Laser Ablation 101:An Introduction to LA-ICP-MS

Lucas SmithDirector of Business Development - Americas

Content• What is laser ablation ICP-MS?• Laser ablation vs other analytical

techniques• Laser sources and selection• The importance of washout times• Fractionation effects• Application examples• Q&A

66Zn+ E14-17

What is Laser Ablation?• A laser ablates a solid sample

& delivers material directly to the ICPMS for elemental analysis

• Eliminates dissolution step and most sample prep

• Maintain spatial resolution

What is Laser Ablation & Why do we care?• Rapid, sensitive multi-element detection at sub-ppm

levels.

• Eliminates (most) labor-intensive sample preparation

• Can sample virtually any material (including liquids)

• Flexible method development

• High spatial resolution of microfeatures

• Sample mapping and depth profiling capabilities

• No contamination of reagents from digestion/dilutions steps

Laser Ablation vs

Other Techniques

Sample AnalysisMethod

SampleType

AnalyticalRequirements

SEM/Microprobetechniques

GDMS and OES

XRF

Spark Emission

Laser AblationBulk

Spatial

Depth

Conducting

Non-conducting

Size/shape

Full coverage

Detection lim

its

Turnaround

What is Laser Ablation ICP-MS?

References: Hu et al, J. Anal. At. Spectrom., 2008, 23 & Eggins et al, Applied Surface Science 127-129 (1998)

Laser Ablation System – Excimer Light Path

Typical Set-Up

Helium (or Argon) SweepArgon Make-Up

Sample

Trigger (Optional)

ICP-MS

LASER

He

HelEx II Sample Chamber

Articulated gas inlet/outlet arm

Sample holder

Internal volume (cup)

S. M. Eggins, L. P. J. Kinsley and J. M. G. Shelley, Appl. Surf. Sci., 1998, 129, 278–286.

• Evolution of Steve Eggins original ANU design

Typical Lasers used in Laser Ablation

Nd:YAG LASER1064 nm

ArF Excimer LASER193 nm

Nd:YAG LASER1064 nm

2ndHarmonic532 nm

4thHarmonic266 nm

Nd:YAG LASER1064 nm

2ndHarmonic532 nm

3rdHarmonic355 nm

5thHarmonic213 nm

Femtosecond lasers

Nan

osec

ond

puls

e w

idth

Fs p

ulse

wid

th

Wavelength & Coupling Efficiency

266

• Highly light transmitting materials (e.g. quartz) absorb little light under 300nm

• About 20% is absorbed at 266nm

• About 50% is absorbed at 213nm

• > 90% is absorbed at 193nm

High Low

Particle Size High

PS Distribution High

Difference in Mass High

Difference in Volatility High

Particle Size Low

PS Distribution Low

Difference in Mass Low

Difference in Volatility Low

FRACTIONATION:When the elemental composition of the material measured at the detector is not representative of the sample’s true composition

Ideal Sample to minimize fractionation:Homogenous, high-density aerosol cloud consisting of small, similarly sized particles.

Fractionation

Liquid Nebulization

Laser Ablation

Reference: D. B. Aeschliman, S. J. Bajic, D. P. Baldwin and R. S. Houk, High-speed digital photographic study of an inductively coupled plasma during laser ablation: comparison of dried solution aerosols from a microconcentric nebulizer and solid particles from laser ablation, J. Anal. At. Spectrom., 2003, 18, 1008–1014

Analytical Implications

Wavelength and FractionationLaser Type Heating Effects Coupling

Efficiency with Translucent

Samples

Typical Particle Size

Distribution

Overall Fractionation

Effects

1064 nm High Very Poor Broad Poor

266 nm Moderate Poor Moderate Moderate

213 nm Low-Moderate Good Narrow Good

193 nm Low Excellent Very narrow Very Good

Femto Very Low Wavelength dependent

Very narrow Excellent (in metallic samples)

What does laser ablation look like?

