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