LASER-INDUCED BREAKDOWN SPECTROSCOPY (LIBS)

Laser-induced breakdown spectroscopy (LIBS) is an emerging technique for determining elemental composition in real-time. With the ability to analyze and identify chemical and biological materials in solids, liquids, and gaseous forms with little or no sample preparation, it is more versatile than conventional methods and is ideal for on-site analysis.
   This is the first comprehensive reference book explaining the fundamentals of the LIBS phenomenon, its history, and its fascinating applications across 18 chapters written by recognized leaders in the field. Over 300 illustrations aid understanding.
   This book will be of significant interest to researchers in chemical and materials analysis within academia, government, military, and industry.

ANDRZEJ W. MIZIOLEK is a Senior Research Physicist at the US Army Research Laboratory. His work is currently concentrated on nanomaterials research and on the development of the LIBS sensor technology.

VINCENZO PALLESCHI is a researcher in the Institute for Chemical-Physical Processes at the Italian National Research Council and, in particular, the Applied Laser Spectroscopy Laboratory.

ISRAEL SCHECHTER is Professor of Chemistry in the Department of Chemistry at the Technion–Israel Institute of Technology. His main scientific interest is in new methods for fast analysis of particulate materials.

LASER-INDUCED BREAKDOWN
SPECTROSCOPY (LIBS)

Fundamentals and Applications

Edited by

ANDRZEJ W. MIZIOLEK
US Army Research Laboratory

VINCENZO PALLESCHI
Instituto per i Processi Chimico-Fisici, Italy

ISRAEL SCHECHTER
Technion–Israel Institute of Technology, Haifa, Israel

CAMBRIDGE UNIVERSITY PRESS
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Cambridge University Press
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Published in the United States of America by Cambridge University Press, New York

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© A. Miziolek, V. Palleschi and I. Schechter 2006

A. Miziolek’s contributions are a work of the United States Government and are not protected by copyright in the United States.

This publication is in copyright. Subject to statutory exception
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the written permission of Cambridge University Press.

First published 2006

Printed in the United Kingdom at the University Press, Cambridge

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ISBN-13 978-0-521-85274-6 hardback
ISBN-10 0-521-85274-9 hardback

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Contents

Contributors

S. Michael Angel
Department of Chemistry and Biochemistry,
The University of South Carolina,
Columbia, SC 29208,
USA

Demetrios Anglos
Institute of Electronic Structure and Laser,
Foundation for Research and Technology – Hellas,
PO Box 1527,
GR 71110, Heraklion, Crete,
Greece

S. Beaton
ADA Technologies, Inc.,
Littleton, CO,
USA

Simon Béchard
Pharma Laser Inc.,
75 Blvd. de Mortagne,
Boucherville, Québec,
Canada J4B 6Y4

Holger Bette
Lehrstuhl für Lasertechnik (LLT),
RWTH Aachen,
Steinbachstr. 15,
52074 Aachen,
Germany

Marie-Christine Boiron
Equipes Interactions entre Fluides et Minéraux,
UMR 7566 G2R - CREGU Géologie et Gestion des Ressources Minérales et Energétiques,
Université Henri Poincaré,
BP-239, 54506-Vandoeuvre-les Nancy Cedex,
France

Valery Bulatov
Department of Chemistry,
Technion–Israel Institute of Technology,
Haifa 32000,
Israel

N. H. Cheung
Department of Physics,
Hong Kong Baptist University,
Kowloon Tong, Hong Kong,
People’ Republic of China

M. Corsi
Instituto per i Processi Chemico-Fisici del CNR,
Area della Ricerca di Pisa,
Via G. Moruzzi 1,
56124 Pisa,
Italy

David A. Cremers
Chemistry Division,
Los Alamos National Laboratory,
Los Alamos, NM,
USA

G. Cristoforetti
Instituto per i Processi Chemico-Fisici del CNR,
Area della Ricerca di Pisa,
Via G. Moruzzi 1,
56124 Pisa,
Italy

F. C. DeLucia, Jr.
US Army Research Laboratory,
AMSRL-WM-BD,
Aberdeen Proving Ground,
MD 21005–5069,
USA

Vincent Detalle
Industrial Materials Institute,
National Research Council of Canada,
75 Blvd. de Mortagne,
Boucherville, Québec,
Canada J4B 6Y4

Jean Dubessy
Equipes Interactions entre Fluides et Minéraux,
UMR 7566 G2R - CREGU Géologie et Gestion des Ressources Minérales et Energétiques,
Université Henri Poincaré, BP-239,
54506-Vandoeuvre-les Nancy Cedex,
France

Philip Evans
Applied Photonics Ltd,
Unit 8 Carleton Business Park,
Carleton New Road, Skipton,
North Yorkshire BD23 2DE,
UK

