000.2013.827900 -
Carbohydrate confidence 1.0
“4000 3500 3000 2500 2000 1500 1000 stronger hydrogen bonding could be concluded from the double (cm-1) Wave Number 2919cm-1 2887cm-1 999cm-1 992cm-1 peaks at to and to in nanocomposites samples when compared with pure starch (Ding, Ainswort”
Glycerol/starch/Na+-montmorillonite nanocomposites: A XRD, FTIR, DSC and 1H NMR study DOI: 10.1016/j.carbpol.2010.10.018 -
Carbohydrate confidence 1.0
“Available online 2 March 2011 newlyformedhydrogenbonds,duetoplasticizerandnanoclayinteraction,andalsotheternaryinteraction among starch/sorbitol/nanoclay were taken from peaks associated with -OH stretching located at Keywords: 3300cm-1 and”
Preparation and characterization of sorbitol modified nanoclay with high amylose bionanocomposites DOI: 10.1016/j.carbpol.2011.01.058 -
Alkene (C=C) confidence 1.0
“C-O stretch stretch 1000 (s) 999 (s) =C-H C-O bend, stretch alkenes”
Siraj 等 - 2020 - Biosynthesized silver nanoparticles from shoot and DOI: 10.2306/scienceasia1513-1874.2020.097 -
C c single bond confidence 1.0
“In particular, ATRFTIR analysis of Cotton paper showed absorption at the band of cm-1, cm-1 999 as well as the C-C ring breathing band at ~1105 and the C-O-C glycosidic”
Banou 等 - 2023 - Oil Media on Paper Investigating the Interaction DOI: 10.3390/polym15112567 -
confidence 1.0
“C-O stretching.”
Cosma 等 - 2023 - Modification of Cotton and Leather Surfaces Using DOI: 10.3390/ma16041397 -
Acetate confidence 1.0
“cm-1 is indicated in the peak observed at 1583 Moreover, the peak observed at 1226 would indicate the cm-1 presence of carboxylic groups -COOH with its derivatives possibly such as carboxylates, the peak of 999 would correspond to the C-O b”
Adsorption of methylene blue from textile industrial wastewater using activated carbon developed from Rumex abyssinicus plant DOI: 10.1038/s41598-023-32341-w -
Alkyl C-H confidence 1.0
“In addition to, the C-H out-of-plane bending cm-1 cm-1 vibrations appear at 999, 967 and 770 for 2-ATP;”
Kalayci 等 - 2021 - EXPERIMENTAL AND THEORETICAL INVESTIGATIONS (FTIR, DOI: 10.4314/bcse.v35i3.11
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