1. OPTICAL ATOMIC SPECTROMETRY Chap 8 Three major types Optical spectrometry Optical spectrometry Mass spectrometry Mass spectrometry (X-ray spectrometry) (X-ray spectrometry) In all three, atoms or ions are atomized

2. ENERGY LEVEL DIAGRAMS Sodium “D-lines” at 589.6 and 590.0 nm SHC, 6e, Fig. 8-1 (a)

3. Electronic States SHC, 6e, Fig. 8-3 Ground state Singlet of Mg atom 3s For a molecule

4. Absorption, emission, and fluorescence by atoms in a flame.

5. Profile of an Atomic Linewidth SHC, 6e, Fig. 8-6 Signal Δλ 1/2 = FWHM λ0λ0 FWHM ≡ Full Width at Half Maximum

6. SOURCES OF LINE BROADENING (in order of increasing effect) (1)Uncertainty Effect (Natural Linewidths)  Δ ν · Δt > 1  Because excited state lifetimes (t) are brief ( ∼ ns – μs), the uncertainty (Δt) is small and ∴ Δ ν is relatively large (2)Doppler Broadening  Wavelength shift caused by motion of atoms relative to detector

7. The Doppler Effect Analogous to SHC, 6e, Fig. 8-7 Blue shift Red shift

8. (3)Pressure Broadening (Collisional Broadening)  Collisions cause small changes in ground state energy levels (i.e., smearing)  Δλ 1/2 >> Δλ 1/2 of isolated atom  At high pressures  continuum radiation  e.g., high-pressure Hg and Xe lamps

9. TEMPERATURE EFFECT ON ATOMIC SPECTRA Effect described by Boltzmann distribution Effect described by Boltzmann distribution j 0 ooooooooooooooooooo oooooo P ≡ degeneracy of level

10. TEMPERATURE EFFECT ON ATOMIC SPECTRA At low T j 0 ooooooooooooooooooo ooo At high T 0 j ooooooooooooo ooooooooo

11. SAMPLE INTRODUCTION METHODS Common Types of Atomizers (from SHC, 6e, Table 8-1) Flame1700 – 3100 °C Flame1700 – 3100 °C Electrothermal (“furnace”)1200 – 3000 °C Electrothermal (“furnace”)1200 – 3000 °C Inductively coupled plasma (ICP)4000 – 6000 °C Inductively coupled plasma (ICP)4000 – 6000 °C Electric arc 4000 – 5000 °C Electric arc 4000 – 5000 °C (e.g., Vreeland spectroscope)

12. SHC, 6e, Fig. 8-6 Processes leading to sample atomization

13. INTRODUCTION OF SOLUTION SAMPLES Nebulization: sample is aspirated (“sucked in”) and converted to fine mist or aerosol Nebulization: sample is aspirated (“sucked in”) and converted to fine mist or aerosol Pneumatic Pneumatic Ultrasonic Ultrasonic Hydride generation (for species of low volatility, e.g., Hg, Pb, Se, Sb, etc.) Hydride generation (for species of low volatility, e.g., Hg, Pb, Se, Sb, etc.) INTRODUCTION OF SOLID SAMPLES Electrothermal (introduces and vaporizes sample) Electrothermal (introduces and vaporizes sample) Arc Ablation Arc Ablation

14. SHC, 6e, Fig. 8-11 Pneumatic nebulizers