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CHM 5175: Part 2.4 Other Absorption Techniques 1 Sourc e hn Sample Detecto r Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00
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CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Dec 23, 2015

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Page 1: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

1

CHM 5175: Part 2.4Other Absorption Techniques

Sourcehn

Sample

Detector

Ken HansonMWF 9:00 – 9:50 am

Office Hours MWF 10:00-11:00

Page 2: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

2013 Nobel Prize in Chemistry

Page 3: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

1998 Nobel Prize in Chemistry

Page 4: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

2013 Nobel Prize in ChemistryDEVELOPMENT OF MULTISCALE MODELS

FOR COMPLEX CHEMICAL SYSTEMS

Page 5: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

DEVELOPMENT OF MULTISCALE MODELS FOR COMPLEX CHEMICAL SYSTEMS

2013 Nobel Prize in Chemistry

Page 6: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

DEVELOPMENT OF MULTISCALE MODELS FOR COMPLEX CHEMICAL SYSTEMS

2013 Nobel Prize in Chemistry

Page 7: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

2013 Nobel Prize in Chemistry

Page 8: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

8

CHM 5175: Part 2.4Other Absorption Techniques

Sourcehn

Sample

Detector

Ken HansonMWF 9:00 – 9:50 am

Office Hours MWF 10:00-11:00

Page 9: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Sourcehn

Sample

Detector

1) Circular Dichroism 2) Infrared Spectroscopy

Content

Page 10: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Sample

Detector

End View

UV-Vis Spectroscopy

Unpolarized Light

Page 11: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarizers

Page 12: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization of Light

Side View End View

Vertically Polarized

Horizontally Polarized

http://www.enzim.hu/~szia/cddemo/edemo0.htm

Page 13: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

S

S

C6H13

C6H13

Light + MoleculesSource

Strong Absorption

Weak Absorption

Page 14: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Orientation Dependent Absorption

Ph

Ph

Angew. Chem. Int. Ed. 2005, 44, 6564 –6568

a axis

b axis

Page 15: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization of Light

Side View End View

Vertically Polarized

Horizontally Polarized

http://www.enzim.hu/~szia/cddemo/edemo0.htm

Page 16: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Adding Polarized LightIn phase (peak at the same time) + same amplitude

Vertical + Horizontal = 45° diagonal

Page 17: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Adding Polarized Light

Green peaks when red baselines.Sum (blue) is always 1.

¼ l (90°) out of phase + same amplitude

Vertical + Horizontal = Circular

Page 18: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

l/4 Wave Plate Polarizer

l/4 Wave Plate Polarizer

Page 19: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization of Light

Side View End View

left-circularly polarized

right-circularly polarized

Page 20: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Adding Polarized LightIn phase (peak at the same time) + same amplitude

left circular + right circular = vertical

Green peaks when red peaks.

Page 21: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Absorption Spectroscopy

Absorbance: A = -log T = log P0/P

P0

(power in)

P

(power out)

P0

P

Page 22: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chiral Molecules

Page 23: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

The Beer-Lambert Law:

A = absorbance (unitless, A = log10 P0/P)

e = molar absorptivity (L mol-1 cm-1)

l = path length of the sample (cm)

c = concentration (mol/L or M)

A = e c l e is the same for D and LIf C are equal:

50:50 D to L100% D100% L

Then A is the same.

Assuming the light is unpolarized!

Absorption Spectroscopy

Page 24: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

P0

(power in)

P

(power out)

left-circularly polarized

right-circularly polarized

Circular Absorption

Absorbs moreSmaller P

Absorbs LessLarger P

Page 25: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Circular Absorption

Absorbance: A(left) = log P0(left) /P(left)

A(right) = log P0(right)/P(right)

P0

(power in)

P

(power out)

P0(left)

P(left)

Page 26: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarizer

Prism

Source

Circular Dichroism

Process:1) Unpolarized white light2) Monochrometer3) Plane polarizer4) left-right modulator5) left (then right) through sample6) measure P for right (then left) through sample

Page 27: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Circular DichroismCD measures the difference between the absorption of left and right handed cirularly-polarized light:

De is typically <10 M-1 cm-1

e is typically > 10,000 cm-1

= 3298 Δε.

