Band Spectrum
Definition
A continuous-looking envelope of closely spaced lines produced by molecules. Electronic, vibrational and rotational transitions couple together so a single electronic excitation appears as a band rather than a line. The basis of UV-Vis and IR molecular spectroscopy.
Related terms
- Beer-Lambert Law
- A = εbc. Absorbance equals molar absorptivity times path length times concentration. The linear relation between absorbance and concentration that makes UV-Vis...
- Line Spectrum
- A discrete pattern of sharp lines produced by atoms in the gas phase. Each element has a unique line pattern set by...
- Quantised Energy Level
- An allowed state of an atom or molecule. Transitions between levels happen only at discrete energies set by the level spacing, not...
- Selection Rule
- A quantum-mechanical rule that decides whether a transition between two levels is allowed or forbidden. Allowed transitions are intense and fast; forbidden...
- Wavenumber (Cm⁻¹)
- The number of wavelengths per centimetre, equal to 1/λ when λ is in cm. The working unit of vibrational spectroscopy because it...
Explained in
- Atomic and Molecular Spectra FundamentalsA continuous-looking envelope of closely spaced lines produced by molecules. Electronic, vibrational and rotational transitions couple together so a single ele...