The Challenges and Opportunities of The Challenges and Opportunities - - PowerPoint PPT Presentation

2006 International Conference on Nanotechnology, April 26-28, 2006 Atlanta, GA

The Challenges and Opportunities of The Challenges and Opportunities of Measuring Properties of Nanoparticles Measuring Properties of Nanoparticles and Nanostructured Materials: and Nanostructured Materials:

Importance of a Multi Importance of a Multi-

• Technique Approach

Technique Approach

• D. R. Baer, M. H. Engelhard, C
• D. R. Baer, M. H. Engelhard, C-
• M. Wang, A. S. Lea, K.
• M. Wang, A. S. Lea, K. Pecher

Pecher

Presented by:

Donald R. Baer

Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory

Your logo here

Four Messages Four Messages

1. Adequate characterization frequently requires an integrated multi integrated multi-

• technique approach

technique approach 2. For fundamental reasons nano-structured materials are a challenge to characterize. challenge to characterize. 3. 3. Routine sample handling, data collection, and analysis Routine sample handling, data collection, and analysis approaches may not be satisfactory approaches may not be satisfactory – near state of the art data analysis, data modeling, and use of information from other methods can be important. 4. 4. Exciting opportunities Exciting opportunities – There are many new methods, major advances in older methods, and new approaches to data analysis. Use all resources available including User

Facilities (including National Labs) and recommended practices (ASTM and ISO).

• Scanning Tunneling Microscopy

Nobel Prize in Physics in 1986

• Supramolecular Chemistry

Nobel Prize in Chemistry 1987

• Ion Trap

Nobel Prize in Physics 1989

• Fullerenes or “Buckeyballs”

Nobel Prize in Chemistry 1996

• Molecular Tweezers

Nobel Prize in Physics 1997

Nanoscience Related Nobel Prizes Nanoscience Related Nobel Prizes

Imaging & Manipulating Matter Imaging & Manipulating Matter

V Vx

x V

Vy

y

V Vz

z

V VT

T

I IT

T

Pt on TiO Pt on TiO2

(anatase anatase) )

Pt Pt nanoclusters nanoclusters on

• n anatase

anatase

Control Control Unit Unit

V Vx

x V

Vy

y

V Vz

z

V VT

T

I IT

T

Pt on TiO Pt on TiO2

(anatase anatase) )

Pt Pt nanoclusters nanoclusters on

• n anatase

anatase

Control Control Unit Unit

The rapid development of nanoscience and nanotechnology has been fueled by several discoveries and the development of computational and experimental tools. We have many wonderful tools for handling and examining nano-structures. One of the greatest impacts has been the visualization and measurements at the atomic level enabled by scanning probe microscopy methods.

“Which way is the men’s room?”

We have tools to obtain lots of very useful and important information. However, are the tools we have capable and being used to provide the information we need?

Four Messages Four Messages

• 1. Adequate characterization frequently

requires an integrated multi integrated multi-

• technique approach

technique approach

2. For fundamental reasons nano-structured materials are a challenge to characterize. challenge to characterize. 3. 3. Routine sample handling, data collection, and analysis Routine sample handling, data collection, and analysis approaches may not be satisfactory approaches may not be satisfactory – near state of the art data analysis, data modeling, and use of information from other methods can be important. 4. 4. Exciting opportunities Exciting opportunities – There are many new methods, major advances in older methods, and new approaches to data analysis.

Possible use of iron nanoparticles to assist environmental remediation one research area driving analysis needs

HCOOH, CO, etc.

CCl4 (CT)

• CCl3

HCCl3 (CF)

+1 e-

• 1 Cl-

+•H +1 e-

• 1 Cl-

:CCl2

Toxic Breakdown Products

Benign Breakdown Products

• Transmission Electron Microscopy – Size, structure, shape
• X-ray Photoelectron Spectroscopy – Surface Chemistry; Composition;

Contamination

• Surface Area – Gas Adsorption - BET
• XRD – Structure, Grain Size
• Reaction Studies and Electrochemical Measurements
• X-ray adsorption Spectroscopy - electronic structure, oxidation state, property

variation

• Modeling – Structure, Transport Properties

Nano Particle Handling Nano Particle Handling

• HRTEM/TEM

Samples processed in methanol, TTFE or water, dried and transported to TEM in air. Samples mounted on TEM grid with no processing and transported to TEM in air.

