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BackgroundBackgroundCo-Op research in college - Characterization of water soluble
polymers
PhD 1997, UF - Atomic Spectroscopy“Resonance Ionization Spectroscopy for the Ultratrace
Detection of Mercury”
1997-2001Teaching, Undergraduate Research
2001-2004, Pfizer - Method Development for Drugs in Clinical Trials - esp. HPLC
Co-Op research in college - Characterization of water soluble polymers
PhD 1997, UF - Atomic Spectroscopy“Resonance Ionization Spectroscopy for the Ultratrace
Detection of Mercury”
1997-2001Teaching, Undergraduate Research
2001-2004, Pfizer - Method Development for Drugs in Clinical Trials - esp. HPLC
Instrumental Analysis - things to keep in mind, or to question.
Instrumental Analysis - things to keep in mind, or to question.
Why do we do it that way?
Why can’t we use this for that?
Accuracy, LOD, acquisition time, S/NTechnological Advances
Examples: Home Pregnancy Tests, RP HPLC
Why do we do it that way?
Why can’t we use this for that?
Accuracy, LOD, acquisition time, S/NTechnological Advances
Examples: Home Pregnancy Tests, RP HPLC
Is Light a Wave or a Particle? It’s both.Is Light a Wave or a Particle? It’s both.
Wave nature of light:
c = in a vacuum
Light travels in a wavec = 2.998 x 108 m/s
Particle nature of light:
E = hThe energy of light is quantized - light travels in packets
of energy called photonsh = 6.626 x 10-34 J·s 1 eV = 1.602 x 10-19J
Wave nature of light:
c = in a vacuum
Light travels in a wavec = 2.998 x 108 m/s
Particle nature of light:
E = hThe energy of light is quantized - light travels in packets
of energy called photonsh = 6.626 x 10-34 J·s 1 eV = 1.602 x 10-19J
UnitsUnitsUnits
What makes a method spectrometric?
What makes a method spectrometric?
Interaction between radiation and matter.
Includes beams of particles.
Interaction between radiation and matter.
Includes beams of particles.
Review of Wave Properties of LightReview of Wave Properties of Light
= 2.998 x 108 m/s
What happens to traveling light waves?Behavior of Light Waves
What happens to traveling light waves?Behavior of Light Waves
Transmission:Transmission: Light traveling through a medium
c = v
v = velocity of light (= c in a vacuum) = refractive index of media >1, light travels slower through media
v = when light is traveling through a medium, it slows down, the wavelength changesFrequency is a fundamental property of radiation - doesn’t change based on medium.
Transmission:Transmission: Light traveling through a medium
c = v
v = velocity of light (= c in a vacuum) = refractive index of media >1, light travels slower through media
v = when light is traveling through a medium, it slows down, the wavelength changesFrequency is a fundamental property of radiation - doesn’t change based on medium.
Behavior of Light WavesBehavior of Light WavesDiffraction:Diffraction: Light is bent when it encounters
an obstacle
as it passes a sharp barrier
or through a narrow opening (slit).
Diffraction:Diffraction: Light is bent when it encounters an obstacle
as it passes a sharp barrier
or through a narrow opening (slit).
Coherent radiation: waves have same frequency and remains in phase. Example: laser.Incoherent radiation: Example: light bulb (W filament)
Diffraction is a consequence of Interference.
Diffraction PatternDiffraction Pattern
Behavior of Light WavesBehavior of Light WavesInterference: waves of same frequency (coherent)
experience interference.Interference: waves of same frequency (coherent)
experience interference.
ConstructiveAdd together - bright spots
in diffraction pattern
DestructiveCancel each other out -
dark spots in diffraction pattern
Polychromatic interferenceexamples
Polychromatic InterferencePolychromatic Interference
Behavior of Light WavesBehavior of Light Waves
Reflection and Refraction
Refraction: Reflection:Snell’s law, 1600’s
Reflection and Refraction
Refraction: Reflection:Snell’s law, 1600’s
sin 1 = v1 = 1 sin 2 = v2 = 2
Ir = ( 2 - 1) I0 ( 2 + 1)
Ibn Sahl
~1000 AD
Ibn Sahl
~1000 AD
Behavior of Light WavesBehavior of Light Waves
Polarization
With a polarizing filter, you can remove reflected light (“noise”) from your picture (“signal”)
Polarization
With a polarizing filter, you can remove reflected light (“noise”) from your picture (“signal”)
Particle Nature: The Photoelectric Effect
Particle Nature: The Photoelectric Effect
Heinrich Hertz, 1887
Albert Einstein, 1905
Millikan, 1916
Heinrich Hertz, 1887
Albert Einstein, 1905
Millikan, 1916
a.k.a. Opto-Galvanic effect
How light interacts with matterHow light interacts with matter
AbsorptionAn atom or molecule absorbs a photon of energy and
is excited from the ground state.
Emission and LuminescenceAn excited atom or molecule is unstable, returns to the
ground state and gets rid of the excess energy by emitting a photon
ScatteringPhotons bounce off of particles, either elastically (photon retains same E) or inelastically (change in E)
AbsorptionAn atom or molecule absorbs a photon of energy and
is excited from the ground state.
Emission and LuminescenceAn excited atom or molecule is unstable, returns to the
ground state and gets rid of the excess energy by emitting a photon
ScatteringPhotons bounce off of particles, either elastically (photon retains same E) or inelastically (change in E)
Energy States of Chemical Species
Energy States of Chemical Species
The particle theory of light explains spectra in terms of energy states. We use the spectra to tell us something about the chemical species present in our sample.
The particle theory of light explains spectra in terms of energy states. We use the spectra to tell us something about the chemical species present in our sample.
Energy State DiagramsEnergy State DiagramsOn the left is a diagram of an
atom (Na)
On the right is a diagram for a simple molecule
On the left is a diagram of an atom (Na)
On the right is a diagram for a simple molecule
Spectra
Least complex
Morecomplex
Applications of EM regionsApplications of EM regionsRadiation Frequency
(Hz)Wavelength Transition Non-Chemical
Uses
Radio < 3x1011 >1 mm nuclear spin flips
SignalTransmission
MW 3x1011-1013 1 mm-25 um molecular rotations, electron spin flips
Cooking
IR 1013-1014 25 um-2.5 um molecular vibrations
Heating
VIS 4-7.5x1014 750 nm-400 nm
valence electron
Illumination
UV 1015-1017 400 nm-1 nm valence electron
"Black" Lights
X-Ray 1017-1020 1 nm-1 pm inner electron Imaging
Gamma 1020-1024 <10-12 m nuclear Cancertreatment
How we do quantitative analysis with spectroscopy
How we do quantitative analysis with spectroscopy
Type Radiant Power Measured
Concentration Relationship
Method
Emission Emitted, Pe Pe = kc Atomic Emission
Luminescence Luminescent, PL PL = kc Atomic and molecular fluorescence,phosphorescence,
chemiluminescence
Scattering Scattered, Psc Psc = kc Raman scattering,turbidimetry,and nephelometry
Absorption Incident, Po & transmitted P
-logP/Po = kc Atomic and molecular absorption