What absorbs at 742 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 742 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.

可能的官能团归属

排名反映了累积的文献证据，而非单一的权威规则。请始终对照您的样品背景进行确认。

Possible materials

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 742 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.

这些分配背后的文献

• 置信度 1.0

  “The band at cm-1 742 is probably due to the Ca-O bonds [7].”

  Characterization of quicklime as raw material to hydrated lime: Effect of temperature on its characteristics DOI: 10.1063/1.5066668
• C-S single bond 置信度 1.0

  “LLM confirmed rule peak-group candidate”

  Mesoporous Magnetic Cysteine Functionalized Chitosan Nanocomposite for Selective Uranyl Ions Sorption: Experimental, Structural Characterization, and Mechanistic Studies DOI: 10.3390/polym14132568
• Carbonyl (C=O) 置信度 1.0

  “The corresponding light minus dark FTIR difference spectrum ν(C=O) (Figure 4, in the region black line) shows a sigmoidal cm-1 and a positive peak at band with a negative peak at 1,742 cm-1, that are absent in the difference spectrum of the”

  Baserga 等 - 2022 - Membrane Protein Activity Induces Specific Molecul DOI: 10.3389/fmolb.2022.915328
• Acetate 置信度 1.0

  “The band at 742 cm-1 is assigned to the CH3 rocking cm-1 CH rocking mode, while 596 and 562 are related to [ νasGa-C 2] and [ νsGa-C 2].”

  Synthesis of High Surface Area—Group 13—Metal Oxides via Atomic Layer Deposition on Mesoporous Silica DOI: 10.3390/nano12091458
• Acetate 置信度 1.0

  “cm-1, cm-1, cm-1, cm-1, C-CH3 stretching at 1042-1046 cm-1, C-COO vibration assigned to 873 cm-1, (possibly due to the to 1095-1098 C-CH stretching at 1042-1046 C-COO vibration assigned to 873 3 cm-1, presence of CaCO3), C=O stretching assi”

  Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure DOI: 10.3390/app7060579
• C c single bond 置信度 1.0

  “The third one at 1477 cm-1 was associated with CH-cross deformations in CH 2-groups and the fourth band at 742 cm-1 was assigned to H-C-C-H-bound modes in the CH groups.”

  Fernández 等 - 2017 - DOI: 10.17230/ingciencia.13.25.6
• Phosphate (PO4) 置信度 1.0

  “The bending modes of the P-O bonds in phosphate groups are responsible for the double peak at 563 and 742 cm-1.”

  Synthesis and Characterization of New Composite Materials Based on Magnesium Phosphate Cement for Fluoride Retention DOI: 10.3390/ma16020718
• Acetate 置信度 1.0

  “cm-1 (imide carbonyl asymmetric stretching), 1715 (imide carbonyl symmetric stretchcm-1 ing and C=O stretching of carboxylic pendant groups), 1370 (C-N stretching), and cm-1 cm-1 742 (C=O bending).”

  Novel Polyimide/Copper-Nickel Ferrite Composites with Tunable Magnetic and Dielectric Properties DOI: 10.3390/polym