Nanoparticle Size and Concentration Estimation by - CNR-ISM

Combined LAser
Nanotechnology
Nanoparticle Size and Concentration Estimation by Calibration Line Method
by Laser-Induced Breakdown Spectroscopy
Can Korala,*, Marcella Dell’Aglio b, Remah ElRashedy a, Rosalba Gaudiuso a,b, Alessandro De Giacomoa,b
aDepartment
of Chemistry, University of Bari “Aldo Moro”, Bari, 70126, Italy
bCNR-IMIP sec. Bari, Bari, 70126, Italy
*Can Koral, [email protected]
It was observed that Ag I emission intensity during LIBS of Ag NPs deposited
on Si is linearly correlated with concentrations and dimensions of colloids.
•
The LIBS signal of NPs appears to vary consistently with the change in
concentration of the NPs, and to be affected as well by the particle size when
the concentration of Ag atoms is kept constant.
Ag NPs of different size produced by laser ablation in liquid [1].
•
14000
12000
10nm AgNPs
0.02 mg/ml in aqueous buffer,
NanoComposix, Inc.
Intensity (a.u.)
20nm AgNPs
0.02 mg/ml in
buffer,
Sigma Aldrich Co.
10000
aqueous
14000
20nm AgNPs (0.020 g/ml)
20nm AgNPs (0.010 g/ml)
10nm AgNPs (0.020 g/ml)
10nm AgNPs (0.010 g/ml)
10000
8000
6000
4000
2000
0
328.0
10nm AgNPs (0.020 g/ml)
10nm AgNPs (0.016 g/ml)
10nm AgNPs (0.010 g/ml)
10nm AgNPs (0.004 g/ml)
12000
Intensity (a.u.)
• Having a fast technique for size and concentration characterization of NPs
solutions is of extreme importance for the orientation of NPs to industrial
and daily life products.
•
8000
6000
4000
2000
328.5
329.0
339.0
339.5
0
328.5
340.0
329.0
Wavelength (nm)
339.0
339.5
340.0
Wavelength (nm)
8nm AgNPs by Ablation
A series of solutions with
different
concentrations
were prepared by direct
dilution by deionised water
Particle size distributions
were characterized by UV-VIS
spectrometer and absorption
results were crosschecked
with
certified
AgNPs
dispersions
•
Highly reproducible calibration lines with a correlation factor
close to unity were attained by using the standard calibration
curve method [2].
•
It has been found that slope is strictly dependent on the size of
the NPs in the solution such that the average NPs size and their
concentration have been determined with a limit of detection of
few ppb.
20nm AgNPs
6000
5000
Intensity (a.u.)
4000
0.5µl drops of NPs colloids
were put on silicon wafer
substrate.
y=2534x-101
R=0.96
3000
2000
1000
The solution was then evaporated by a focused single laser shot
to form a homogeneous coating layer of NPs on a circular area of
3.5 mm in radius.
0
0.2
0.4
0.6
0.8
1.0
Relative Concentration
•
In this work a specifically designed Laser-Induced Breakdown Spectroscopy
(LIBS) setup was constructed to characterize the NPs size and the concentration
of the colloids.
The acquisition conditions were: Time Delay 800 ns, Gate Width 10 µs, Laser
Fluence 5 J/cm2, Spot Size 3.5mm.
10nm AgNPs
6000
5000
4000
Intensity (a.u.)
•
The LIBS Setup:
Q-switched Nd:YAG laser
(Quanta System, model:
Giant 770-10)
3000
2000
1000
0
Monochromator 250nm/750
nm
range,
1800
grooves/mm grating (Jobin
Yvon Horiba TRIAX 550)
0.2
0.4
0.6
0.8
1.0
Relative Concentration
8nm AgNPs
The laser pulse @ 1064nm was focused on to the
target by a lens of (f:100 mm), the emitted light was
reflected by an aluminum mirror(Ø:50 mm), the
reflected beam was collected through a biconvex UV
fused silica lens(f:75 mm) directly on to the
monochromator entrance slit.
The
target
was
rotated such that the
laser spot coincides
with the
rotation
axis and to ensure
the laser spot to
cover all the area
contaminated by the
NPs
6000
5000
y=5789-547
R=0.91
4000
Intensity (a.u.)
Intensified Charge Coupled
Device (ICCD) (Jobin Yvon
Horiba CCD-3000).
A
digital
delay/pulse
generator
(Stanford
Research Systems model:
DG535)
y=5311x-866
R=0.98
3000
2000
1000
AgNPs produced by Laser Ablation
0
• Each emission spectrum was acquired in multi shot mode by averaging the
acquired spectra taken from the rotating target.
0.2
0.4
0.6
Relative Concentration
References:
[1] A. De Giacomo , M. Dell'Aglio , A. Santagata , R. Gaudiuso , O. De Pascale , P. Wagener , G. C. Messina , G. Compagnini andS. Barcikowski Phys. Chem. Chem. Phys.,15, (2013),3083-3092
[2] R. Gaudiuso, M. Dell'Aglio, O. De Pascale, G.S. Senesi, A. De Giacomo, Sensors 10 (2010) 7434-7468.
Acknowledgements
This poster draws on work undertaken as part of the project CLaN (Combined Laser Nanotechnology) co-financed by the Operational Programme ERDF Basilicata 2007-2013.
0.8
1.0