• XRD

Dried in glove box and packed into XRD mount. Samples coated with glycerol and mounted on TEM grid.

• XPS

Mounted in glove bag and loaded into Vacuum system without exposure to air.

• STXM

Mounted in air on TEM grid

• Electrochemistry and Kinetic (batch studies)

Glove box dried. Flash Dried using methanol and vacuum system.

Toda Nano Iron FeH2 Zhang Nano Iron FeBH

5 nm 5 nm

Mostly Fe0 20 to 60 nm spheres with boron oxide rich coating and made up of <1.5 nm grains. Assembled into larger aggregates Two phase system: 30-60 nm Fe0 particles with oxide shell/coating and made up of ∼ 30 nm grains and 30-100 nm Fe3O4 particles. Also collected into aggregates.

Summary of Two Particle Types

Name Particle Size Surface Area Major Minor Diameter [m2/g] Phase Phase FeH2 70 nm 29 [4-60] α

• Fe0

Magnetite FeBH 10-100nm 33.5 Fe0 Goethite FeEL 150 mm 0.1-1 99% Fe0

Supplier claims

Name Particle Size Surface Area Major Minor Diameter [nm] [m2/g] Phase Phase TEM BET FeH2 ∼ 40 nm 3.5 3 Fe0/Magnetite Oxide shell FeBH ∼ 60 [20-100]nm 7-8.5 5 Fe0 Boron oxide coating FeEL 150 mm 0.15 Fe0

Our Measurements

Material size and surface areas

Results of Synthesis or Processing: size and size distribution composition and structure component segregation surface contamination defect concentration shape

Information needed about nano Information needed about nano-

• structured materials?

structured materials?

Experimental Axes

• Energy; Composition;

Spectroscopy; Structure

• Resolution; Dimension;

Position 2 Dimensional Analysis Composition Position

Results of Synthesis or Processing: size and size distribution composition and structure component segregation surface contamination defect concentration shape

Information needed about nano Information needed about nano-

• structured materials?

structured materials?

Analyses are usually done assuming that the properties are independent of time and environment.

Influence of History, Aging (Time) and Environment: processing aggregation and growth environmental interactions reactive layer formation structure changes with time

Experimental Axes Change to Multi Dimensional Analysis

• Energy/composition
• Resolution/Dimension
• Time
• Environment

Multi Axis Analysis from Bob Hwang BNL

700 705 710 715 720 725 730 735 740 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Binding Energy (eV) Normalized Intensity

Fe2O3 20 nm particles collected on Au coated Si substrate as received and after 2 kV Ar+ ion sputter (2 nm for SiO2)

Significant reduction of particles As deposited Sputtered

Ion Beam Damage of Nano Particles

Fe2O3 film on Al2O3 as received and after 2 kV Ar+ ion sputter (3 nm for SiO2)

700 705 710 715 720 725 730 735 740 745 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Binding Energy (eV) Normalized Intensity

sputtered

Very little selective sputtering and oxide reduction

Fe 2p photoelectron peaks

We need to understand the impact of particle shape on the information we collect Information needed to answer question: Particle Sizes and Shapes (other data) Model for XPS signals for two systems Electron Inelastic Mean Free Path Lengths

How can we determine if the damage (and sputter rate effects) we see on nanoparticles are really different than those of thin films?

Four Messages Four Messages

1. Adequate characterization frequently requires an integrated multi integrated multi-

• technique approach

technique approach

• 2. For fundamental reasons nano-structured

materials are a challenge to characterize. challenge to characterize. Nanostructures Materials can have Nanostructures Materials can have unexpected behaviors. of unexpected behaviors. of

3. 3. Routine sample handling, data collection, and analysis Routine sample handling, data collection, and analysis approaches may not be satisfactory approaches may not be satisfactory – near state of the art data analysis, data modeling, and use of information from other methods can be important. 4. 4. Exciting opportunities Exciting opportunities – There are many new methods, major advances in older methods, and new approaches to data analysis.

