Quantised Energy Level
Definition
An allowed state of an atom or molecule. Transitions between levels happen only at discrete energies set by the level spacing, not at any arbitrary energy. The discreteness is what makes spectra characteristic rather than continuous.
Related terms
- Band Spectrum
- A continuous-looking envelope of closely spaced lines produced by molecules. Electronic, vibrational and rotational transitions couple together so a single electronic excitation...
- 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...
- 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 FundamentalsAn allowed state of an atom or molecule. Transitions between levels happen only at discrete energies set by the level spacing, not at any arbitrary energy. The...