Molecular Sistemas de Bandas Intensidad

8/18/2019 Molecular Sistemas de Bandas Intensidad

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Characterization of organic materials by LIBS for exploration of correlation

between molecular and elemental LIBS signals

Shikha Rai and Awadhesh Kumar Rai

Citation: AIP Advances , 042103 (2011); doi: 10.1063/1.3650860

View online: http://dx.doi.org/10.1063/1.3650860

View Table of Contents: http://aipadvances.aip.org/resource/1/AAIDBI/v1/i4

Published by the American Institute of Physics.

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AIP ADVANCES 1, 042103 (2011)

Characterization of organic materials by LIBS forexploration of correlation between molecular and elementalLIBS signals

Shikha Rai and Awadhesh Kumar Raia

Laser Spectroscopy Research Laboratory, Department of Physics, Allahabad University, Allahabad-211002, India

(Received 3 March 2011; accepted 7 September 2011; published online 3 October 2011)

The present study is performed for the preparation of a database by accumulating

LIBS spectra of 4-nitroaniline and 4-nitrotoluene in air and argon. Changes in the

behavior of the molecular bands of the C2 Swan system and CN violet system as well

as of atomic lines of C, H and N in the LIBS signal are appreciable in argon. In order

to explore the correlation between observed LIBS signal and molecular composition

of these materials, normalized intensities of the emission lines have been estimated

for each compound. It has been found that the relative rates of increase/decrease in

the normalized intensities for all sets are higher for 4-nitrotoluene in argon. The cause

of the higher rate for 4-nitrotoluene might be due to the possession of a distinctivefunctional group. The ultimate goal behind the whole study is to use this data-base as

input for the discrimination of energetic materials. Copyright 2011 Author(s). This

article is distributed under a Creative Commons Attribution 3.0 Unported License .

[doi:10.1063/1.3650860]

I. INTRODUCTION

Real-time remote detection of energetic materials is a challenging area world wide because

of the widespread use of these materials in munitions has increases the risk of homeland attack

using these energetic materials. Therefore, interest in overcoming the difficulties arising from the

detection of energetic materials/nitro-compounds has grown over the past decade. As a result, therehas been much interest in developing a technique that is able to identify a wide variety of molecular

and elemental features of these materials simultaneously. Energetic materials are pure substance

or mixtures that chemically react and liberate large amounts of heat rapidly. These materials are

combustible in nature so in order to diagnose such materials we need a robust method (i) that requires

no sample preparation so that the possibility of sample contamination may be avoided and (ii) that

must possess non-destructive behavior. These materials may be inorganic or organic1 in nature and

can be divided into two broad categories, viz., low-energy and high-energy energetic materials based

on the factors related to how readily a reaction is initiated and its intensity.

There are different methods available for analysis of major and trace elements present in

energetic materials, like X-ray fluorescence, inductively coupled plasma atomic emission/mass

spectrometry and atomic absorption spectrometry (AAS).2 These are used for the determination

of trace elements concentrations of energetic materials. But, the present scenario desires an ideal

technique that would perform the analysis of major as well as trace elements simultaneously withoutthe need of dissolving the sample in solution that makes determination time consuming. In view

of these points, laser-induced breakdown spectroscopy (LIBS) is an appropriate technique because

of its merits, such as no sample preparation; remote, rapid, multi-element micro-analysis of bulk

samples existing in any phase (solid, liquid, gas);3–12 its capability for minimally destructive, in situ,

aEmail: [email protected];[email protected], 91-8858773774, 0532-2460993

2158-3226/2011/1(4)/042103/11 C Author(s) 20111, 042103-1


http://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860mailto:%[email protected]:%[email protected]:%[email protected]:%[email protected]:%[email protected]:%[email protected]://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860http://dx.doi.org/10.1063/1.3650860


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042103-2 S. RAI and A. K. Rai AIP Advances 1, 042103 (2011)

real-time detection; and it offers the flexibility of point detection in comparison to other conventional

techniques. In view of these factors, laser-induced breakdown spectroscopy (LIBS), is an alluring

technique and is used widely for the detection of energetic materials. 1

In principle, LIBS is atomic emission spectroscopic technique.13 In this method, an intense

pulsed laser focused on the sample surface causes evaporation, atomization and ionization of the

material, resulting in ablation of a small amount of material and the subsequent formation of amicro-plasma above the sample surface. This plasma emits light with characteristic frequencies

from ionic, atomic and molecular species. Such emitted light is collecte by a collecting lens and

focused onto a fiber optic attached to a spectrometer. A PC connected to the spectrometer displays

the recorded spectra, and thus provides the instant qualitative and quantitative information about

elemental composition,14–18 which is the “fingerprint” of the sample.

