LASER INDUCED BREAKDOWN SPECTROSCOPY

B.PAVANI PADMA PRIYA

PHARMACEUTICAL ANALYSIS AND QUALITY ASSURANCE

ROLL NO.-10VV1S2308

J.N.T.U COLLEGE OF ENGINEERING,VIZIANAGARAM.

contents

Introduction

Principle

Instrumentation: Design

Operation

Advantages

Limitations

Applications

Recent scientific and technological

developments

Research articles

References

LASER-INDUCED BREAKDOWN SPECTROSCOPY (LIBS)

INTRODUCTION:

Laser Ablation : Removing material from a sample surface by

irradiating it with a laser beam.

After nearly 30 years of study, laser ablation has become the

basis of a new chemical analysis technology.

Two approaches are: 1) LIBS,(part-per-million sensitivity)

2) LA-ICP-MS(parts-per-billion sensitivity).

Principle

LIBS: TYPE of AES which uses a highly energetic laser pulse as

the excitation source.

Laser is focused to form a plasma, which atomizes and excites

samples until it ionises and analysed by a spectrometer.

The obtained spectra consist of lines corresponding to the

elements evaporated from the sample surface.

INSTRUMENTATION: DESIGN

LIBS system consists of :

Laser :- Nd:YAG, and Eximer.

Spectrometer :- either a monochromator / a polychromator

Fiber optics

Detector:- PMT / CCD(respectively to the spectrometer used)

attached to a spectrograph analyzes the collected plasma

light and this is coupled to a PC which can rapidly process

and interpret the acquired data.

INSTRUMENTATION: OPERATION

Operate by focusing the laser onto a small area at the

surface of the specimen; generates a plasma plume with

temperatures in excess of 1,00,000 K.

•

Based on physical composition, laser induced plasma can

be divided into three regions

Region-I: (central or core region) the

temperature is maximum and species

are in ionised state.

Region-II: (mid region) apart from ionised

species, both neutral and certain number

of molecular species are present.

Region-III: (extended region) temperature

is comparatively lower and larger density

of molecular species present.

As the plasma plume expands, constituent atoms in the ionized

gas become excited.

Over just a few microseconds, the excited atoms began to relax,

resulting in characteristic spectral emissions by accompanying the

spectrometer and detector (delay generator) which accurately

gates the detector's response time.

ADVANTAGES

Versatile sampling of solids, gases or liquids.

Little or no sample preparation.

Very small amounts of sample material.

Analysis of extremely hard materials.

Local analysis in micro regions offers a spatial resolving power.

Possibility of simultaneous multi-elemental analysis.

Potential for direct detection in aerosols.

Simple and rapid analysis.

LIMITATIONS Increased cost and system complexity.

Difficulty in obtaining suitable standards (semi-quantitative).

Large interference effects ( in the case of LIBS in aerosols,

the potential interference of particle size).

Detection limits are generally not as good as established

solution techniques.

Poor precision.

Possibility of ocular damage by the high-energy laser pulses.

APPLICATIONS• LIBS at the Industries:

Pharmaceuticals**:-

-analysis of drug and lubricant in tablets

-analysis of saline solution

-drug mapping

-homogeneity of samples

Environment:-

-detection of contaminants

-industrial effluents

Metallurgy:- solid or molten alloys (Al, Cu, Zn, Mg, steel, Co, Ni,Cr)

- process fluids

- galvanized steel

- molten salts

- depth profiling

Other Organics:- paper

- polymer

- wood

Minerals:- detection of various elements (Au, Cu, Ni, Fe, C, Ca, Al,

Mg, Si,Ti) in ore and ore slurry.

Recent Scientific and Technological Developments

• Increase in sensitivity by 1 to 2 orders of magnitude using

double-pulse laser bursts or mixed-wavelength pulses.

• LIBS analysis of multilayer samples with high depth resolution

micro-mapping of heterogeneous samples.

• One-shot multielemental analysis using Échelle spectrograph

tunable laser.

• Hyphenated techniques with Raman and fluorescence

spectroscopy.

• Use of femtosecond laser for LIBS applications.

RESEARCH ARTICLES Quantitative analysis of gallstones using laser-induced breakdown

spectroscopy.

• VK Singh, V Singh, AK Rai, SN Thakur ;Applied Optics, Vol. 47, Issue 31,

pp. G38-G47 (2008), opticsinfobase.org.

Identification and discrimination of Pseudomonas aeruginosa

bacteria grown in blood and bile by laser-induced breakdown

spectroscopy.

SJ Rehse, J Diedrich; Received 23 May 2007; Accepted 23 July 2007,Science

direct.com.

Variational study of the constituents of cholesterol stones by laser-

induced breakdown spectroscopy.

VK Singh, V Rai - Lasers in Medical Science, 2009 – Springer.com.

CONCLUSION

After nearly many years of study, LIBS has become the basis of

a new chemical analysis technology.

Mars science laboratory mission are planning to take the LIBS

instrument to the mars in 2012.

REFERENCES

• www.appliedspectra.com/technology/LIBS.html

• www.springer.com

• www.ncbi.nlm.nih.gov

• www.appliedspectra.com

• www.rsc.org/publishing/journals

• www.oceanoptics.com/products/libs.asp

• en.wikipedia.org/wiki/Laserinducedbreakdownspectroscopy

• www.eproceedings.org

• www.photonics.cusat.edu/Research_Laser Induced

Plasma.html