Three (of several) Senses of Nano

• Size and surface area effects

1 nm – 100 nm Fundamental materials properties remain the same but size, shape and surface area alter some behaviors work function, solubility, chemical potential

• Critical Size and Characteristic

Length Scale Interesting or unusual

properties because the size of the system approaches some critical length (includes quantum effects). Many characteristics of material may have normal or nearly normal behavior

• New (Non-extensive) Properties

Systems not large enough to have extensive properties. Particles become effectively polymorphs of “bulk” materials and statistical homogeneity may not be valid.

n = 1 n = 1 n = 3 n = 3 n = 2 n = 2 n = 4 n = 4 n = 5 n = 5

Energy / Energy / (h (h2

2/8ml

/8ml2

2)

) 25 25 16 16 1 1 4 4 9 9

size ≈ ≈ d = correlation length d = range of intermolecular forces

• Kelvin equation for solubility
• Gibbs-Thompson relation for

chemical potential

There are many causes of NANO There are many causes of NANO-

• Size effects. Usually these are not indicated.

Size effects. Usually these are not indicated.

Dynamics, Stability, Environmental Effects and Damage

• Surface diffusion - Flemming Besenbacher Email:

fbe@inano.dk Linderoth et al Phys. Rev. Lett. 78 (1999)

4978

• Structure and stability of nanometric sized particles, M

J Yacaman, JVST B19 (2001) 1091

• Nanotube growth and ion effects – Pulickel Ajayan,

SUNY Albany

• Particle Damage – Sudipta Seal (UCF), Mark

Engelhard (PNNL)

Diffusion of Pt on Pt(110)

Diffusion af Pt på Pt(110)

Linderoth et al Phys. Rev. Lett. 78, 4978 Horch et al., NATURE 398, 134(1999) University of Aarhus Denmark

Interdisciplinary Nanoscience Center at University of Aarhus

Diffusion of Pt on Pt(110)

Diffusion af Pt på Pt(110)

Linderoth et al Phys. Rev. Lett. 78, 4978 Horch et al., NATURE 398, 134(1999) University of Aarhus Denmark

Interdisciplinary Nanoscience Center at University of Aarhus

Nano-Structures Can Be Unstable

et al. HR TEM of Au nanoparticles

Smith et. al., Science 1986, 233, 872

Not a new effect 20 years ago it made Science

P 402

Are fluctuations and stability important?

Nature 424, 1025 - 1029 (28 August 2003); Water-driven structure

transformation in nanoparticles at room temperature,

HENGZHONG ZHANG*, BENJAMIN GILBERT*, FENG HUANG & JILLIAN F. BANFIELD

Nanoparticle Surface and Bulk Structures Can Change With Particle Size, Particle History and Environmental Conditions

Environmental Effect A Different Approach to Nanothermodynamics

Terrell L. Hill, Nano Letters Vol 1 (2001) 273-275

“In contrast to macro-thermodynamics, the thermodynamics of a small system will usually be different in different environments.”

Environmental effects may be fundamental, not accidental

Zhang- the disappearing of the surface Layer with time under electron beam. The Surface layer is amorphous.

Borate shell thickness decreases upon beam exposure

Stability and Probe Effects Stability and Probe Effects -

• Electron Beam Induced Changes

Electron Beam Induced Changes

Contamination, processing history, the environment of the Contamination, processing history, the environment of the measurement, molecular or other capping or measurement, molecular or other capping or passivation passivation may all impact the nature and properties of the may all impact the nature and properties of the nanoparticles. nanoparticles. – These can be very difficult to see or measure and are often ignored. – Sample handling needs care. Multi-time and multi-technique information important – Kerry Hipps called contamination the “dirty secret of nanotechnology” – After one seminar I asked the speaker if the particles she was using for MALDI changed with time. Her comment was that “they certainly did, but no one seems to talk about it in the literature.” – How often do papers mention dynamic nature of nanoparticles?

Cleaning and Solvent effects on Nano-Structure

Measurements on Nanoporous Silica Film

Material Examined

• Porous organosilane glass, or p-OSG
• Film composition determined by RBS/HFS

– Si: 18% C: 18% O: 36% H: 28%

• 30-50% porosity (from literature) as deposited,

with 3 nm average pore size (up to ~10 nm)

• Deposited on Si wafer substrate

Nanoporous Silica films are being actively studies as a method to create low K dielectric materials for future high density integrated circuits.