In the present paper our key aim is associated with exploration of the correlation between the

molecular formulae of the compounds and molecular bands/atomic lines present in their LIBS spec-

tra. An attempt has been made to describe the correlation of molecular formula of nitro compounds,

such as 4-nitroaniline and 4-nitrotoluene, with the spectral lines present in the LIBS spectra. The

motivation behind the correlation is stoichiometric ablation, i.e., the intensity of atomic, ionic and

molecular species emitted fromthe plasma providesthe true representation of the species/constituents

present in the sample.

II. EXPERIMENTAL

Several LIBS spectra were recorded to optimize the experimental, parameters such as laser

energy, lens-to-sample distance, shot variation, and orientation of emission collection optics. LIBS

data presented in this study were acquired using a pulsed Nd: YAG laser (532 nm, 425 mJ/pulse, 4 ns

pulse width), which was focused onto the sample with a quartz plano-convex lens of focal length

150 mm. The emission from the plasma was collected with fiber bundles and spectrally resolved

with an Ocean Optics (model LIBS 2000+) four channel high-resolution miniature spectrometer

equipped with a charge coupled device (CCD) detector (200-980 nm, 0.1 nm FWHM resolution).

Nitro compounds, such as 4-nitroaniline (99% purity), and 4-nitrotoluene (99%), and copper

metal powder (99.5%) were purchased from the Central Drug House Ltd., New Delhi, India. In

order to perform the LIBS experiments, pellets were prepared from powdered samples of pure

nitro compounds using a hydraulic press machine (supplied by Midvale - Heppenstall Company,

Philadelphia, USA, model 341-20) by applying a pressure of approximately 2x108 Pa. LIBS spectra

of these pellets were recorded in open atmosphere using the experimental setup described by the

authors elsewhere.19 Each spectrum is an average of 10 laser shots. One of the major difficulties for

recording LIBS spectra of energetic materials/nitro compounds in open atmosphere is the possibility

of air interference. So in order to minimize the effect of the ambient atmosphere, we have recorded

LIBS spectra of the nitro compounds in an argon atmosphere by pulsing the argon gas across the

sample surface at angle of 45◦ with respect to the laser beam (its arrangement is shown in Fig. 1(a))

and effect of this purging on the LIBS signal in an air atmosphere is shown in Fig. 1(b).

III. RESULTS AND DISCUSSION

Several LIBS spectra of 4-nitroaniline and 4-nitrotoluene were recorded to optimize the exper-imental parameters, such as laser energy, lens-to-sample distance, shot variation, and orientation

of the collection optics. After careful experimentation, we achieved the best signal-to-background

(S/B) ratio at a laser energy of 18 mJ; a constant lens-to-sample distance (LTSD) was achieved using

a focusing lens of 15cm focal length. Each LIBS spectrum is the average of 10 laser shots.

A. LIBS spectra of nitro compounds in air

Initially LIBS spectra of 4-nitroaniline and 4-nitrotoluene were recorded in air in the spectral

range of 200 to 950 nm using the experimental conditions discussed above. In air, there is the

possibility of interference by atmospheric O2 and N2 with the spectral lines of O and N along



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(a)

(b)

660 680 700 720 740 760 7800

500

1000

1500

2000

660 680 700 720 740 760 7800

500

1000

1500

2000

Ar(I)

H(I)

O(I)

N(I)

Wavelength (nm)

Air

L I B S I n t e n s i t y ( C

o u n t s )

Argon

Sample

Stage

Sample

Plasma

plume

Fiber optic

cable

Firing nozzle

for argon flow

having dimension

1mm x 5mm

Laser

Focusing

lens

argon cylinder

Spectrograph

equipped with CCD

detector

PC

FIG. 1. (a): Experimental arrangement for recording LIBS spectra in an argon atmosphere. (b) Comparison of LIBS Spectra

of nitro compounds recorded in ambient air and argon atmospheres.



