What absorbs at 845 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 845 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 845 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

• Acetate 置信度 1.0

  “Raw MPF spectrum shows a broad peak at cm-1 cm-1 at 845 is due to the deformation vibration of C-O-C 3395 of O-H stretching.”

  Graft copolymerization of methyl methacrylate on Meizotropis Pellita fibres and their applications in oil absorbency DOI: 10.1007/s13726-020-00869-7
• N n bond 置信度 1.0

  “The bands at (n n cm-1 845 and 971 and are due to stretching vibrations of SiO and 3) and bands at 486 and N 4 1”

  Driving the photoluminescent and structural properties of X2-Y2SiO5 by varying the dopant Dy3+ concentration towards cool wLED applications DOI: 10.1016/j.solidstatesciences.2017.05.008
• Metal oxygen 置信度 1.0

  “The FTIR spectrum showed the absorption band at 845 cm-1 that is due to the stretching mode of is attributed to Bi-O-Bi bond, and the strong absorption band recorded at 424 Bi-O.”

  Zulkifli 等 - 2017 - Effect of Hydrothermal Reaction Time on Size of Bi DOI: 10.1063/1.5010448
• C-O single bond 置信度 1.0

  “PVAL was observed via its C-O stretching vibrations and contributed as vibrations and contributed as a shoulder of the band at 1170 cm-1 with its C-C-O cm-1 cm-1 a shoulder of the band at 1170 with its C-C-O stretching at 845 [26].”

  Polypyrrole Aerogels: Efficient Adsorbents of Cr(VI) Ions from Aqueous Solutions DOI: 10.3390/gels9070582
• Sulfate (SO4) 置信度 1.0

  “Vibration bands at 830 and 845 cm-1 have previously been associated with 4-Oand 2-O-sulfate groups in agar-type polysaccharides [46].”

  Exopolysaccharides Production by Cultivating a Bacterial Isolate from the Hypersaline Environment of Salar de Uyuni (Bolivia) in Pretreatment Liquids of Steam-Exploded Quinoa Stalks and Enzymatic Hydrolysates of Curupaú Sawdust DOI: 10.3390/fermentation7010033
• Aromatic ring 置信度 1.0

  “and aromatic ring vibrations at 971, 870 and 845 cm-1 (Figcm-1;”

  Advantages of External Reflection and Transflection over ATR in the Rapid Material Characterization of Negatives and Films via FTIR Spectroscopy DOI: 10.3390/polym14040808
• 置信度 1.0

  “The IR band at 845 shows the Leal et al.”

  Fernando 等 - 2017 - FTIR characterization and antioxidant activity of DOI: 10.4490/algae.2017.32.12.1
• C c single bond 置信度 1.0

  “cm-1 C-C C-O 1140 is due to the stretching of the and groups [53,54], the 1092 signal corresponds cm-1 C-O to the stretching of the group and the 845 stretch vibration corresponds to the C-C [54].”

  Judith Valdez-Alegria 等 - 2020 - Synthesis of Chitosan-Polyvinyl Alcohol Biopolymer DOI: 10.3390/biom10010156