Dra. Magna Santos Dr. Luis Díaz Colaboraciones · dieléctrica (BD) de benceno y ablación (PLA)...

INSTITUTO DE ESTRUCTURA

DE LA MATERIA

Teléfono 915616800915616800 [email protected]@iem.cfmac.csic.es

GRUPO DE PROCESOS MULTIFOTÓNICOS

Dra. Magna SantosDr. Luis Díaz

Colaboraciones:Dr. Josef

Pola

(Academia de Ciencias de la Republica Checa).Dr. J. J. CamachoDr. J. M. Poyato

(Universidad Autónoma de Madrid)


DE LA MATERIA


C3

F6

C3

F6†

C3

F6††

C2

F4

+ CF2 CF2

scan

wavenumber

Disociación Multifotónica

Infrarroja.Irradiación Dicromática

time delay

νCF

=0

time delay


DE LA MATERIA


Lásercolorante

Láser de N2

Generador de retrasos

L(24)Célula

Osciloscopio

S. H

E

Filtros/monocromador

L(50)

PV

D

F-D DL(8)

Generador de retrasos

Photon

–

Drag/Pirómetro

Fotomultiplicador

Láser de CO2

MONTAJE EXPERIMENTAL

D. FLáser de CO2


DE LA MATERIA


LÍNEAS DE INVESTIGACIÓN

Fotodeposición de estructuras nanométricas

Ablación inducida por radiación láser IR

TÉCNICAS EXPERIMENTALES


DE LA MATERIA


TÉCNICAS EXPERIMENTALES

Caracterización de Productos Finales

• FTIR• GC-MS• Raman• TEM• SEM

Análisis en Tiempo Real

• Espectroscopía

de Absorción• Espectroscopía

de Emisión (UV, V, IR)

• Fluorescencia Inducida por Láser (LIF)


DE LA MATERIA


FLUORESCENCIA INDUCIDA POR LÁSER:

EXCITACIÓNC2

(d3Πg

)

C2

a3Πu5 1 0 5 1 1 5 1 2 5 1 3 5 1 4 5 1 5 5 1 6 5 1 7

0

1

2

3

4

5 1 2 . 5 n m ( 1 , 1 )

5 1 6 . 0 n m ( 0 , 0 )

Inte

nsid

ad L

IF (u

.a.)

L o n g i t u d d e o n d a ( n m )

Barridode la

excitación

Detección de la emisióna una longitud de onda fija


DE LA MATERIA


CF X2Π

CF A2Σ+

2 2 0 2 4 0 2 6 0 2 8 0 3 0 0

0

1

2

3

4

5

Inte

nsid

ad L

IF (u

.a.)

L o n g i t u d d e o n d a ( n m )

FLUORESCENCIA INDUCIDA POR LÁSER:

DISPERSIÓN

223.8 nm223.8 nm223.8 nm

Excitación alongitud de onda fija


DE LA MATERIA


Fotodeposiciónde estructuras nanométrica

Encapsulados metálicos(Sistemas: SCP + Fe(CO)5

)

Depósitos poliméricos basados en Silicio(Sistemas: CFC, SCP, CES, DSCB, DMSe...)

(Especies:C2

, CH, CF, CF2

, CF3

, SiSe, Se2

,

SiHCl,...)

Depósitos poliméricos basados en Silicio


DE LA MATERIA



DE LA MATERIA


Muestra

h

Láser de bombeo

Láser de prueba

Detección

Ablación inducida por radiación láser IR


DE LA MATERIA


2 2 2 1 . 2 2 2 2 1 . 3 2 2 2 1 . 5 2 2 2 1 . 7 2 2 2 1 . 8 2 2 2 2 . 0 2 2 2 2 . 1 2 2 2 2 . 3 2 2 2 2 . 4

( 3 , 0 )

S i OA 1 Π X 1 Σ +

LIF

Inte

nsity

(a.u

.)

W a v e l e n g t h ( Å )

Estudios Espectroscópicos

Dinámica de la Pluma de Ablación

0 . 0 5 . 0 x 1 0 - 6 1 . 0 x 1 0 - 5 1 . 5 x 1 0 - 5 2 . 0 x 1 0 - 5 2 . 5 x 1 0 - 50

1

2

3

4

LIF

Inte

nsity

(u.a

.)

T i m e ( s )

0 . 7 c m 1 . 5 c m 2 c m


DE LA MATERIA


Nanostructured

carbon formation in IR laser- induced dielectric breakdown in benzene

assisted

by Ni/Co ablation

M. Santos , L. Díaz

Instituto de Estructura de la Materia, C.S.I.C

J. J. Camacho,

J.M.L. Poyato

Dpto

Química-Física Aplicada. UAMadrid

J. Pola, M. Urbanová

, D. Pokorná, Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, A.S.C.R.

J. Šubrt, S. Bakardjieva

Institute of Inorganic Chemistry, A.S.C.R.

Z. Bastle J.Heyrovský Institute of Physical Chemistry, A.S.C.R


DE LA MATERIA


1 Pyrex vessel, 2 valve to vacuum, 3 NaCl

window, 4 laser pulse, 5 lens,6 metal

sheet, 7 glass substrate, 8 ablation plume.

