The “Where’s Waldo” Dilemma in Microscopy · • Scanning Electron Microscope (SEM)with Energy Dispersive X‐Ray Spectrometry (EDS, aka. EDX) • Electron Microprobe with Wavelength

The “Where’s Waldo” Dilemma in Microscopy

Wayne D. NiemeyerSenior Research Scientist

November 10, 2016

Search for the Known (Waldo) in a Complex Mix of Extraneous Stuff

There he is!

Mapping Instrumentation and Methods in Microscopy

• Fluorescence Microscope

• Scanning Electron Microscope (SEM)with Energy Dispersive X‐Ray Spectrometry (EDS, aka. EDX)

• Electron Microprobe with Wavelength Dispersive X‐Ray Spectrometry (WDS, aka. WDX) and EDS

• Secondary Ion Mass Spectrometry (SIMS)

• Raman Spectroscopy

• X‐Ray Photoelectron Spectrometry (XPS)            

[aka. Electron Spectroscopy for Chemical Analysis (ESCA)]

Olympus BH‐2 Fluorescence Microscope

Specialized Microscopy Fluorescence

• Commonly used in reflected light mode• Mercury vapor light source (100 watt)• Ultra‐violet and violet filters for monochromatic light• View visible wavelength light colors in eyepieces• Observe natural fluorescence in materials• Observe artificially induced fluorescent dyes (fluorochromes) in materials

Fluorescence MicroscopyAdhesion Promoter Dye/Resin Penetration into TPO

No Penetration

450 - 500 µm Penetration

100µm

100µm

Fluorescence MicroscopyBeverage Can/Aluminum End Seam

Can Sidewall

Aluminum End

Beverage

SealingCompound with Fluorescent Dye

JEOL JSM‐6480LV Scanning Electron Microscope (SEM)

Specimen Chamber

Monitors

Electron beam column

X-Ray Detector Specimen Chamber

Beam/Sample Interactions

JEOL

Image Formation

Movie presentation courtesy of:

OXFORD INSTRUMENTS

SEM/EDS Elemental MappingDry Dog Food Pellet

garnet

quartz

biotite orthoclase

anorthite

ilmenite

SEM/EDS Mineral Identification

JEOL JXA‐8200 Superprobe

Monitors

Electron beam column

EDS X-Ray Detector

Specimen Chamber

5 WDS X-Ray Spectrometers

NWA 176 Wavelength Dispersive X‐ray Maps

Magnesium Silicon

Oxygen

3.5”

2.5”

NWA 176 “Center” SEM Backscattered Electron Image

IronNickel

Sulfur

NWA 176 “Center” Wavelength Dispersive X‐ray Maps

Phosphorous

Smudge in Hair – Gunshot Residue (GSR) or Dirt?

We search for sub-10µm characteristic GSR particles which contain:lead (Pb), barium (Ba), antimony (Sb)

Hair Images by Transmitted Light Microscopy

50 µm

One Strand of the “Dirty” Hair Strands of Clean Hair

Smudge in Hair – Gunshot Residue (GSR) or Dirt?

BEI Image of Hair Tape Lift

WDS Maps – GSR!

Pb

Ba Sb

Cameca IMS 1280 Secondary Ion Mass Spectrometry (SIMS)

Ion Source and Specimen Chamber

Mass Analyzer

Detector

Primary Ion Beam

Secondary Ions,Atoms, ElectronsSecondary Ions,Atoms, Electrons

Secondary Ions, Atoms, Electrons

SIMS Sputtering Process

SIMS Technique 

Mass Analyzer

SampleSample

Primary Ion Beam( O2

+ , O–, Ar+, Cs+, Ga+ )

Coating Craters in Aluminum Cans

SIMS Ion MapsSEM Images Corrosion Pit

SIMS Ion Maps

Pit #1 Pit #2

Calcium

Boron

Iron

SIMS Ion Images of Beryllium‐Containing Particles

Renishaw inVia Raman Microscope

Raman mapping can be performed on:• Tablets (distribution of active ingredients)• Inks and pigments (document forgery, art 

conservation)• Electronics (silicon integrity)• Rocks (distribution of minerals)• And more!Spatial resolution from several mm down to ~ 1 µm

Raman Spectroscopy

inelastically scattered light (Raman)(different wavelength)

laser light(incident light)

scattered light (Rayleigh)

Raman spectroscopy measures inelastically scattered light; the difference in wavelength between the inelastic light and incident light corresponds to a vibrational mode

Information about molecular groups and crystalline structures

Raman map collected using 50X magnification, 785nm excitation laser

Example:  Calcium carbonate and sucrose distribution from a supplement tablet 

Calcium carbonate

Sucrose Overlay

LM Image

Physical Electronics Quantum 2000 Scanning ESCA Microprobe

Sample Chamber

XPS — InstrumentationSchematic of XPS Analysis using Focused, Monochromatic X-rays; a Hemispherical Electron Analyzer; and a Multichannel Detector

Electron Gun

Aluminum Anode

Ellipsoidal Monochromator

Sample

Electron Beam

Hemispherical Analyzer

Multichannel Detector

X-ray BeamPhotoelectrons

Hardware &Software

XPS Spectrum

Carbon Centroid Map and Basis Areas XPS LLS Fit Basis Spectra

XPS LLS Fit Maps LLS Fit Map Overlay

XPS — Chemical State Mapping

Summary• The “Where’s Waldo Dilemma” in microscopy can be solved

• Multiple instrumentation and methods can be employed to produce distribution maps of materials, i.e., if it’s there we’ll find it!

(OK, most of the time!)

• The choice of instrumentation/method is sample dependent and requires careful strategic planning with the client to provide the most useful results.

Thank you for joining us today.

Questions?

Wayne D. NiemeyerSenior Research Scientist

wniemeyer@mccrone.com (630) 887-7100