S i dopin g layer

Specimens have been treated or processed in various ways including rinsing in Isopropyl Alcohol (IPA). The IPA rinse appears to change the thickness of the nanoporous films

Plasma processed p-OSG film before and after exposure to IPA

• “measured

thickness”;

– No IPA – 157 nm – IPA – 204 nm

400 nm plasma damaged

10 20 30 40 50 60 70 80 90 100 50 100 150 200 250 Depth (nm) At% C O Si C - IPA O - IPA Si - IPA

As received film After IPA Rinse

Erosion rate variations during XPS sputter depth profiling of nanoporous films Daniel J. Gaspar*, Mark H. Engelhard, Matthew C. Henry and Donald R. Baer Submitted to Surface and Interface Analysis

What does the FT-IR data tell us about changes in film chemistry?

• There are changes in C-H region

– Loss of alkanes or similar – Addition of IPA after rinse – even in vacuum

• FT-IR performed in vacuum bench
• IPA rinse does not change any Si- related modes
• IPA rinse does change C-H modes

The warning

Alcohol and other solvent cleaning procedures are quite common in preparing specimens for insertion into a vacuum chamber for surface

• analysis. For high surface area materials (nanostructured materials)

this may significantly alter surface composition and chemistry. After 72 hours in vacuum, the initial properties return.

Sputtering Effects

Real and Apparent Erosion rate variations during XPS sputter depth profiling

• f nanoporous films, D. J. Gaspar, M. H. Engelhard, M. C. Henry and D. R.

Baer,Surface and Interface Analysis 37,417 (2005). Straightening Suspended Single Walled Carbon Nanotubes by Ion Irradiation, Jung, Homma, Vajtai, Kobayaski, Ogino and Ajayan, Nano Letters 4 (2004) 1109 Shocks in Ion Sputtering Sharpen Steep Surface Features, H. Henry Chen, Omar A. Urquidez, Stefan Ichim, L. Humberto Rodriquez, Michael P. Brenner, Michael J. Aziz* Science 310, 294 (2005) Challenges in Applying Surface Analysis Methods to Nanoparticles and Nanostructured Materials, D.R. Baer, M. H. Engelhard, D. J. Gaspar, D. W. Matson, K. H. Pecher, J. R. Williams, and C.M. Wang, Journal of Surface Analysis 12 (2005) 101.

Damage Created by 5 kV Ar+ Collision cascade spreads through solid film, but must dissipate in much smaller volume for particle

Collision cascade nearly same size as particle

Are there physical reasons why nanoparticles Are there physical reasons why nanoparticles should sputter faster than films? should sputter faster than films?

d = particle diameter Rp = ion projected range 0 4 8 12 16 d/Rp Adapted TRIM calculation of small particle sputter rates For 5 kV argon this range is about 8 nm. Suggests effects for 30 nm particles.

Simulation of ion interactions with nanoparticles

Current work by Ram Devanathan at PNNL

Ram Devanathan, Fundamental Science Directorate ram.devanathan@pnl.gov 509-376-7107

Simulation of a nano grain of interstellar dust amorphized by cosmic rays

Sputtering of Nano Sputtering of Nano-

• structured Materials

structured Materials

There are good physical reasons to expect particles, nanoparticles and other nano-structured materials to behave significantly differently during sputtering than bulk or thin film versions of the materials. This can impact AES and XPS analysis and is of course essential to SIMS. High surface area will attract and hold impurities and contaminants that may impact chemistry and what happens during ion bombardment.

Collective Nature? Is there a mob character to nanoparticles?

• Anter El-Azab Florida State University statistical homogeneity
• , Magnetic Quantum Dots: Synthesis, Spectroscopy, and Magnetism of

Co2+- and Ni2+-Doped ZnO Nanocrystals, Dana A. Schwartz, Nick S. Norberg, Quyen P. Nguyen, Jason M. Parker, and Daniel R. Gamelin J. AM.

• CHEM. SOC. 2003, 125, 13205-13218 9 13205
• Structure-Property Relationships of a Nanocomposite Material –

Presentation Dr. Arthur J. Yang, ISTN INC, (Industrial Science Technology Network)

• Paul Davis Pacific Lutheran University Gold nanoparticles and aggregate

effects

• Ceria Nanoparticles - Sudipta Seal, Bera Debasia and Satyanarayana

Kuchibhatla University of Central Florida

• Enhancing coating functionality using nanoscience and nanotechnology

Donald R. Baer., Paul E. Burrows, Anter A. El-Azab Progress in Organic Coatings 47 (2003) 342–356

• The plasmon structure for nano-size objects differs from bulk material. See

series of papers by JL Gervasoni at co workers. See for example: Stopping force on point charges in cylindrical wires, AA Aligia, JL Gervasoni, and NR Arista,Phys. Rev. B 70 (2004) 235331

Isolated Nanoparticles Supported nanoparticles Aggregated or compacted nanoparticles

What properties of nanoparticles change as they are grouped or supported?

