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Raman Shift Calculator

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Convert between Raman shift (cm⁻¹) and scattered wavelength (nm) 🔬

Raman spectroscopy is a vibrational spectroscopy technique where the inelastic scattering of light (the Raman shift) is used to probe molecular vibrations, rotations, and low-frequency modes. These vibrational frequencies act as chemical fingerprints for identifying molecules and crystal structures. Raman shifts are typically expressed in wavenumbers (cm⁻¹), and this calculator converts between wavenumber, scattered wavelength, frequency (GHz), and phonon energy (meV).

🔢 Converter

1Select Excitation Laser Wavelength

Common lasers:

2Enter Either Value to Convert

—
Raman Shift (cm⁻¹)
—
Scattered λ (nm)
—
Raman Frequency (GHz)
—
Phonon Energy (meV)
📌 Unit equivalence (Δν = 1 cm⁻¹): f = 29.9792 GHz  |  E = 0.12398 meV
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📝 Raman Shift Formula

Raman shift expresses the frequency difference between the incident (excitation) and scattered light. The formula is:

Δν
=
(
1
λ₀
−
1
λ
)
× 10⁷
λ
=
1
1
λ₀
−
Δν
10⁷
  • Δν — Raman shift in wavenumber (cm⁻¹)
  • λ₀ — Excitation laser wavelength (nm)
  • λ — Scattered (Raman) wavelength (nm)
  • Inverse formula: λ = 1 / (1/λ₀ − Δν/10⁷)

Example (Diamond peak):

  1. Excitation laser: λ₀ = 532 nm
  2. Diamond's characteristic Raman peak: Δν = 1332 cm⁻¹
  3. Scattered wavelength: λ = 1 / (1/532 − 1332/10⁷) ≈ 572.2 nm

🔬 Raman Spectroscopy Knowledge

Raman Effect

🌊 Inelastic Light Scattering

Discovered by C.V. Raman in 1928. When photons interact with molecules, a small fraction undergo inelastic scattering, shifting in frequency. This shift is a molecular fingerprint.

cm⁻¹ vs nm

📏 Units Explained

Raman shifts are reported in wavenumber (cm⁻¹) because the shift is independent of the excitation wavelength, making spectra comparable across different laser sources.

Stokes / Anti-Stokes

⬆️⬇️ Two Types of Shifts

Stokes scattering (positive shift, λ > λ₀) is more common. Anti-Stokes scattering (negative shift, λ < λ₀) occurs from excited vibrational states and is temperature-dependent.

Common Peaks

💎 Reference Peaks

Diamond: 1332 cm⁻¹ | Silicon: 520 cm⁻¹ | Graphene G-band: ~1580 cm⁻¹ | Water (O-H stretch): ~3400 cm⁻¹. These are widely used for spectrometer calibration.