Unknown Material Analysis in Less Than A Second Man Portable LIBS A Tool for First Responders in Homeland Defense Roy A. Walters, Ph.D. PE Vice President,

Unknown Material Analysis in Less Than A Second

Man Portable LIBS A Tool for First Responders in Homeland Defense

Roy A. Walters, Ph.D. PE

Vice President, Research and Development

Ocean Optics, Inc.

Winter Park, Florida

[email protected]

What is LIBS?

Nd-Yag Laser

LIBS3000

Spectrometer

Computer -

Standard PC

Analyze

One 7 ns laser pulse

15,000 K plasma, much hotter than the sun’s surface but for only 20 microseconds

Identify < 0.5 sec

0.000000007 seconds

Who is a First Responder?

• Fire Department, Police, Public Health

• Specifically - an organization of specially trained people serving a single city or a region

• Includes– Haz-Mat team

– Swat team

– Medical emergency team

– etc.

What does the First Responder want an instrument to do?

• Find out what “it” is and not have to touch it or get very close

• If “it” isn’t pure material, find out what other things might be in it

Where and how does it have to work?

• Rain, snow, night, bright sunlight, hot days

• Portable with hours of time between battery charges

• Must be light and easy to carry

• Must be reliable

• Must give immediate answers

What do we need to identify?Not so nasty stuff

• Sodium hydroxide• Sodium carbonate• Adipic Acid• Aluminum Sulfate hydrate• Ammonium Nitrate• Urea• Terephthalic Acid• 1,2-propanediol (aka propylene glycol)• viscous and non-flammable Acetic acid• carbon black• potassium carbonate (pot ash)• Titanium dioxide• Arsenic• oxidebarium carbonate (for barium metal)• Cadmium• chromium• Lead• Mercury• Nickel• Zinc• sodium fluoride• Etc.                            

• There are 70 or so of these

Bad Materials

• Explosives or their residues and IEDs– Stable (RDX, TNT, C4, etc) LIBS does not explode them

– Unstable (London event)

– Explosive or corrosive gasses

• Biological materials (bacillus spores)

• Poisons

• Drugs

MP-LIBS A full laboratory High-Resolution Broadband LIBS system in a portable backpack

Head’s-up display

Hand-held probe contains laser, joystick for control, and focus optics

Microplasma/ LIBS Event

Backpack contains broadband high-resolution spectrometer, laser power supply, computer, and battery

MP-LIBS

• First responder in Full Class A protection Suit

• MP-LIBS should be inside suit

MP-LIBS Outside Backpack

Argon Bottle

for

Special targets

LIBS3000-gh spectrometer

Computer with cell phone and wireless network

How do we identify complex substances?

LIBS Spectrum

We have stored the 2-dimensional barcode of items of interest!

Position

Amplitude

ultraviolet Blue Green Red Infrared

Position

Amplitude

Mathematics

• Correlation– Checks everything in the catalog, tells you what

is closest and grades it, 1.0 being perfect, 0.0 being no correlation

– 2 types• Linear – all peak heights count according to how

high they are• Rank – Big peaks count more than little ones

What else do we do?

• PCA - a type of analysis

• PPA - Primary peak analysis– What’s missing from the closest matches, or

what is additional

• PPC - Peak picking correlation– Get rid of the junk between the big peaks

Then What?

• It’s time to vote to determine the winner• An example, pick the 10 highest scorers and for each calculate

• Score = 0.2 x (Rank Correlation) + 0.3 x (Linear Correlation) +

0.2 x PCA + 0.1 x PPA + 0.2 x (Peak Pick Correlation)

Then display the top 5 matching items and their scores

BGBTSugarSaltCreamer

1.000.590.490.470.46

What else are we doing?30 + meter long distance LIBS