Compacted Powder

Direct Control of the Magnetic Interaction between Iron Direct Control of the Magnetic Interaction between Iron Oxide Nanoparticles through Oxide Nanoparticles through Dendrimer Dendrimer-

• Mediated Self

Mediated Self-

• Assembly

Assembly

Benjamin L. Frankamp, Andrew K. Boal, Mark T. Tuominen, and Vincent M. Rotello,

• J. AM. CHEM. SOC. 2005,

127, 9731-9735 9 9731 Interparticle spacing is a key factor in determining

• ptical, electronic, and

magnetic response in nanoparticle composites.

Relation between blocking temperature and particle spacing. The blocking temperature is the where a transition occurs between paramagnetic and ferromagnetic behavior Systematic increase in interparticle spacing as PAMAM generation increased

UV/VIS Absorbance Spectra of Au Nanoparticles: Effects of aggregation

Data from Prof. Paul Davis, Pacific Lutheran University Students Chris Bingham and Sean Tuley

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 400 500 600 700 800 900 1000 1100 1200 Wavelength [nm] Absorbance 3 min 40 min 60 min 90 min 2 days

Transverse Surface Plasmon Band Spherical Nanoparticles Extended Plasmon Band Changes with aggregation 3 min 40-90 min 2 days 2 days

• r Composite

Isolated Nanoparticles Supported nanoparticles Aggregated or compacted nanoparticles

Some properties of nanoparticles will change Some properties of nanoparticles will change as they are grouped, supported or integrated as they are grouped, supported or integrated into composites. into composites.

These effects are in addition to those caused by Size These effects are in addition to those caused by Size

Compacted Powder

Four Messages Four Messages

1. Adequate characterization frequently requires an integrated multi integrated multi-

• technique approach

technique approach 2. For fundamental reasons nano-structured materials are a challenge to characterize challenge to characterize.

.

3.

• 3. Routine sample handling, data collection, and

Routine sample handling, data collection, and analysis approaches may not be satisfactory analysis approaches may not be satisfactory – near state of the art data analysis, data modeling, and use of information from other methods can be important.

4. 4. Exciting opportunities Exciting opportunities – There are many new methods, major advances in older methods, and new approaches to data analysis.

February 28, 2006, Madison, WI--When University of Wisconsin (UW)-Madison graduate student Pengpeng Zhang successfully imaged a piece of silicon only 10 nm in thickness, she and her research colleagues were puzzled. According to established thinking, the feat should be impossible because her microscopy method required samples that conduct electricity. "What this tells us is that if you're building nanostructures, the surface is really important," said Evans.. But it turns out that silicon conducts much worse if the surface is poorly prepared and much better than that if the surface is well prepared." Knezevic's model indicates that in layers thinner than 100 nm, the properties of silicon itself become irrelevant: what matters is the surface.

Clean nanothickness silicon has conductivity boost

Importance of surfaces Importance of surfaces

Real Samples

Sensors Porous Pb-O-S battery electrode Iron Nanoparticles Catalyst Powders Carbon Nanotube Array Titania Nanorods Shape assumed by most XPS analysis Uniform layer that we “see” with XPS Nanosprings bacterium Bacillus subtilis

What is wrong with using the simple uniform analysis approach?

• Assumes that everything is uniformly

mixed over analysis volume.

• Composition usually given in atomic %

assuming that carbon is mixed with everything else.

• For many types of samples, there is a

surface contamination layer.

• Stating all elements with carbon included,

give false sense of sample composition.

• A carbon layer can distort peak ratios for

base elements if there are significant BE differences.

• Can calculate C layer thickness and

correct for effects of signal strengths

J.E. Castle, M.A. Baker, 105 (1999) 245. János Végh J. Electr. Spectrosc. Rel. Phenom. 133 (2003) 87–101

.