CD spectra reported in ellipticity () or De

e in L/mol cm (liters mol-1 centimeters-1) in degrees cm2/dmol-1 (degrees centimeters2 decimol-1)

Page 28: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Spectra

Absorption Circular Dichroism

Page 29: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

CD Spectrometer

AVIV 202 CD spectrometerInstitute of Molecular Biophysics

170-875 nm

-10oC to 110oC

titrator attachment

Page 30: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

• Determination of secondary structure of proteins• Investigations of protein-protein interactions• Investigation of the effect of drug binding• Protein structure in a membrane• Stereoselective synthesis• Dynamic processes

- protein folding- reaction dynamics• DNA denaturation

Applications

GCN4-p1 coiled–coil

Page 31: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

CD End

Any Questions?

Page 32: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Sourcehn

Sample

Detector

1) Circular Dichroism 2) Infrared Spectroscopy

Content

Page 33: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

250 300 350 400 450 500 550 6000

2

4

6

8

10

(10

4 M

-1cm

-1)

Wavelength (nm)

Visible: 300-700 nm / 30,000-14,000 cm-1

Mid-IR: 2,500-15,000 nm / 4,000-650 cm-1

2(PF6)

N

N

Ru

2

t-Bu

t-Bu

Mojet et al. Chem. Soc. Rev. 2010, ASAP.

OH H

O H

Spectroscopy

Page 34: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Infrared Spectroscopy

Page 35: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Kincaid et al. J . Phys. Chem. 1988, 92, 5628.

2Cl

N

N

Ru

2

C2v: 20A1 + 19B2 + 9B1

2Cl

N

N

Ru

2

D

D

2Cl

N

N

Ru

2

D

D

2Cl

N

N

Ru

2

D

DDD

DD

D

Infrared Spectroscopy

Page 36: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

• Identification of inorganic compounds and organic compounds• Identification of components of an unknown mixture • Analysis of solids, liquids, and gasses• Component quantification• In measurement and analysis of Atmospheric Spectra• Can also be used on satellites to probe space

Applications

Page 37: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Detector

Infrared Spectroscopy

?

Procedure

Step 1: Prepare a sample

Step 2: ???

Step 3: Obtain spectra (Profit!)

Page 38: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Friedrich Wilhelm HerschelAstronomer

Sun

Infrared H2O

Thermometers

Infrared Spectroscopy

Discovered: Uranus Infrared light

(1800)

Page 39: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Detector

Infrared Spectroscopy

?

Infrared Spectroscopic Techniques– Direct Transmission

– Reflection Absorption (RAIRS or IRRAS)

– Polarization-Modulated RAIRS

– Diffuse Reflectance

– Photoacoustic

– Attenuated Total Reflectance

Page 40: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Direct Transmission

Bruker 80v

SampleDetector

Sources

Page 41: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Diode Detector

Direct Transmission

KBr Pellet

Pros:

Simple

Standard

Inexpensive

Cons:

In KBr

No solvent

No surfaces

Boring?

