https://doi.org/10.1351/goldbook.08708
Measurement principle of spectroscopy to analyse molecular properties based on vibrations (bond stretching or deformation modes) in chemical species.
Note:
Typically, vibrational spectroscopy uses electromagnetic radiation lower in energy than the visible spectrum i.e., infrared or near infrared (see table).
Typically, vibrational spectroscopy uses electromagnetic radiation lower in energy than the visible spectrum i.e., infrared or near infrared (see table).
| Spectral region | Approximate wavelength (wavenumber) range | Energy transitions studied in matter | Analytical techniques (spectroscopy) |
|---|---|---|---|
| Gamma | 1-100 pm | Nuclear transitions and disintegrations | Gamma-ray |
| X-ray | 6 pm–100 nm | Ionization by inner electron removal | X-ray; X-ray fluorescence |
| Vacuum ultraviolet | 10–200 nm | Ionization by outer electron removal | |
| Ultraviolet | 200–400 nm | Excitation of valence electrons | UV-VIS |
| Visible | 400–780 nm | Excitation of valence electrons | UV-VIS |
| Near-infrared | 780 nm–2.5 μm (12 800–4000 cm-1) | Excitation of valence electrons; molecular vibrational overtones | Near-IR |
| Mid-Infrared | 2.5–25 μm (4000–400 cm-1) | Molecular vibrations: stretching and deformations | Infrared (IR) spectroscopy, Raman spectroscopy |
| Far-infrared | 25–1000 μm (400–10 cm-1) | Molecular rotations | Far-IR, Terahertz spectroscopy |
| Microwave | 0.1–30 cm | Molecular rotations and electron spin | Electron spin resonance, microwave spectroscopy |
| Radiofrequency | 10−1–103 m | Molecular rotations and nuclear spin | Nuclear magnetic resonance |