Atomic Fluorescence Spectroscopy (AFS) See also: Fundamental reviews in Analytical Chemistry e.g. Bings, N. H.; Bogaerts, A.; Broekaert, J. A. C. Anal. Chem. 2002, 74, (“Atomic Spectroscopy”) e.g. Bings, N. H.; Bogaerts, A.; Broekaert, J. A. C. Anal. Chem. 2002, 74, (“Atomic Spectroscopy”) Late 1800’s - Physicists observe fluorescence from Na, Hg, Cd, and TlLate 1800’s - Physicists observe fluorescence from Na, Hg, Cd, and Tl Alkemade uses AFS to study chemistry in flames Alkemade uses AFS to study chemistry in flames AFS recognized as an analytical tool AFS recognized as an analytical tool

Fluorescence Skoog, Hollar, Nieman, Principles of Instrumental Analysis, Saunders College Publishing, Philadelphia, Radiative transition between electronic states with the same multiplicity. Radiative transition between electronic states with the same multiplicity. Almost always a progression from the ground vibrational level of the 1 st excited electronic state. Almost always a progression from the ground vibrational level of the 1 st excited electronic state – sec – sec. Occurs at a lower energy than excitation. Occurs at a lower energy than excitation.

Types of Atomic Fluorescence Resonance (a)Resonance (a) Excited State Resonance (b)Excited State Resonance (b) Stokes/Anti-Stokes Direct Line (c-f)Stokes/Anti-Stokes Direct Line (c-f) Stokes/Anti-Stokes Stepwise Line (g-l)Stokes/Anti-Stokes Stepwise Line (g-l) Sensitized (m)Sensitized (m) Two-Photon Excitation (n)Two-Photon Excitation (n) Omenetto, N. and Windfornder, J. D., Applied Spectroscopy, 26(5), 1972,

Instrumentation Sources: HCL, laser (cw or pulsed), ICP, Xe arc lampSources: HCL, laser (cw or pulsed), ICP, Xe arc lamp stablestable extremely high radiance at excitation wavelengthextremely high radiance at excitation wavelength Atomizer: flame, plasma, furnaceAtomizer: flame, plasma, furnace high nebulization/atomization efficiencyhigh nebulization/atomization efficiency high excitation efficiencyhigh excitation efficiency for flame, minimize quenching (Ar<H 2 <H 2 O<N 2 <CO<O 2 <CO 2 )for flame, minimize quenching (Ar<H 2 <H 2 O<N 2 <CO<O 2 <CO 2 ) Wavelength Selection: monochromator, filtersWavelength Selection: monochromator, filters low dispersion monochromator or filter with line sourcelow dispersion monochromator or filter with line source Detector: PMTDetector: PMT

ICP-AF Spectrometer Ingle and Crouch, Spectrochemical Analysis

LODs for AFS Ingle and Crouch, Spectrochemical Analysis