Page 42: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

4000 3500 3000 2500 2000 1500 1000 5000.00

0.01

0.02

0.03

0.04

0.05

0.06

% T

ransm

itta

nce

Wavenumbers (cm-1)

C CC N

C O

P OP O

C H

C H

O H

NN

NN

N

NRu

P

PO

O

O

O

O

O

TiO

2

IR Source

hn

Diode Detector

Direct Transmission

Page 43: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Reflection Absorption (RAIRS)AKA: IRRAS, grazing angle IR

From IR SourceTo Detector

Reflective surface

OP

O

O R

OP

O

O R

OP

O

O R

Requirements– Highly Reflective

Metals, glass, semiconductor

– Planar– Typically monolayers

Disadvantages– Weak Signal (<2% DT)– No solvent– Accessory

Page 44: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Seagull (Harrick Scientific)

Reflection Absorption (RAIRS)

Sample

Page 45: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization Modulation-RAIRS

Reflective surface

s

S-polarized light phase shifts by 180°P-polarized light phase shifts by 90°

(at 80° incident angle)

Page 46: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization Modulation-RAIRS

Reflective surface

S-polarized (180° shift) is destructive-does not contain information about the interface

P-polarized (90° shift) is non-destructive-does contain information about the interface

OP

O

O R

OP

O

O R

OP

O

O Rs

pp

s

Page 47: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization Modulation-RAIRS

Reflective surface

OP

O

O R

OP

O

O R

OP

O

O Rs

pP(p)

P(s)

P(p) = solvent + surface P(s) = solventP(p) - P(s) = surface

Page 48: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

1

2

3,45

1. Incident light is polarized2. PEM shifts between S and P3. Polarized light hits sample4. At the surface:

-S-polarized signal is nullified-P-polarized signal is enhanced

5. Light hits the detector6. P(p) - P(s) = surface spectrum

Polarization Modulation-RAIRS

Page 49: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

RAIRS

PM-RAIRS

Paniagua et al. J. Phys. Chem. C 2008, 112, 7809.

PM-RAIRS vs RAIRS

Glass SlideITO

IR activeO

PO

O

OP

O

O

OP

O

O

R R R

IR inactive

Page 50: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Pros:Can use solvent

Suggests orientation

Sensitive

Cons:Expensive (>$200,000)

Requires reflective surface

Planar surface

Glass SlideITO

IR activeO

PO

O

OP

O

O

OP

O

O

R R R

IR inactive

Polarization Modulation-RAIRS

Page 51: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Diffuse Reflectance (DRIFTS)

Factors for Scatter-Particle Size

50 mm or less-Refractive Index-Depth

>1.5 mm

Page 52: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Ellipsoidal Reflector Integrating Sphere

Diffuse Reflectance (DRIFTS)

SampleIncident

lightDetector

Page 53: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Diffuse Reflectance (DRIFTS)

Pros:Can measure scattering samples

Accessory

Inexpensive

Cons:Need a scattering sample

No solvent

Not as sensitive

Pike EasiDiff Pike AutoDiff

Page 54: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Detector

Infrared Spectroscopy

?

Infrared Spectroscopic Techniques– Direct Transmission

– Reflection Absorption (RAIRS or IRRAS)

– Polarization-Modulated RAIRS

– Diffuse Reflectance

– Photoacoustic

– Attenuated Total Reflectance

Page 55: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

2013 Nobel Peace Prize

http://www.opcw.org/

The Organisation for the Prohibition of Chemical Weapons (OPCW) is an intergovernmental organisation, located in The Hague, Netherlands. The organisation promotes and verifies the adherence to the Chemical Weapons Convention which prohibits of the use of chemical weapons and requires their destruction. The verification consists both of evaluation of declarations by members states and on-site inspections

“The said interest shall be divided into five equal parts, which shall be apportioned as follows: /- - -/ one part to the person who shall have done the most or the best work for fraternity between nations, the abolition or reduction of standing armies and for the holding and promotion of peace congresses.”

Page 56: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Member Statesthat have signed and ratified or acceded to the Chemical Weapons Convention, an international agreement outlawing the production, stockpiling and use of chemical weapons.

Page 57: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Member States

Page 58: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Members

6 states are non-members: Angola, Burma, Egypt, Israel, North Korea and South Sudan.

“one part to the person who shall have done the most or the best work for fraternity between nations”

Page 59: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical WarfareAll modern warfare is chemical warfare

Damascus steel

eighth century A.D.

