1. The ratio of excited state to ground state atoms as a function of temperature is determined by the Maxwell-Boltzmann expression.
Fig Excited state to ground state population ratio for photon energies of nm at temperatures from K.

2. Nearly all the gaseous atoms are in the ground state.
Atomic emission is still sensitive because the baseline signal is zero.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

3. (a) Nebulizer, chamber, and burner. (b) Burner head.
The fuel and support gases mix in the chamber.
The sample is aspirated through a capillary by the Venturi effect, using the support gas.
A fine spray if produced, with larger droplets condensing and draining out the chamber.
Fig Premix burner.
(a) Nebulizer, chamber, and burner. (b) Burner head.

4. Fig. 17.3 Processes occurring in flame.
The dehydrated salt dissociates into gaseous atoms in the ground state.
A small fraction is thermally raised to an excited electronic state.
These emit photons of characteristic wavelength (line spectra) when dropping to the ground state.
In flame emission, we measure K0*.
In atomic absorption, we measure K0.
Fig Processes occurring in flame.

5. Fig. 17.4. Schematic diagram of atomic absorption instrument.
This is a double-beam instrument that measures the ratio of P0/P.
The hollow-cathode lamp emits the resonance lines of the test element.
These are only absorbed by the test element atomic vapor (except for broad band absorbers).
Fig Schematic diagram of atomic absorption instrument.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

6. Fig. 17.5. Design of hollow-cathode lamp.
The hollow cathode is constructed of the test element.
Atomic vapor is produced which is excited and emits the lines of the element.
Fig Design of hollow-cathode lamp.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

7. Fig. 17.6. Design of electrodeless discharge lamp
In an EDL, a radiofrequency generates an intense electromagnetic field, creating an inductively coupled discharge, and emission of the characteristic lines of the element.
It is most useful for the more volatile elements, like As, Cd, Hg, Pb, and Tl.
Fig Design of electrodeless discharge lamp

8. Atoms from the flame enter the slotted quartz tube.
The prolonged residence time results in increased signal-to-noise ratio.
Fig Slotted quartz tube put above the flame has a shorter exit slit at an angle, prolonging the residence time of atoms.

9. In ETAAS, the flame is replaced by an electrically heated graphite tube.
A few microliters of sample is placed in the tube.
It is dried and ashed at lower heats, and then vaporized at high temperature.
The atomization efficiency is greater than for a flame, and detection limits are lower.
Fig Left: Photograph of a transversely heated graphite tube with an integrated platform. The light beam passes from left to right; electrical contact is between the front and back. The sample is introduced through the hole at the top directly onto the platform. Courtesy PerkinElmer Inc. Right: A typical electrothermal AAS instrument using a axially heated graphite tube shown schematically.

10. A high pressure xenon lamp as continuum source gives the required high intensity needed since only a small fraction is passed by the high resolution Eschelle spectrometer, which allows atomic resolution.
Fig Continuum source-high resolution spectrometer setup for AAS.

11. Fig. 17.10. An inductively coupled plasma.
The RF coil excites argon gas flowing through the quartz tube, creating a conducting gas, and plasma temperatures reach 10,000 K, making ICP an ideal source for multielement emission spectrometry.
The sample is introduced as a nebulized aerosol, much like sample introduction in a flame.
Fig An inductively coupled plasma.

12. The two switchable view selection mirrors can be positioned to view either the axial or radial emission of the plasma.
Fig The optical layout of the Thermo iCAP 6000, a dual view ICP-OES instrument. The position of the two easily switchable view selection mirrors dictate which view is imaged. Courtesy of Thermo Fisher Scientific.

13. In laser ablation ICP, a high energy UV laser pulse is directed on a the surface of a solid sample, vaporizing the sample spot.
The vapor is carried into an ICP for elemental analysis.
Fig Laser ablation created crater in a ZnS specimen (mineral Sphalerite). The laser ablated crater is approximately 30 m in diameter and 20 m deep. Courtesy Alan E. Koenig, US Geological Survey, Denver, CO.

14. Boosted discharge hollow cathode lamps provide the high intensity needed for sensitive atomic fluorescence measurements.
They are more stable and intense than electrodeless discharge lamps and provide superior results in the UV, e.g., for As and Se at and nm.
Fig Hollow cathode vs. boosted discharge hollow cathode lamp. Courtesy Photron Pty Ltd.

15. Standard additions calibration corrects for matrix effects.
The intercept on the left axis is the analyte amount in the sample.
The sample concentration is calculated from the slope, m, the intercept, b, the sample volume, Vx, and the standard concentration, Cs.
Cx = (-CsVx)(-b/m)
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)