Line Spectrum
Definition
A discrete pattern of sharp lines produced by atoms in the gas phase. Each element has a unique line pattern set by its electronic energy levels. The basis of AAS, AES, ICP-OES and XRF identification.
- Cause
- Discrete atomic energy transitions, gas phase
- Property
- Unique pattern per element
- Applications
- AAS, AES, ICP-OES, XRF identification
Common questions
Why does each element produce its own distinct line pattern?+
Electrons in an atom occupy specific energy levels unique to that element, so the exact wavelengths emitted or absorbed when electrons jump between levels form a fingerprint pattern for that element alone.
How is a line spectrum different from a continuous spectrum?+
A continuous spectrum shows unbroken light across a range of wavelengths, typically from a heated solid or liquid. A line spectrum shows only narrow, discrete wavelengths from gas-phase atomic transitions.
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...
- 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...