What Can Be Ablated?• Zircons & a variety of geological samples

• Ice Cores (climatology)

• Paper and ink ablation (forensics)

• Hair Samples (Pb, As & Sr measurement)

• Sunflower leaf

• Metals

• Bio-analysis

Teledyne Laser Portfolio

LSX-213 G2+

Analyte Pharos

Analyte Excite & High Energy Systems

Fusions CO2 & Diode Systems

Iridia – The Evolution of Laser Ablation• Purpose design for high speed imaging

• Dual Attenuation enables stable low energy for bio-imaging applications

• Dual software controlled polarizers for geo-imaging applications

• Cobalt sample chamber for ultimate performance & flexibility

• Earth Sciences • Minerals, toxic elements, zoning, U-Pb dating, coral,

environmental record• Forensics

• Glass, paint, plastic, metals, inks• Archeology

• Ceramics, shards, bone, teeth• Pharmaceutical

• Tablet powders and coatings• Metals

• Alloys, precious metals, QC and defects• General Industrial Materials

• Glass, quartz, silicon• Biological/Medical

• Tissue (frozen or dried), bone, teeth

Application Areas

Trace elemental analysis of stalagmite

Chew et al,J. Anal. At. Spectrom., 2017, 32, 262

Agilent 7900 ICP-MSTDY PMI Analyte Excite with HelExSpot size: 7umScan speed: 20um/sRep Rate: 45Hz

“With an acquisition time of less than 10 minutes per map (which can be decreased even further), there are few reasons to perform spot analyses on complex polyphase zircons other than when sensitivity is needed.”

Zircon Geochronology

Elemental Distribution in Garnet

• HelEx II & ARIS• Around 30ms transient peaks

• ICP-TOF-MS (TOFWERK)

Large (> 5 mm) garnet porphyroblast from medium-grade metamorphic rocks from the

South Carpathians (Romania)

48 min Acquisition Time150Hz Rep Rate

Dr C Stremtan (Teledyne), Dr M Rittner (TOFWERK)

Data interpretation: comparison to histology by overlaying a sequential HE-stained microtome slice

• Evaluation of links between cell-types and the nuclide, compound, or anti-body distribution made possible

Frank Vanhaecke, University of Ghent

3D Fly-Over of Concentration Image

T Van Acker, University of Ghent

Zn in Mouse Small Intestine

50µm

• Deparaffinized 5 µm sections of mouse small intestine villi

• Pixel size of this image is 1 x 1 µm• Total image size 350 x 300 µm, • Spot size 1 µm, • laser rep rate 150 Hz, • energy density 0.44 J cm-2• Pixel acquisition rate 50 pixels/sec

(limited by ICP-MS software)

• 35 minutes to acquire data

• Cobalt Cell & Quad ICP-MS• HDIP Software

Amazingly Large Images • Zircon Grain

• 3 um spot size @ 250 Hz

• 4.7 Million Pixel 3D Images

• 2 hours to acquire on ICP-MS

• Mass: U238

• 7 Minutes acquisition time per layer

• 100 layers acquired

• Single laser shot per pixel

• Z 150 nm material removed

• 1.5 x 1.7 mm

Zircon from the Ditrau alkaline massif (Eastern Carpathians, Romania)

Cobalt – Engineered by Science

Three-Dimensional Reconstruction of the Tissue-Specific Multi-elemental Distribution within Ceriodaphnia dubia via Multimodal Registration Using Laser Ablation ICP-Mass Spectrometry and X-ray Spectroscopic Techniques. Stijn J. M. Van Malderen et Al, DOI: 10.1021/acs.analchem.7b00111

Our laser webinar series continues!

Laser Ablation 102: The Evolution of LA-ICPMS through Collaborative Science

Damon Green – VP of Marketed Technology

Laser Ablation 201: Applications of Laser Ablation & Data Reduction Strategies

Dr. Ciprian Stremtan (and Muffin) – Product Specialist