XPS

analysis, ESCA 310 (Scienta) electron spectrometer. SEM-

EDAX, Philips XL30 CP scanning electron microscope.TEM, JEOL JEM 3010 microscope (LaB6 cathode) operating at 300 kV.Optical Emission Spectroscopy, 1/8 Oriel

Spectrometer + Andor

DU420-OE CCD camera (1024x256 pixel matrix); resolution of ~1.3 Å

in first-order.

OBJETIVODeposición (LCVD) de nanodepósitos

de C mediante ruptura dieléctrica (BD) de benceno y ablación (PLA) simultánea de Ni o Co

con láseres

de CO2

.IR pulsed laser-induced decomposition of hydrocarbons yields graphene

layer-containing carbon nanoparticles

with properties more affected by the nature of hydrocarbon than by laser power. They differ from LCVD processes in which gaseous hydrocarbons are decomposed on substrates heated by IR lasers

TEA CO2 laser

(Lumonics

K-103), 10P(26) line at 938.71 cm-1, energies of 1 and 4 JFTIR

spectrophotometer, Perkin-Elmer 1600 and Nicolet

Impact.Raman spectroscopy, Renishaw

Ramascope

model 1000 Raman microscope, CCD detector, exciting wavelength 514.5 nm, 103 W/cm2.


DE LA MATERIA


Dielectric Breakdown

of 100 mb

(5 mb

with Co/Ni targets) gaseous benzene leads to:

Visible luminescence

due to emission of electronic species.Depletion of benzene, less efficient with Co sheet (♦) than with Ni target

(▲) or in pure benzene (□).Formation of gaseous hydrocarbons

(acetylene, diacetylene), typical products of benzene pyrolysis

and carbonization. The decreasing of acetylene to diacetylene

ratio in the presence of the metal target indicates that metal ablation induces some reactions in the plume. Deposition of black films

covering most of the reactor surface.


DE LA MATERIA


C, C+, C2+, molecular H2

and C2 are detected in BD of benzene or BD+ PLA of benzene + metal targets.

Ni, Ni+, Co, Co+

and Co2+

detected in BD+ PLA.

Emission Intensity from molecular C2

is increased with Ni or Co target, low fluences and low pressure

2000 3000 4000 5000 6000 7000

Δv=2

Δv=1

C2+

C+

C+ C+

NiNi

Ni

Ni+

Ni

C+

H2

C

CC2+C

Δv=-2Δv=-1

Δv=0

C2: d3Πg-a3

Πu

Rel

ativ

e In

tens

ity /

a. u

.

Air Wavelength / Å

a

b

c

2000 3000 4000 5000 6000 7000

Δv=2

Δv=1

C+

C+

C2+

C+

C+

C+

Co+

C2+

H2

Δv=-2

C

CoC

oCo

Co2+

Co+

Co2+

C

Rel

ativ

e In

tens

ity /

a. u

.

Air Wavelength / Å

Co+

a

b

c

C2: d3Πg-a3

Πu

Δv=0

Δv=-1

Optical

Emission

Spectroscopy


DE LA MATERIA


A

is a constant, λv’-v”

is the wavelength corresponding to the band head, qν‘-ν"

is the Franck-Condon factor and G(ν‘) h c/kB

is the normalized energy of the upper vibrational level v’.

A linear fit of this expression has a slope equal to -1/Tvib.

5000 5200 5400 5600 5800 6000 62000.0

0.2

0.4

0.6

0.8

1.0

C2+

C

CC

C

C4+

4-6

3-5

2-4

1-3

0-2C+

C2+

Δv=-2 C2: d

3Πg-a3Πu

C3+

C+

C+

4-5 3-

4 2-3 1-

20-

1

Δv=-1 C2: d

3Πg-a3Πu

2-2

1-1

0-0

Δv=0 C2: d

3Πg-a3Πu

Hβ

Air Wavelength / Å

Rel

ativ

e In

tens

ity /

a. u

.

The emission intensities of the C2 d-a Swan Δv=-1

band sequence were used

to estimate the vibrational

temperatures, Tvib

. For a plasma in LTE,

the intensity of an

individual vibrational

v’-v”

band Iv’-v”

is given

Vibrational

Temperature

vibBvv

vvvv

TkchvGAq

I⋅

−=⎟⎟⎠⎞

⎜⎜⎝⎛ ⋅

−

−− )'(ln"'

4"'"' λ

,


DE LA MATERIA


40000 42000 44000 46000 48000 50000 52000 54000-18

-17

-16

-15

-14

-13

-12

-11

-10

-9

ln(I k

i λki

/gk

Aki

) (a.

u.)

Ek/kB (K-1)

Co I T = 5000K

42000 43000 44000 45000-18

-16

-14

-12

-10

-8

ln(I k

i λki

/gk

Aki

) (a.

u.)