5/12


with the molecular bands such as the CN violet system from the sample. Such interaction of

ambient air with the LIBS signals may give false information about sample composition. Thus, to

reduce the effect of the air environment within the analytical plasma, we have also recorded LIBS

spectra in an argon atmosphere which otherwise complicates the goal of discrimination of nitro

compounds/energetic materials.

B. LIBS spectra of nitro compounds in the presence of argon

To flow the argon across the surface of the sample, we used a bronze nozzle with dimensions of

1mm x 5mm (Fig. 1(a)). The nozzle was fitted onto the tip of a firing gauge which was connected

by tubing to the gas cylinder containing argon gas. The tip of the nozzle was placed at a distance

of 5 cm from the surface of the samples and at an angle of 45 ◦ with respect to the laser beam (on

the opposite side to the emission collection optics), as shown in Fig. 1(a). The flow of argon gas

was measured (5 litre/sec) with Penning- Pirani gauge associated with the argon cylinder. In this

way by pulsing the argon gas across the surface of the sample, the air atmosphere has been largely

replaced by argon atmosphere. LIBS spectra of nitro compounds (4-nitrotoluene) in the presence of

argon atmosphere show the presence of the atomic spectral line of argon at 763.5 nm (Fig. 1(b))

which clearly shows the presence of the argon atmosphere. Portions of the LIBS spectra of both

nitro compounds from 200-500 nm are shown in Figs. 2(a) and 2(b). The presence of C2 and CN

bands in air & argon are clearly seen in the LIBS spectra of these compounds [Figs. 2(a) and 2(b)].

For distinct visualization of these bands, expanded spectra for the spectral ranges of 380-392 nm

and 456-480 nm are shown in Figs. 3(a) and 3(b). After careful analysis of the bands observed in the

LIBS spectra, we found that they are related (i) to the CN (B2+→ B2+) violet system at 385.09,

385.47, 386.19, 387.14, 388.34 nm and (ii) to the and C2 (d 3IIg → a 3IIu) Swan system at 467.8,

469.7, 471.5 and 473.7 nm (Figs. 3(a) and 3(b)). The existence of C2 and CN molecular bands in

the LIBS spectra of these materials is primarily due to recombination of native carbon-carbon and

carbon-nitrogen in the laser-induced plasma of the samples. 20

C. Comparison of LIBS spectra of nitro compounds recorded in air and argon

atmospheres

Considerable alteration in the intensities of the different spectral lines and the molecular bands

was observed by comparing the recorded LIBS spectra under different conditions (air and argon).

Overall the intensity of the CN band system for both the compounds is reduced whereas the intensity

of the C2 bands is enhanced when the LIBS spectra are recorded in an argon atmosphere instead

of an air atmosphere. In addition to this, the intensity of the overall background in the wavelength

range of the C2 bands is also enhanced. Reduction in the intensity of the CN band system is related

to the reduction of the nitrogen content coming from ambient air due to replacement of air by argon.

The cause of the overall signal enhancement (including C 2 Swan system) is due to the confinement

of the laser-induced plasma in the presence of argon. Due to the heavier density and lower thermal

conductivity of argon relative to air, the overall plasma is confined near the sample surface in argon

relative to air. The confined plasma increases the number of collisions that might be responsible for

more excitation of species in the laser-induced plasma and leads to the enhancement of the overall

LIBS signal in an argon atmosphere.

D. Intensity ratio of C2 to CN bands in air and argon

Correlation of alteration in the intensities of molecular bands system appearing in the LIBS

spectra of both nitro compounds is useful for discrimination of these compounds. Therefore, we

have evaluated the intensity ratio of the C2 (473.7 nm) band to the CN (388.3 nm) band for each

nitro compounds in both the media. We have chosen the C 2 band at 473.7 nm and the CN band at

388.3 nm for calculation of the intensity ratio because these bands are the most intense. 21 It is clear

from Figs. 3(a) and 3(b) that the LIBS signal of C2 increases in argon while for CN, it decreases;

therefore we have estimated the normalized intensity ratio of C 2 /CN that also increases in argon.