Cécile Fabre
Equipes Interactions entre Fluides et Minéraux,
UMR 7566 G2R - CREGU Géologie et Gestion des Ressources Minérales et Energétiques,
Université Henri Poincaré, BP-239,
54506-Vandoeuvre-les Nancy Cedex,
France

Pascal Fichet
CEA Saclay,
DPC/SCPA/LALES,
91191 Gif Sur Yvette,
France

P. French
ADA Technologies, Inc.,
Littleton, CO,
USA

Scott R. Goode
Department of Chemistry and Biochemistry,
The University of South Carolina,
Columbia, SC 29208,
USA

I. Gornushkin
Department of Chemistry,
University of Florida,
Gainesville, FL 32611,
USA

David Hahn
Department of Mechanical and Aerospace Engineering,
University of Florida,
Gainesville, FL 32611–6300,
USA

R. Harmon
US Army Research Laboratory,
Army Research Office,
PO Box 12211,
Research Triangle Park, NC,
USA

Amy J. R. Hunter
Physical Sciences Inc.,
20 New England Business Center,
Andover, MA 01810,
USA

Jean-Luc Lacour
CEA Saclay,
DPC/SCPA/LALES,
91191 Gif Sur Yvette,
France

J. J. Laserna
Department of Analytical Chemistry,
University of Málaga,
Málaga,
Spain

K. L. McNesby
US Army Research Laboratory,
AMSRL-WM-BD,
Aberdeen Proving Ground,
MD 21005–5069,
USA

Patrick Mauchien
CEA Saclay,
DPC/SCPA/LALES,
91191 Gif Sur Yvette,
France

Denis Menut
CEA Saclay,
DPC/SCPA/LALES,
91191 Gif Sur Yvette,
France

John C. Miller
Life Sciences Division,
Oak Ridge National Laboratory,
PO Box 2008,
Oak Ridge, TN 37830–6125,
USA
Present address: Chemical Sciences,
Geosciences and Biosciences Division,
Basic Energy Sciences,
Office of Science SC–14 Germantown
Building, US Department of Energy,
1000 Independence Avenue,
SW Washington,
DC 20585–1290, USA

A. W. Miziolek
US Army Research Laboratory,
AMSRL-WM-BD,
Aberdeen Proving Ground,
MD 21005–5069,
USA

Yves Mouget
Pharma Laser Inc.,
75 Blvd. de Mortagne,
Boucherville, Québec,
Canada J4B 6Y4

Reinhard Noll
Fraunhofer-Institut für Lasertechnik (ILT),
Steinbachstr. 15,
52074 Aachen,
Germany

N. Omenetto
Department of Chemistry,
University of Florida,
Gainesville, FL 32611,
USA

V. Palleschi
Instituto per i Processi Chemico-Fisici del CNR,
Area della Ricerca di Pisa,
Via G. Moruzzi 1,
56124 Pisa,
Italy

Ulrich Panne
Laboratory for Applied Laser Spectroscopy,
Institute of Hydrochemistry,
Technical University Munich,
Marchioinistrasse 17,
D-81377 Munich,
Germany

Christian G. Parigger
The University of Tennessee Space Institute,
Center for Laser Applications,
411 B. H. Goethert Parkway,
Tullahoma, TN 37388,
USA

Bill Pearman
Department of Chemistry and Biochemistry,
The University of South Carolina,
Columbia, SC 29208,
USA

Jack Pender
Department of Chemistry and Biochemistry,
The University of South Carolina,
Columbia, SC 29208,
USA

B. Peterson
US Army Research Laboratory,
AMSRL-WM-BD,
Aberdeen Proving Ground,
MD 21005–5069,
USA

Lawrence G. Piper
Physical Sciences Inc.,
20 New England Business Center,
Andover, MA 01810,
USA

Leon J. Radziemski
Physics Department,
Washington State University,
Pullman, WA,
USA

V. N. Rai
Diagnostics Instruments and Analysis Laboratory (DIAL),
Mississippi State University,
205 Research Blvd.,
Starkville, MS 39759–7704,
USA

Annie Rivoallan
CEA Saclay,
DPC/SCPA/LALES,
91191 Gif Sur Yvette,
France

R. E. Russo
Lawrence Berkeley National Laboratory,
1 Cyclotron Road,
Berkeley, CA 94720,
USA

Mohamad Sabsabi
Industrial Materials Institute,
National Research Council of Canada,
75 Blvd. de Mortagne,
Boucherville, Québec,
Canada J4B 6YA

Ota Samek
Department of Physical Engineering,
Technical University of Brno,
Technicka 2, 61669 Brno,
Czech Republic

