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Idaho National Engineering and Environmental Laboratory

The INEEL is a facility operated for the U.S. Department of Energy GA00 017

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LASER-INDUCED PLASMAA VERSATILE TOOL FOR CHEMICAL ANALYSIS

(over

aser-Induced Plasma, such asLaser Induced Breakdown

Spectroscopy (LIBS) and

Laser Induced Fluorescence

(LIF), makes real-time and

in-situ analysis possible.

LIBS Uses Laser toInduce Plasma

In principle, LIBS is

similar to ICP (InductivelyCoupled Plasma). The

difference is that instead of

using an electrode, LIBS useslaser to induce plasma. LIBS

has been an active research

topic since the 1960s, and isbeing moved to a variety of

field applications since the

introduction of dependablecompact pulsed lasers,

sensitive high speed detector

arrays, and low loss opticalfiber cables.

As shown in Figure 1, a

basic LIBS system consists ofa sufficiently power laser, a

fiber optic cable, a

spectrometer, and aphotodiode. The laser

commonly used is of

neodymium yttrium garnet

(Nd:YAG) type, which

produces up to 420millijoules of energy at 1.064microns in a 5-7 nanosecond

pulse with a repetition rate of20 Hz.

LIBS Has AdvantagesOver ICP

As given in Table 1, LIBSare superior to ICP in many

respects. Those unique

features make LIBS apromising technique for filed-

based and industrialapplications:

Real-time analysis for

process control

In-situ analysis ininaccessible locations and

hostile environments

Field sorting analysis suchas for geological samples

LIF (Laser InducedFluorescence)Enhances Sensitivity

One of the disadvantages of

LIBS is thesignificant matrix

effect, which lowers thesensitivity of LIBS. LIF,

Figure 1.Schematic

diagram of LIBS.

The plasma is

formed by

focusing optical

pulses from a

sufficiently power

laser.

Field Portable DeviceNo Sample Preparation

Small Sample Size (mili- to nano- gram)High Spatial Resolution

Works on Solids, Liquids, and Gases

Laboratory DeviceSample Dissolved and Nebulized

Relative Large Sample SizeRelative low Spatial Resolution

Works on Aqueous Aerosol

LIBS ICP

Table 1. Comparison of LIBS and ICP. The Crater produced by laser shot is only about 1 mm in diameterand about 70-80 micron in depth.

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however, can improve thedetectability by one order. In

LIF, a second pulsed-laserbeam is used to selectively

excite the metal atoms

causing them to emit a pulseof fluorescent light at a

characteristic wavelength.

INEEL (Idaho NationalEngineering andEnvironmentalLaboratory)

- A Leader in LIBSTechnology

The Plasma and Applied

Optics Department at INEEL

has extensive experience in

the development and

application of optical

instrumentation.

INEEL Is the Scene ofSome of the MostAdvanced ResearchPrograms in The World

INEEL, being operated byBechtel BWXT Idaho for theU. S. Department of Energy,

is the home of the largestconcentration of technical

professionals in the northern

Rocky Mountain region.Founded in 1949, INEEL has

made strong technical

contributions to regional andnational programs in the

areas of energy availability,

waste management, defensesystems, earth sciences, and

engineered systems. TheINEEL site covers nearly

570,000 acres and it currentlyhas about 9,000 employees,

among them more than 3,000

with engineering and sciencedegrees.

INEEL Has the LeadingEdge in OpticalInstrumentationDevelopment AndApplication

The INEEL Plasma and

Optics ApplicationDepartment is specialized in

the following fields:

High speed gratingspectroscopy

Pulse laser spectroscopy

Radiometry

Specialized imaging system

Here are two examples offield-based and miningrelated applications:

Real-Time Transuranic

Dust Monitoring (RTDM)

- An in-situ device uses

optically-based

measurements to rapidlyestablish size and density

of particles, andconcentrations of heavymetal species in the dust

generated in theremediation activities.

Preliminary Study of anOn-Line Copper Cathode

Analyzer- A project toassess the feasibility of

using LIBS for on-line

analyzing contaminants incopper cathode. Six

contaminants including Ni,

Pb, Ag, Sn, Fe and Te weredetected to low ppm levels

(see Figure 2 and Table 2).Although the sensitivitiesare not very satisfactory,

LIBS is certainly apromising technique in thisfield and several

modifications will be

probed for improvement.

Figure 2. ASpectral Scanof Lead. Thesamplecontained 114ppm Pb and thescan wasperformed with

a 2400 l/mmgrating.

Nickel

LeadTin

SilverIron

Tellurium

19.6

1.42.2

1.03.0

0.75

Contaminants

Detection Level

(ppm)

Table 2. DetectionLimits. All thedetection levels arein ppm exceptNickel.

(continued)

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INEEL is Willing toWork Together with Youfor Implementing theState-of-Art LIBSTechnique in YourSystem

INEEL will work closely

with you to develop theLIBS/LIF method and

instrument based on yourneeds. Different procedureswill be tailed to fit into

different situations of yours.

The following example is astep by step procedure for

developing a on-line LIBS to

measure lanthanide inoperation control:

1. Develop detailed systemoperating requirements

2. Prepare samples for

testing

3. Perform scope tests toselect the best analytical

wavelengths

4. Conduct interferencetesting

5. Optimize operational

parameters and produce acalibration curve for each

sample stream

6. Define the best methodand relative accuracy for

total lanthanidedetermination of each andall streams

7. Establish method forreading samples from

moving belt and movingslurries

8. Define instrument

configuration, cost,installation, and service

requirements

9. Prepare a summary report

For informationcontact:

Jerry L. May

e-mail: jlm@inel.govPhone: (208) 526-6674

John Alexander

e-mail: jala@inel.govPhone: (208) 526-0849

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