6/12


(a)

(b)

200 250 300 350 400 450 500

0

100

200

300

400

500

200 250 300 350 400 450 500

0

100

200

300

400

500

C2 band system

CN band system

C ( I I )

C ( I I I )

C ( I )

I n t e n s i t y ( C o u n t s )

LIBS Spectrum of 4-nitroaniline in air

Wavelength (nm)

LIBS spectum of 4-nitroaniline in argon

200 250 300 350 400 450 5000

100

200

300

400

500

200 250 300 350 400 450 5000

100

200

300

400

500

C2 band system

CN band system

C ( I I )

C ( I I I )

C ( I )


Wavelength (nm)

LIBS spectrum of 4-nitrotoluene in air

LIBS spectrum of 4-nitrotoluene in argon

FIG. 2. (a) LIBS spectra of 4-nitroaniline in air and argon atmospheres in the wavelength range 200-500 nm. (b): LIBS

spectra of 4-nitrotoluene in air and argon atmosphere in wavelength range 200-500 nm.



7/12


(a)

(b)

384 392 456 464 472 480

0

100

200

300

400

500

600

384 392 456 464 472 480

0

100

200

300

400

500

600

LIBS spectrum of 4-nitroaniline in air

Wavelength (nm)


CN violet band system

C2 Swan band system

LIBS Spectrum of 4-nitroaniline in argon

384 392 456 464 472 480

0

100

200

300

400

500

600

384 392 456 464 472 480

0

100

200

300

400

500

600


LIBS Spectrum of 4-nitrotoluene in argon

Wavelength (nm)

C2 Swan band system

CN violet band system

LIBS spectrum of 4-nitrotoluene in air

FIG. 3. (a): Expanded LIBS spectra of 4-nitroaniline in thewavelengthranges 380- 392nm and454-480 nm. (b): Expanded

LIBS Spectra of 4-nitrotoluene in the wavelength ranges 380 - 392 nm and 454- 480 nm.



8/12


9/12


(a)

(b)

4 NA 4 NT

0.00

0.05

0.10

0.15

0.20

0.25

4-nitrotoluene (4NT)

4-nitroaniline (4NA)

N o r

m a l i z e d I n t e n s i t y R a t i o o f C

2 t o C N

In Air

In Argon

4 NA 4 NT

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.54-nitrotoluene (4 NT)

4-nitroaniline (4 NA)

N o r m a l i z e d I n t e n s i t y o f C

2

In Air

In Argon

FIG. 4. (a): Bar diagram of the normalized intensity ratio of two molecular bands of C 2 /CN present in LIBS of nitro

compounds in air and argon atmospheres. (b): Bar diagram of the normalized intensity of C 2 Swan bands present in LIBS

spectra of nitro compounds in air and argon atmospheres.



10/12


(c)

(a) (b)

4 NA 4 NT

0

5

10

15

20

25

30

35

40

45

504-nitrotoluene (4 NT)


N o r m a l i z e I n t e n s i t y o f C

Air

Argon

4 NA 4 NT

0

5

10

15

20

25

30

35

40

45



N o r m a l i z e d I n t e n s i t y o f

H

In Air

In Argon

4 NA 4 NT

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9



N o r m a l i z e d I n t e n s i t y o f N

In Air

In Argon

FIG. 5. (a): Bar diagram of the normalized intensity of atomic line of C present in LIBS spectra of nitro compounds in air

and argon atmospheres. (b): Bar diagram of the ormalized intensity of atomic line of H present in LIBS spectra of nitro

compounds in air and argon atmospheres. (c): Bar diagram of the normalized intensity of atomic line of N present in LIBS

spectra of nitro compounds in air and argon atmospheres.

TABLE I. Rate of increase of the intensity ratio of molecular bands (C2 /CN) and normalized intensity of C2 Swan band

when the LIBS spectra of nitro compounds are recorded in the argon instead of in an air atmosphere.

Sample % Increment of C2 to CN % Increment of C2

4-nitroaniline 5.3 % 19.02%

(C6H6N2O2)

4-nitrotoluene 30.66% 21.92%

(C7H7NO2)



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4 NA 4 NT

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09



N o r m a l i s e d N / O

R a t i o

In Air

In Argon

FIG. 6. Bar diagram of Normalized intensity ratio of two atomic lines (N744.2nm /O777.1 nm) present in LIBS spectra of nitro

compounds in air and argon atmosphere.