Impact of Layered Structures on XPS Signal Strength Well Known

From XPS MultiQuant Manual

Miklos Mohai , Hungarian Academy of Sciences Mohai@chemres.hu http://www.chemres.hu/aki/XMQpages/XMQscreens.htm

Layers-on-plane model Layer 1 Layer 2 Substrate I1 I2 Isubstrate

XPS MultiQuant

Miklos Mohai , Hungarian Academy of Sciences Mohai@chemres.hu http://www.chemres.hu/aki/XMQpages/XMQscreens.htm

Although most XPS analysis implicitly assumes that the surface i Although most XPS analysis implicitly assumes that the surface is a s a uniform flat homogeneous layer, other approaches are useful when uniform flat homogeneous layer, other approaches are useful when additional information is available. additional information is available. MultiQuant provides a useful approach, but is not designed to deal with nanoparticles. Effectively requires that “core” layers are thicker than the electron path length and that the particle size is smaller that the analysis area.

0.5 nm layer on substrate IMFP of ≈ 1.65 nm (TPP)

Flat Plate Ratio Observed Damage Fraction

Particle-aggregate size range

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 20 30 40 50 60 70 80 90 100 Diameter [nm] Fraction of Signal from Damage Layer

For larger sizes the shape effects are relatively insensitive to curvature As particles get smaller, the amount of signal from surface layer increases

Influence of particle size on curvature effect

Shape impacts of nanoparticles and nanostructured materials can be handled, but it is not yet routine.

• In many cases, information from other

techniques such as AFM, SEM or TEM is needed to improve XPS analysis

• Well known and defined systems are easier to

deal with.

Four Messages Four Messages

1. Adequate characterization frequently requires an integrated multi integrated multi-

• technique approach

technique approach 2. For fundamental reasons nano-structured materials are a challenge to characterize challenge to characterize.

.

3. 3. Routine sample handling, data collection, and analysis approache Routine sample handling, data collection, and analysis approaches s may not be satisfactory may not be satisfactory – near state of the art data analysis, data modeling, and use of information from other methods can be important.

4.

• 4. Exciting opportunities

Exciting opportunities – There are many new methods, major advances in older methods, and new approaches to data analysis. Take

Take advantage of resources available including User advantage of resources available including User Facilities (including National Labs) and ASTM and ISO Facilities (including National Labs) and ASTM and ISO Recommended Practice. Recommended Practice.

Observations/Opinions:

• Important and interesting characteristics of nano-structured

materials are often ignored leading to incomplete “definition” of some nanomaterials.

• Many researchers underestimate the challenges of obtaining useful

data about nano-structured materials. Careful sample handling and use of multiple methods is important.

• Many studies of nano-sized materials involve inadequate
• characterization. Contamination and uncharacterized coatings may

be the dirty secret of nanotechnology.

• Surface analysis (and other) methods are under-used in the study
• f nano-materials. Successful use may require more advanced

understanding that often applied, modeling of experimental results and combining information combined using multiple techniques.

Nano-materials present a variety of challenges for

• characterization. Take advantage of National User Facilities

and ASTM and ISO Guides. These challenges are an indication of great opportunities

The cutting edge is the proper place to be!!

From: Brian C. O'Regan Sent: Friday, October 08, 2004 4:53 AM To: Baer, Donald R Subject: A quote from you. Hello, I think we haven't met yet, at least not in more than passing. But, I ran into this quote from an abstract of yours:

"Since nanomaterial systems often contain a relatively large amount of surface or interface area, it is natural to characterize them using tools designed to analyze surfaces and interfaces. In our work we have found that nanoparticles and other nanostructured materials can present a variety of obstacles to useful analysis." I couldn't agree more!

I am trying to design a useful (and hopefully "routine" ) tool kit for characterizing nanoparticle surfaces. I want to do some reasonably high throughput screening of particles from various sources, I want a student to be able to measure 5 or 6 characteristics on 6 or 8 materials without running the risk of meaningless results because of techniques that are very tricky to use, or beam lines with limited time available,

• etc. I imagine including some techniques for characterizing surface impurities when in

vacuum, but also some hopefully for interfaces in solid materials (e.g. devices like the kind I work on, solid state dye sensitized photovoltaic cells.). If you have any advice about novel techniques to look into , please drop me a hint.

Energy Research Center Netherlands