FTIR Spectrum Chart

This chart provides a visual overview of where major functional groups absorb in the infrared spectrum. Use it as a quick reference when interpreting FTIR spectra, or print it for lab use. Each colored bar spans the typical absorption range for that bond type. For detailed numeric data, see the full FTIR absorption table.

Wavenumber decreases left to right (4000 → 400 cm⁻¹). Background shading shows the four spectral regions.

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Reading the Chart

The horizontal axis represents wavenumber in cm⁻¹, running from 4000 on the left to 400 on the right — the standard orientation for infrared spectra. Each horizontal bar marks the range where a particular bond vibration absorbs. Bars are grouped by functional group category and color-coded: green for alcohols, red for carbonyls, purple for amines, blue for aromatics, gray for alkanes, and orange for nitro compounds. If a bar overlaps with another, multiple functional groups may absorb at that wavenumber — use peak shape and intensity to distinguish them.

The Four Spectral Regions

The mid-infrared range (4000–400 cm⁻¹) is divided into four diagnostic regions, each dominated by specific bond types. The background shading on the chart above corresponds to these regions.

Region	Wavenumber Range	Key Bonds
X-H Stretching	4000–2500 cm⁻¹	O-H, N-H, C-H stretches
Triple Bond	2500–2000 cm⁻¹	C≡C, C≡N
Double Bond	2000–1500 cm⁻¹	C=O, C=C, C=N
Fingerprint	1500–400 cm⁻¹	C-O, C-N, C-C stretches; bending modes

Print or Save This Chart

Press Ctrl + P (Windows) or Cmd + P (Mac) to open the print dialog. The site's print stylesheet automatically hides navigation and non-essential elements, leaving just the chart and text content. Choose “Save as PDF” in the print dialog to keep a digital copy for offline reference.

For Detailed Data

This chart shows the most common functional group absorptions at a glance, but the full dataset includes 125 entries with peak shape, intensity, and bond-type metadata. Explore the complete interactive FTIR spectrum table to search by wavenumber, filter by category, and sort by any column. For guidance on interpreting spectra step by step, read the how to read FTIR spectra guide. You can also explore specific topics like the fingerprint region and carbonyl peak assignments.

Frequently Asked Questions

What does an FTIR spectrum chart show?

An FTIR spectrum chart displays the wavenumber ranges where different functional groups absorb infrared radiation. Each horizontal bar represents a specific bond vibration (such as O-H stretch or C=O stretch), positioned at its characteristic wavenumber range between 4000 and 400 cm⁻¹. The chart provides a quick visual reference for identifying which molecular bonds are responsible for observed absorption peaks.

How do I use an infrared absorption bands chart?

Locate the wavenumber of a peak in your experimental spectrum on the horizontal axis, then check which colored bars span that position. Each bar corresponds to a functional group that absorbs in that range. Use peak shape and intensity to distinguish between overlapping groups, and confirm with corroborating peaks from the same functional group.

Can I print this FTIR chart for lab use?

Yes. Press Ctrl+P (Windows) or Cmd+P (Mac) to open the print dialog. The page's print stylesheet automatically hides the navigation and other non-essential elements, leaving just the chart and text content. Select “Save as PDF” for a digital copy you can reference offline.