ReiboldM., et al. Nature, 444. 286 (2006)

Page 60: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical WarfareAll modern warfare is chemical warfare

10 KNO3 + 3 S + 8 C → 2 K2CO3 + 3 K2SO4 + 6 CO2 + 5 N2

Page 61: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical Warfare

Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from nuclear warfare and biological warfare, which together make up NBC, the military acronym for nuclear, biological, and chemical (warfare or weapons), all of which are considered "weapons of mass destruction" (WMD). None of these fall under the term conventional weapons which are primarily effective due to their destructive potential.

Conventional Weapons- small arms and light weapons, sea and land mines, as well as (non-nuclear) bombs, shells, rockets, missiles and cluster munitions.

Page 62: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical Warfare

Page 63: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Harassing AgentsThese are substances that are not intended to kill or injure. They are often referred to as Riot Control Agents (RCAs) and may be used by civilian police forces against criminals and rioters, or in the military for training purposes. In general, harassing agents are sensory irritants that have fleeting concentration dependent effects that resolve within minutes after removal. Casualty effects are not anticipated to exceed 24-hours nor require medical attention.

Chemical Warfare

Page 64: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical Warfare

NH33H2 + N2 2

Arguably the highest impact innovations of the twentieth century: without it, 50% of the world’s population would not be here.

Fritz Haber1868-1934

Nobel in 1918

He has also been described as the "father of chemical warfare" for his work developing and deploying chlorine and other poisonous gases during World War I.

Page 65: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Gas warfare in World War I was, in a sense, the war of the chemists, with Haber pitted against French Nobel laureate chemist Victor Grignard.

Regarding war and peace, Haber once said, "During peace time a scientist belongs to the World, but during war time he belongs to his country."

This was an example of the ethical dilemmas facing chemists at that time.

Chemical Warfare

Page 66: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Chemical Warfare

Who is making these chemicals?

Who is optimizing their performance?

Page 67: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Research Ethics

Manhattan Project

$26 billion130,000 people

If given unlimited resources to work on the biggest engineering, physics and chemistry problem in the history

of the world, would you do it?

What if it might be used to vaporize 300,000 humans in an instant?

Page 68: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Deuterated Solvents Isotopic Labeling

Byproducts

Nuclear Reactors Large Hadron Colliders

Page 69: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

One row of visible pixels

Two rows of n-IR pixels IR monocular which replaces

infrared emission with green

Visible Image

Near Infrared OLED Screen

Create a molecules (and an OLED) that efficiently emits between 750 – 900 nm.

Department of Defense

N

N

N

N

Pt

Page 70: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Create a organic detector array that can monitor between 300-1700 nm.

Focusing Lens

Organic photodiode arrayanodeorganicscathode

Hemispherical

Focal Plane

Readout circuit

Object

N N

NN

N N

NNZn Zn

Ar Ar

ArAr

C60

GlassITO

Fused Dimer

AgAgAgBCP

Defense Advanced Research Projects Agency

Page 71: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Ethics questions

Would you have worked on the Manhattan Project?

Will you work for the DOD, DARPA, AFOSR…?

Page 72: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Detector

Infrared Spectroscopy

?

Infrared Spectroscopic Techniques– Direct Transmission

– Reflection Absorption (RAIRS or IRRAS)

– Polarization-Modulated RAIRS

– Diffuse Reflectance

– Photoacoustic

– Attenuated Total Reflectance

Page 73: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Polarization Modulation-RAIRS

Reflective surface

S-polarized (180° shift) is destructive-does not contain information about the interface

P-polarized (90° shift) is non-destructive-does contain information about the interface

OP

O

O R

OP

O

O R

OP

O

O Rs

pp

s

90° shift0° shift 180° shift

= 0f = 90°f = 180°f

Page 74: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Constructive/Destructive Interference

Page 75: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Light

Sample Thermal Wave

Carrier Gas

Det

ecto

r

1. Incident light2. Absorbed by sample3. Optical to thermal energy4. Heat wave through sample5. Thermal-expansion-driven

pressurization in the gas6. Wave hits the detector

-Microphone-piezoelectric transducer

Photoacoustic IR Spectroscopy

Page 76: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

N3

N719

N712

Gratzel et al. J. Phys. Chem. B 2003, 107, 8981.