TABLE II. Percentage rate of change of the normalized intensity of atomic spectral lines of C, H and N evaluated from

LIBS spectra recorded in different atmospheres (argon and air).

Sample Normal ized Intensity of C Normalized Intensit y of H Normalized Int ensity of N N/ O

4-nitroaniline 13.93% 12.2% 10.61% 10.67%

4-nitrotoluene 44.74% 13.0 %- 31.43% 24.34%

signal of the target sample. The weight of the pellets of each nitro compound before and after the

experiment was measured using electronic analytical balances (LWL Precision Instruments LB-

210S). These measurements were repeated for five times and finally the average value of the ablated

mass of the five replicate measurements was used for the study. Our measurements and calculations

show that 200µg of the target material was ablated per laser shot. This amount of ablated mass was

used to calculate the number of moles of 4-nitroaniline and 4-nitrotoluene which are similar. The

number of molecules of 4-nitroaniline and 4-nitrotoluene are approximately equal to 8.72 x 10 17

and 8.78 x 10

17

, respectively. We see that the number of moles of 4-nitrotoluene and 4-nitroanilineare similar; thus the differences in the rate of increase/ decrease in their respective LIBS signals

is due to the higher content of C and H and lower content of N in 4-nitrotoluene as compared to

4-nitroaniline. Thus the experimental observation of this section also supports our statement given

above that there is a correlation between molecular formula of the compound and its LIBS signal.

IV. CONCLUSION

The experimental results of the present paper clearly show that there is significant change in

intensity of atomic spectral lines and molecular bands of both nitro compounds when their LIBS

spectra are recorded in an argon atmosphere. Furthermore our results reveal that the rate of change



12/12


of the in LIBS signal is correlated with the molecular formula of nitro compounds. Thus, LIBS data

(normalized intensity and the intensity ratio of molecular bands and atomic lines) obtained from the

LIBS spectra of nitro compounds recorded under different laboratory conditions may be helpful in

the formation of an appropriate database for discrimination of nitro compounds/energetic materials.

ACKNOWLEDGMENT

Financial assistance from the Board of Research in Nuclear Sciences), Bhabha Atomic Research

Centre, Mumbai (no. 2009/37/30/BRNS/2063) is gratefully acknowledged. Ms. Shikha Rai is also

grateful to Council of Scientific and Industrial Research for providing Senior Research Fellowship.

1 F. C. DeLucia, R. S. Harmon, K. L. McNesby, R. J. Winkel and A. W. Miziolek, Appl Opt. 42, 6148 (2003).2 B. Fairman, M. W. Hinds, Simon M. Nelms, D. M. Pennyd and P. Goodalle, J. Anal. At. Spectrom. 13, 233R (1998).3 S. Pandhija, N. K. Rai, A. K. Rai and S. N. Thakur, Appl. Phys. B: Laser and Optics. 98, 231 (2010).4 V. K. Singh, V. Singh, A. K. Rai, S. N. Thakur, P. K. Rai, and J. P. Singh, Appl Opt. 47, (2008) G 38-47.5 D. A. Cremers and L. J. Radziemski, Handbook of laser- induced breakdown spectroscopy, John Wiley & Sons, Ltd,

(2006).6 J. L. Gottfried, F. C. De Lucia, C. A. Munson and A. W. Miziolek, Spectrochim. Acta B. 62 (2007), 1405-1411.7 J. L. Gottfried, F. C. De. Lucia, C. A. Munson and A. W. Miziolek, J. Anal. At. Spectrom. 23, 205 (2008).8 V. I. Babushok, F. C. DeLucia, P. J. Dagdigian, J. L. Gottfried, C. A.Munson, M.J. Nusca andA. W. Miziolek, Spectrochim.

Acta B 62B, 1321 (2007).9 J. D. Winefordner, I. B. Gornushkin, D. Pappas, O. I. Matveev, B. W. Smith, J. Anal. At. Spectrom. 15, 1161(2000).

