Transcript Document

Atomic Absorption
Terry A. Ring
Chemical Engineering
University of Utah
E= -13.6 eV Z2/n2
Photo absorption/emision
Atomic Absorption
Lamps are Special
• Cathode with
receptacle for material
• Vapor of Material to be
analyzed
• Vapor Excited by
plasma
• Light of particular
wavelength
Aerosol Flow
• Burner Fuel (&
oxidizer) mixed
with aerosol of
sample
• Sample asperated
into burner
• Flame ionizes
Sample
Intensity vs Wavelength in AA
• Light Source
• Absorbance
• Monochromatic
• Detector
Analysis
• Absorption of Light
• Electrons are
excited
• Light Intensity on
detector is less
Graphite furnace AA
Other AA’s
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Flame
Spark
Arc
Plasma
Laser
X-ray
Atomic Emission Spectroscopy
• Flame is used to
generated Atoms
with excited
electrons and ions
• Light is filtered in
spectrometer to give
Intensity vs
wavelength
Spectrometer
• Emitted Light
• Broken into
different color
components
– Prism
– Grating
X-ray Fluorescence
• Two Steps
– Absorption of X-ray
• Elimination of
electron for k or L
shell
– Collapse of M shell
electron to fill hole
• Light emission (xray)
Potential X-ray Emissions
• From K shell hole
– K, K, K,
– Zeeman Effect - 1,
2, 3
• From L shell hole
– L, L, L,
Generation of X-rays
• High Voltage
Electrons
• Electron Scattering
• Electron Absorption
– X-ray photo
ionization
XRF
• Energy-dispersive
XRF
• Wavelengthdispersive XRF
XRF Detectors
• Energy-dispersive
XRF
– Semiconductor
• Wavelength
dispersive XRF
– Scintilation Counter
XRF Analysis
• Samples can be in
any form
– Solid
– Powder
– Liquid