What absorbs at 740 cm⁻¹ in an FTIR spectrum?
A band near 740 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 740 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.
Iespējamie funkcionālo grupu piešķīrumi
| Funkcionālā grupa | Atbalstošie fakti | Citētie avoti | Augstākā pārliecība |
|---|---|---|---|
| Alkyl C-H | 7 | 7 | 1,0 |
| Aromatic ring | 5 | 5 | 1,0 |
| Ring structure | 3 | 3 | 1,0 |
| Phosphate (PO4) | 2 | 2 | 1,0 |
| Hydroxyl (O-H) | 2 | 2 | 1,0 |
| Fatty acid | 2 | 2 | 1,0 |
| Ester | 2 | 1 | 1,0 |
| Lipid | 1 | 1 | 1,0 |
| Borate | 1 | 1 | 1,0 |
| N-O bond | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Secondary amine | 1 | 1 | 1,0 |
| C n single bond | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Guanidine core | 1 | 1 | 1,0 |
| Metal oxo | 1 | 1 | 0,9 |
| Metal oxygen | 1 | 1 | 0,9 |
Rangs atspoguļo uzkrātos literatūras pierādījumus, nevis vienu autoritatīvu noteikumu. Vienmēr apstipriniet atbilstoši parauga kontekstam.
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 740 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.
Literatūra aiz šiem piešķīrumiem
-
Guanidine core pārliecība 1,0
“The guanidine peak is lower compared to 740 between modifi ed and untreated materials in relation to others.”
Uner 等 - 2016 - Wood Waste Turned Into Value Added Products Therm DOI: 10.5552/drind.2016.1534 -
Fatty acid pārliecība 1,0
“3 cm-1 2,800 and of the C = O absorption around 1,740 cm-1 was found to slightly increase, while the complex Fatty acid quantification by gas chromatography cm-1 absorption between 1,250 and 1,000 GC is the most used technique to evaluate l”
Ami 等 - 2014 - Fourier transform infrared spectroscopy as a metho DOI: 10.1186/1754-6834-7-12 -
Fatty acid pārliecība 1,0
“Infact, theester 1,740cm-1 in our experiments are most The response of the fatty acid ester bands in the same experiment band maxima at around (Figure 3B) likely representativeof asituationin which thesolventenvironment is coherent with thi”
Baserga 等 - 2022 - Membrane Protein Activity Induces Specific Molecul DOI: 10.3389/fmolb.2022.915328 -
Hydroxyl (O-H) pārliecība 1,0
“1442 and 1352 to the regions under 830 According to Liang, Marchessault Liang and Marchessault cm-1 [31, 32], these regions correspond to the O-H bending [31] suggested that the regions near 740 and 800 cm-1) in-plane vibration (1442 and th”
Rapid estimation of sugar release from winter wheat straw during bioethanol production using FTIR-photoacoustic spectroscopy DOI: 10.1186/s13068-015-0267-2 -
Ring structure pārliecība 1,0
“cm(cid:2)1 ThespectrumofO.Xappliiessentialoil(Figure3E)depictsfingerprint -CH 943 [14,15], 804 (TOH out of plane vibration) [14, 15] cm(cid:2)1 Carvat1254,1175,1116,995,937,864and813cm(cid:2)1[14,15] peaksof and 740 (TOH phenolic ring vibra”
Detection of carvacrol in essential oils by electrochemical polymerization DOI: 10.1016/j.heliyon.2020.e03714 -
Alkyl C-H pārliecība 1,0
“1E, 1F) record the appearcm-1 cm-1), and 1,660 aroC=O stretching (around 1,740 cm-1, cm-1, 780 and ance of some absorption peaks at 1,318 cm-1), and C-H matic ring skeleton vibration (around 1,545”
Ch'ng 等 - 2016 - Vasorelaxation Study and Tri-Step Infrared Spectro DOI: 10.3831/KPI.2016.19.016 -
Ring structure pārliecība 1,0
“At 670 °C, the degradation of the PI-2 occurs and in the FTIR spectrum, it can be observed only at the following absorption bands: 3430 cm-1 (-OH), 1584 cm-1 (C=C), 1445 cm-1 (P-Ar), 1384 cm-1 (C-H), 1117 cm-1 (P=O), 987 cm-1 (P-O-Ar) and 7”
Optical and Flame-Retardant Properties of a Series of Polyimides Containing Side Chained Bulky Phosphaphenanthrene Units DOI: 10.3390/ijms232113174 -
Aromatic ring pārliecība 1,0
“(1996) claimed that stronger 3 740cm-1) ] and SNS at around the peak of benzene ring interaction between ether groups and cations causes a larger s cm-1).”
Kim 等 - 2020 - Lithium Salt Dissociation in Diblock Copolymer Ele DOI: 10.3389/fenrg.2020.569442
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