10 F. C. De Lucia, A. C. Samuels, R. S. Harmon, R. A. Walters, K. L. Mcnesby, A. Lapointe, R. J. Winkel and A. W. Miziolek,

IEEE Sens. Jour. 5, 681 (2005).11 D. A. Rusak, B. C. Castle, B. W. Smith and J. D. Winefordner, Spectrochim. Acta Part B. 52, 1929 (1997).12 J. D. Winefordner, I. B. Gornushkin, T. Correll, E. Gibb, B. W. Smith and N. Omenetto, J. Anal. At. Spectrom. 19, 1061

(2004).13 A. Miziolek, V. Palleschi and I. Schechter, Laser Induced Breakdown Spectroscopy, Cambridge University Press, Cam-

bridge, UK, (2006).14 C. Pasquini, J. Cortez, L. M. C. Silva and F. B. Gonzaga, J. Braz. Chem. Soc. 18, 463 (2007).15 J. Anzano, M. E. Casanova, M. S. Bermudez, R. J. Lasheras, Polym. Test. 25, 623 (2006).16 M. A. Gondal and M. N. Siddiqui, J Environ Sci Health A 42, 1989 (2007).17 J. Anzano, R. J. Lasheras, B. Bonilla and J. Casas, Polym. Test., 27, 705 (2008).18 Q. Wang, P. Jander, C. F. Begemann and R. Noll, Spectrochim. Acta B. 63 (2008) 1011.19 S. Rai, A. K. Rai and S. N. Thakur, Appl. Phys. B: Laser and Optics, 91 645 (2008).20 H. L. XU, G. M´Ejean1, W. Liu1, Y. Kamali1, J. F. Daigle1, A. Azarm1, P. T. Simard, P. Mathieu, G. Roy, J. R. Simard

and S. L. Chin, Appl. Phys. B 87, 151 (2007).21 W. B. Pearse, and A. G. Gaydon, The identification of molecular spectra, 2nd edition Wiley, New York,(1976).22 NIST Atomic Spectra Database National Institute of Standards and Technology, Gaithersburg, MD, (2008).
http://dx.doi.org/10.1364/AO.42.006148http://dx.doi.org/10.1039/a809075khttp://dx.doi.org/10.1007/s00340-009-3763-xhttp://dx.doi.org/10.1016/j.sab.2007.10.039http://dx.doi.org/10.1039/b703891ghttp://dx.doi.org/10.1016/j.sab.2007.10.029http://dx.doi.org/10.1016/j.sab.2007.10.029http://dx.doi.org/10.1039/a910219lhttp://dx.doi.org/10.1109/JSEN.2005.848151http://dx.doi.org/10.1016/S0584-8547(97)00092-Xhttp://dx.doi.org/10.1039/b400355chttp://dx.doi.org/10.1590/S0103-50532007000300002http://dx.doi.org/10.1016/j.polymertesting.2006.04.005http://dx.doi.org/10.1080/10934520701628973http://dx.doi.org/10.1016/j.polymertesting.2008.05.012http://dx.doi.org/10.1016/j.polymertesting.2008.05.012http://dx.doi.org/10.1016/j.sab.2008.06.008http://dx.doi.org/10.1007/s00340-008-3040-4http://dx.doi.org/10.1007/s00340-008-3040-4http://dx.doi.org/10.1007/s00340-006-2536-zhttp://dx.doi.org/10.1007/s00340-006-2536-zhttp://dx.doi.org/10.1007/s00340-008-3040-4http://dx.doi.org/10.1016/j.sab.2008.06.008http://dx.doi.org/10.1016/j.polymertesting.2008.05.012http://dx.doi.org/10.1080/10934520701628973http://dx.doi.org/10.1016/j.polymertesting.2006.04.005http://dx.doi.org/10.1590/S0103-50532007000300002http://dx.doi.org/10.1039/b400355chttp://dx.doi.org/10.1016/S0584-8547(97)00092-Xhttp://dx.doi.org/10.1109/JSEN.2005.848151http://dx.doi.org/10.1039/a910219lhttp://dx.doi.org/10.1016/j.sab.2007.10.029http://dx.doi.org/10.1016/j.sab.2007.10.029http://dx.doi.org/10.1039/b703891ghttp://dx.doi.org/10.1016/j.sab.2007.10.039http://dx.doi.org/10.1007/s00340-009-3763-xhttp://dx.doi.org/10.1039/a809075khttp://dx.doi.org/10.1364/AO.42.006148

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