N

N

NCS

NCS

N

N

Ru

COOH

HOOC

HOOC

COOHN3

Photoacoustic IR Spectroscopy

Page 77: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Pros:Neat Solids

Depth Profiling

Cons:8 cm-1 resolution

No solvent

Specialty Equipment

Photoacoustic IR Spectroscopy

Page 78: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Attenuated total reflection (ATR-IR)

Evanescent wave

Page 79: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Wavelength

Refractive index crystal (n1) sample (n2)

Angle of incidence

Penetration depth

n1

n2

n1 *dp

(mm) pH Range LWL, cm-1

AMTIR 2.5 1.46 1-9 625Diamond/ZnSe 2.4 1.66 1-14 525Diamond/KRS-5 2.4 1.66 1-14 250

Germanium 4 0.65 1-14 780KRS-5 2.37 1.73 5-8 250Silicon 3.4 0.84 1-12 1500

Silicon/ZnSe 3.4 0.84 1-12 525ZnS 2.2 2.35 5-9 850

ZnSe 2.4 1.66 5-9 525*dp based on n2 = 1.5, Θ = 45°, λ = 1000 cm-1

Attenuated total reflection (ATR-IR)

Page 80: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Attenuated total reflection (ATR-IR)

Single Reflection Multiple Reflection

Incident light

Detector

Page 81: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

TiO2

Pressure

TiO2

Pressure

Multi ATR

Single ATR

vs

Single vs Multi ATR

Page 82: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Attenuated total reflection (ATR-IR)

Multiple ReflectionSingle Reflection

Page 83: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

TiO2

Z-955Glass Slide

C-9 alkyl chain- 2856, 2926, 2959 cm-1

Bipyridine- 1398, 1548, 1615 cm-1

PO3H2- 952, 1060, 1151 cm-1

SCN- 2104 cm-1

N

N

NCS

NCS

N

N

Ru

PO3H2

H2O3P

C9H19

C9H19

C HSCN

C C

C N

PO3H2

Gratzel et al. J. Phys. Chem. B 2004, 108, 17553.

TiO2

Glass Slide

Diamond

Source Detector

Single Reflection

Attenuated total reflection (ATR-IR)

Page 84: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Rivera et al. Langmuir 2010, 26, 5534.

• ZnSe Crystal (50 x 10 x 2 mm)

• Coat with TiO2

• Molecule + Water (pH 3.5/HCl)

• Monitor adsorption vs concentration

SOO

ONa

n

TiO2

Water + Polymer

ZnSeConcentration

asym SO3sym SO3

C C C C

Attenuated total reflection (ATR-IR)

Page 85: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

Pros:Solids/powders/solutions

Solid-solution interface

External stimuli

No prep time

Accessory

Monitor kinetics

Cons:Pressure sensitive

Less resolution

Crystals are expensive

Attenuated total reflection (ATR-IR)

Page 86: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

IR Source

hn

Sample

Detector

Infrared Spectroscopy

?

Infrared Spectroscopic Techniques– Direct Transmission

– Reflection Absorption (RAIRS or IRRAS)

– Polarization-Modulated RAIRS

– Diffuse Reflectance

– Photoacoustic

– Attenuated Total Reflectance

Page 87: CHM 5175: Part 2.4 Other Absorption Techniques 1 Source h Sample Detector Ken Hanson MWF 9:00 – 9:50 am Office Hours MWF 10:00-11:00.

ATR-IR End

Any Questions?