Ek/kB (K-1)

NiI T=5500K

70000 75000 80000 85000 90000 95000 100000 105000

-17

-16

-15

-14

-13

-12

-11

Ni II T = 22000 KY A

ln(I k

i λki

/gk

Aki

) (a.

u.)

Ek/kB (K-1)

excB

k

kik

kiki

TkE

CAg

I⋅

−=⎥⎦

⎤⎢⎣

⎡⋅⋅ λ

ln

,

T

is the temperatureIki

is the emissivity

in W·m-3·sr-1

of the emitted k→i

spectral line λki

is the wavelengthgk

=2Jk

+1 is the statistical weight

Aki

is the Einstein transition probability of spontaneous emissionEk

/kB

is the normalized energy of the upper electronic levelC=f(Q(T)) (Q(T) is the partition function)


DE LA MATERIA


Metal Sheet

Benzene

Pressure

(Torr)

C2 Vibrational

Temperature (K)

Excitation Temperature (K)

Ni+ Ni Co

Ni 5 5928 ±

300

Ni 1 5723 ±

300 22000 ±

70005500 ±

1500

Co 5 6274 ±

300

Co 1 6759 ±

300 5000 ±

1000- 100 6232 ±

300

Ionized species are produced, on the average, near the surface target in inner region of the ablation plume with higher temperature.

The atomic and molecular species come, on the average, from the low temperature region close to the plasma front, where the ionized atom density is lower.


DE LA MATERIA


Carbon deposited on the glass surface (a) show fluffy structure of amorphous ca. 40-60 mm-sized agglomerates.

Carbon deposited on the metal tagets resemble more compact bodies whose diffraction patterns show very weak diffuse rings and whose HRTEM images reveal disordered carbon previously characterized as fullerene or highly aromatic.

The SEM-EDX analysis of the carbon films deposited on glass or metal: oxygen is only of 1-3 atomic per cent of carbon irrespective of the substrate.

Properties of the filmsSEM TEM


DE LA MATERIA


Properties of the films

The FTIR spectra of the carbon

deposited on the metal sheets (a) show: ν(C(sp3)-H) band at 2870-2970 cm-1

a very distinct ν(C=C) band at 1630 cm-1 (blended with a contribution at 1710 cm-1

possibly reflecting ν(C=O) vibrations) and a broad ν(O-H) band at 3200-3600 cm-1

. Indicating that is more reactive in air .

Reflection FTIR spectra carbon deposited on (a) Ni target and (b) glass.

The FTIR spectra of the carbon

deposited on glass (b) show

only the ν(C(sp3)-H) band along with some minor bands at lower wavenumbers.


DE LA MATERIA


Exp. Target Film onG-band, cm-1

position / widthD band, cm-1

position / width ID /IG

1 None glass 1599 / 64 1355 / 201 1.29

2 Ni glass 1597 / 62 1357 / 183 1.02

2 Ni Ni 1591 / 65 1351 / 110 0.86

3 Co glass 1600 ./ 57 1358 / 226 1.05

3 Co Co 1590 / 67 1352 / 100 0.91

pure benzene

Metal substratGlass substrat Co ablation

Ni ablation

Ni ablation

Raman spectra of carbon deposited on both metal and glass show G

(1590-1600 cm-1) and D (1350-1360 cm-1) bands. The position and the width of the G band resemble those of graphitic a-C:H films and soot.

Carbon deposited on metal sheet have:

•G and D bands shifted towards lower wavenumbers.•

Lower ID /IG values (lower fraction of ring structures)•Sharper D band.

The Raman spectra thus indicate that the carbon deposited on the metals are more ordered than those deposited on glass.

Properties of the films

G band

D band


DE LA MATERIA


Conclusions

A TEA CO2

laser-induced dielectric breakdown in gaseous benzene in the presence and absence of metal (Ni, Co) sheets allows chemical vapour

deposition of nanostructured

carbon.

From OES experiments we obtain that in the ablation plume of Ni or Co sheets in the presence of benzene, neutral and ionic C along with molecular H and Swan C2

bands together with neutral and ionic Ni or Co are detected.

The obtained results show similar values of vibrational

and excitation temperatures for C2 and neutral Ni and Co atoms.

A much higher excitation temperature is obtained for the ionized Ni.

Theses results suggest that the ionized species are produced, on the average, near the surface target in inner region of the ablation plume with higher temperature. However, the atomic and molecular species

come, on the average, from the low temperature region close to the plasma front, where the ionized atom density is lower.

Low pressures favour the C agglomeration and Co metal sheets slightly enhance the vibrational

temperature of the formed molecular C2

species.

The different spectra of carbon remained on the metal sheet compared to carbon on glass reveal that carbon formation on the metals is assisted by the metal surface

The carbon deposited on the metal sheet differs from that deposited on glass in having more C=C and O-H bonds and possibly more fullerene moieties.

Dra. Magna Santos Dr. Luis Díaz Colaboraciones · dieléctrica (BD) de benceno y ablación (PLA)...

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Transcript of Dra. Magna Santos Dr. Luis Díaz Colaboraciones · dieléctrica (BD) de benceno y ablación (PLA)...