Jon Scaffidi
Department of Chemistry and Biochemistry,
The University of South Carolina,
Columbia, SC 29208,
USA

Israel Schechter
Department of Chemistry,
Technion–Israel Institute of Technology,
Haifa 32000,
Israel

J. P. Singh
Diagnostics Instruments and Analysis Laboratory (DIAL),
Mississippi State University,
205 Research Blvd.,
Starkville, MS 39759–7704,
USA

B. W. Smith
Department of Chemistry,
University of Florida,
Gainesville, FL 32611,
USA

Michael Stepputat
Fraunhofer-Institut für Lasertechnik (ILT),
Steinbachstr. 15,
52074 Aachen,
Germany

Volker Sturm
Fraunhofer-Institut für Lasertechnik (ILT),
Steinbachstr. 15,
52074 Aachen,
Germany

Helmut H. Telle
Department of Physics,
University of Wales Swansea,
Singleton Park,
Swansea SA2 8PP,
UK

Elisabetta Tognoni
Instituto per i Processi Chemico-Fisici del CNR,
Area della Ricerca di Pisa,
Via G. Moruzzi 1,
56124 Pisa,
Italy

J. M. Vadillo
Department of Analytical Chemistry,
University of Málaga,
Málaga,
Spain

Andrew Whitehouse
Applied Photonics Ltd,
Unit 8 Carleton Business Park,
Carleton New Road, Skipton,
North Yorkshire BD23 2DE,
UK

J. D. Winefordner
Department of Chemistry,
University of Florida,
Gainesville, FL 32611,
USA

James Young
Applied Photonics Ltd,
Unit 8 Carleton Business Park,
Carleton New Road, Skipton,
North Yorkshire BD23 2DE,
UK

F. Y. Yueh
Diagnostics Instruments and Analysis Laboratory (DIAL),
Mississippi State University,
205 Research Blvd.,
Starkville,
MS 39759–7704,
USA

Preface

Richard E. Russo and Andrzej W. Miziolek

LIBS (laser-induced breakdown spectroscopy) has been described as “a future super star” in a 2004 review article by Dr. James Winefordner, a world-renowned analytical spectroscopist.¹ LIBS is the only technology that can provide distinct spectral signatures characteristic of all chemical species in all environments. LIBS can be used to chemically characterize any sample: rocks, glasses, metals, sand, teeth, bones, weapons, powders, hazards, liquids, plants, biological material, polymers, etc. LIBS can be performed at atmospheric pressure, in a vacuum, at the depths of the ocean, or extraterrestrially. LIBS can respond in less than a second, indicating if a spilled white power is innocuous or hazardous, using a single laser shot. A unique attribute of LIBS is that samples do not need to fluoresce, or be Raman or infrared (IR) active. It is the simplicity of LIBS that allows this diversity of applications; simply strike any sample with a pulsed laser beam and measure a distinct optical spectrum. The laser beam initiates a tiny luminous plasma from ablated sample mass. The plasma spectrum is a signature of the chemical species in the sample; spectral data analysis provides the chemical species composition and relative abundance. Because a pulsed laser beam initiates the LIBS plasma, there is no physical contact with the sample; laboratory and open-path standoff applications are readily employed. Simply put, the LIBS phenomenon represents an efficient engine to convert the chemical information of the target material to light information that can be captured efficiently and analyzed thoroughly by modern spectroscopic instrumentation and data analysis/chemometrics software.

   LIBS has been aggressively investigated for environmental, industrial, geological, planetary, art, and medical applications since the early 1980s, although initial LIBS papers appeared with the discovery of the ruby laser in 1962.¹ A comprehensive source of literature describing LIBS research and applications can be found in Applied Optics,² which dedicated a special issue to this technology, as well as an extensive review in 2004.³ Although traditionally classified as an elemental analysis technology, the use of broadband high-resolution spectrometers has recently extended LIBS applications to molecular species identification. The ability to detect molecular and elemental signatures with a single laser pulse offers unprecedented performance for emerging medical, biological, environmental, and security applications.

   With the growth and evolution of LIBS phenomenon understanding and application areas there has been a corresponding increase in LIBS practitioners, both engineers and scientists, as well as a growth in LIBS commercial activities, in both instrument manufacturing and applications for hire. In fact, the world-wide LIBS community has established a tradition of international conferences on a two-year cycle that include LIBS 2000 (Tirrenia, Italy), LIBS 2002 (Orlando, USA), LIBS 2004 (Málaga, Spain), and LIBS 2006 (Montreal, Canada). The European LIBS community has also established the EMSLIBS (Euro-Mediterranean Symposium) series with EMSLIBS 2001 (Cairo, Egypt), EMSLIBS 2003 (Crete, Greece), and EMSLIBS 2005 (Aachen, Germany). In addition there have been a multitude of LIBS symposia associated with Optical Society of America, Pittcon, and FACSS meetings.

