Atomisation
Definition
Conversion of a sample into free gaseous atoms in the ground state (AAS) or excited state (AES). The mandatory first step of any atomic-spectroscopy technique.
- Definition
- Conversion of a sample into free gaseous atoms
- AAS state
- Ground-state atoms
- AES state
- Excited-state atoms
- Role
- Mandatory first step of atomic spectroscopy
- Common source types
- Flame, graphite furnace, or plasma
Common questions
Why must atomisation happen before an atomic spectroscopy measurement is possible?+
AAS and AES both measure light interacting with free atoms, either absorption or emission at wavelengths specific to an element. If the sample is still in molecular or ionic form, those atomic transitions cannot occur, so no useful signal is produced.
How does the atomisation step differ between AAS and AES?+
AAS relies on atoms remaining mostly in the ground state so they can absorb light from an external source at a characteristic wavelength. AES instead needs enough energy in the atomisation source to excite atoms so they emit light as they relax, so AES sources typically run hotter or use plasma.
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...
- Chromophore
- The molecular subunit responsible for a dye's colour, typically a conjugated double-bond system; chemical erasure destroys the chromophore while leaving the decolourised...
- Fingerprint Region (IR)
- 1500 to 400 cm⁻¹. The complex lower-wavenumber zone where the whole-molecule pattern is unique enough to identify a substance by overlay.
- Hollow Cathode Lamp (HCL)
- A sealed lamp whose cathode is made of the element being analysed, filled with argon or neon at low pressure. Strikes a...
- ICP Source
- Inductively coupled argon plasma at 6000 to 10000 K. The hottest practical excitation source for AES, giving simultaneous multi-element analysis (ICP-OES, ICP-MS).
- Molar Absorptivity (ε)
- The proportionality constant in the Beer-Lambert law, in L mol⁻¹ cm⁻¹. A property of the analyte at a given wavelength, solvent and...
- Stokes Shift (Raman)
- The Raman-scattered photon at lower energy than the incident photon. The Stokes line is the one routinely measured because it is stronger...