What absorbs at 2844 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2844 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

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 2844 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

• Alkyl C-H confidence 1.0

  “of2850-3000 stretch Variations in the range may be due FIGURE 4 (pbi-Br) XRD pattern of the 2Ir(acac) complex to double bonded =CH stretching, peaking at 2843.71 and 2 (pbi-Br) 2Ir(acac) complex exhibited no weight A thermogram of the cm-1”

  Synthesis and characterization of a green‐light‐emitting (pbi‐Br)2Ir (acac) metal complex for OLEDs DOI: 10.1002/bio.3565
• confidence 1.0

  “cm-1, diamond films prepared by CVD, are deposited under relative that for the ND sample, it has a new peak at 2844 which low pressure low temperature conditions where diamond is in we think is related to nitrogen impurity incorporation due”

  Tang 等 - 2007 - A comparison study of hydrogen incorporation among DOI: 10.1016/j.tsf.2006.10.132
• Lipid confidence 1.0

  “The peaks at 2952 cm-1, 2914 cm-1 and 2844 were characteristic peaks for polyethylene (PE)/paraffin wax (PW).”

  Fabrication and Performance of Phase Change Thermoregulated Fiber from Bicomponent Melt Spinning DOI: 10.3390/polym14091895
• Carbon dioxide confidence 1.0

  “Interestingly, the bands at 2916 and 2851 cm-1 in black tea shifted when the Co2+ polyphenol complexes formed, instead appearing at 2913 and 2844 cm-1, respectively.”

  Polymer Composites with 0.98 Transparencies and Small Optical Energy Band Gap Using a Promising Green Methodology: Structural and Optical Properties DOI: 10.3390/polym13101648
• Alkyl C-H confidence 1.0

  “observed, and for both PC1 and PC2 a minimum peak at ~2844 was detected, pointing to CH 3 and CH symmetric stretching vibrations, respectively (Figure 1D).”

  Effects of Cannabis Use on the Protein and Lipid Profile of Olfactory Neuroepithelium Cells from Schizophrenia Patients Studied by Synchrotron-Based FTIR Spectroscopy DOI: 10.3390/biom10020329