   This book describes the history, current research in understanding fundamental processes, research to improve measurement performance, and examples of numerous applications requiring parts per million (p.p.m.) and parts per billion (p.p.b.) detection levels. Several chapters describe research efforts dedicated to improving detection capabilities. Achieving sub-p.p.b. levels would allow LIBS to compete with vacuum-based mass spectrometric measurements, without requiring a vacuum. As described throughout this book, there is a tremendous international effort to advance the LIBS technology, by addressing multiple laser pulses, short duration laser pulses, and new instrumentation. One area to increase sensitivity would be to utilize ablated mass more efficiently; current LIBS analysis detects only a fraction of the mass ablated and excited to optical emission. Focused fundamental research on laser-induced plasmas will provide advanced knowledge for efficiently generating, exciting, and detecting mass. There is a large body of supporting literature on laser ablation for other applications (micromachining, materials fabrication, nanotechnology, thin-film deposition) that is germane to LIBS; the fundamental mechanisms are the same, but the optimum parameters for application are not. Optimum parameters need to be established for analyzing diverse samples, for example organic residues compared with inorganic refractory bulk samples. Understanding plasma physics can provide new approaches for increased sensitivity by using external (for example light, radio frequency, magnetic fields) means for producing longer-lived, hotter, and denser plasmas. There have been numerous efforts to study the influence of the laser beam properties (pulse duration, wavelength, energy, and number of pulses) on LIBS analytical performance. The laser beam can deliver energy from femtoseconds to microseconds in duration. On the other hand, the LIBS plasma duration is generally several microseconds, although research needs to establish laser–plasma–property time relationships.

   Most LIBS applications are based on using a laser with wavelength of 1064 nm. Wavelength contributes to plasma heating with nanosecond pulses, but research needs to establish if IR is best when using short pulsed (femtosecond and picosecond) lasers, and the role of Bremsstrahlung absorption. The use of double and triple pulses is being aggressively investigated for improving sensitivity and reducing ambient interferences. Currently, the UV–IR (ultraviolet–infrared) spectral region is interrogated for analysis, but other spectral regions, such as hyperspectral, may provide enhanced measurement capabilities. Just as the broadband spectrometer opened new vistas in LIBS applications, understanding measurement principles will advance performance specifications for existing and new LIBS applications.

   Implementation of LIBS in a suite of applications requires diverse yet similar instrumentation. For example, LIBS can be used with a simple lens to focus the laser beam within a few millimeters from the laser, with an optical fiber to carry the laser beam to a remote physical location, or by using a telescope for open-path standoff applications. Improved LIBS systems for long-distance standoff measurements will benefit from advanced optical configurations. Other spectroscopic technologies (Raman, fluorescence, absorbance, light scattering) perform in open-path configurations, although they do not possess the versatility of LIBS. However, it would be easy to integrate LIBS with Raman and laser-induced fluorescence for additional measurement capabilities. An integrated system could use light scattering to identify a suspect particle based on its morphology and then Q-switch the same laser for simultaneous LIBS – all in the same system. A concern for open-path standoff laser-based analysis is eye safety. Although the FDA in the USA has established limits for pulsed exposure, these limits are for unfocused laser beams; LIBS requires a focused laser beam. As research progresses to advance LIBS sensitivity using various laser wavelengths, low-level eye-safe operation will be viable.

   New applications of LIBS are expected in medical, biological, security, and nano-technology. With the international effort to fabricate nano-devices, -structures, and -particles, new technologies will be required to ensure that these systems abide by their design criteria. LIBS can fulfill this requirement, but will need to operate on smaller spatial scales and with enhanced sensitivity. The widespread utilization of LIBS for these applications will require development of comprehensive spectral databases and data manipulation algorithms. Spectral libraries can be established for voluminous chemical species and rapidly be evaluated to determine distinct signature for classes of species. Mass spectroscopy, Raman spectroscopy, fluorescence, IR, NMR (nuclear magnetic resonance), and almost all spectral analytical technologies benefit from the use of spectral libraries – as will LIBS.

   This book challenges you to benefit from the current expertise and to imagine new applications and ideas for advancing LIBS. The chapters present the current status of fundamental and applied LIBS studies, from a community excited by the numerous capabilities and possibilities. Chemical analysis is a critical component of world survivability – for understanding nature, contamination, health, climate, microelectronics, terrorism, advanced materials, and other things. We believe that LIBS will play a dominant role in every aspect of society for chemical analysis. With continued research and application, LIBS is becoming a future super star of analytical spectroscopy.