Silica mesospheres were deposited on a silicon substrate to form a surface mask. Inorganic nanoparticles were deposited onto the mask and arranged during drying to form ring patterns. The mask was then removed, leaving behind only the nanoparticle rings. Atomic force microscopy was used to image the ring patterns of various inorganic nanoparticles, such as iron oxide, on the surface at high resolution. This particle lithography technique allows for the fabrication of well-defined circular arrangements of nanoparticles that could be useful for applications requiring ordered inorganic nanostructures.

1. Surface patterns of inorganic nanoparticles characterized with atomic force microscopy
Denzel Alexander, Xianglin Zhai and Jayne C. Garno*
Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803
Introduction
Acknowledgements
The authors gratefully acknowledge the support from the LSU Initiative for
Maximizing Student Development (IMSD) Program.
Louisiana Board of Regents Support Fund (LEQSF(2014-16)-ENH-TR-03)
Concentric rings formed with diverse nanoparticlesRings fabricated with FeCo nanoparticles
Atomic Force Microscopy (AFM)
Surface mask formed by self-assembly of mesospheres
Ring arrangements of nanoparticles were prepared using
particle lithography for nanofabrication. A suspension of
monodisperse silica mesospheres was deposited on a Si(111)
substrate and dried to form a surface mask. The crystalline
arrangement of the surface mask provided a template to guide the
deposition of inorganic nanoparticles. The surface mask was
removed using tape without rinsing or sonication. The nanoparticles
persist on the surface to form ring patterns. The sample was
characterized using tapping-mode atomic force microscopy (AFM).
.
Topography
Silica mesospheres were
deposited on a flat surface of
silicon to form a mask to
guide the self-assembly of
nanoparticles.
Nanopatterns defined by
micron-sized regions were
formed.
Using AFM, surfaces of ring
nanopatterns on silicon substrates
were imaged.
For tapping-mode AFM, a
tip-attached cantilever is driven to
vibrate vertically while scanning
across the sample to provide surface
topography and phase images.
A diode laser is deflected from the
cantilever to a quadrant photodiode
detector. Changes in tip position are
converted into digital images.
Circular patterns prepared with Fe3
O4
nanoparticles
Conclusions
150
nm
0
1 µm
200
nm
0
10
µm
500 nm
500 nm
150
nm
0
1 µm
10
µm
Deposition of mesopheres and
nanoparticles mixture
Arrangement of particles
during drying process Lift-off mesospheres
Phase
100
nm
0
1 µm
120
nm
0
2 µm
200
nm
60
nm
0
1 µm2 µm
200
nm
Deposit silica
mesospheres
Deposition of
nanoparticles onto
a surface mask
Arrangement of particles
during drying process
Lift-off
mesospheres
PhaseTopography
1 1
30
nm
0
1 µm
30
nm
0
3 µm
3 µm
25
nm
0
250
nm
250
nm
1 µm
TopographyPhase
Deposit silica
mesospheres
Deposit nanoparticles onto
surface mask
Deposit second
nanoparticle
Arrangement of two kinds
of nanoparticles
during drying process
Lift-off mesospheres
Ring arrangements of nanoparticles were fabricated with metal
nanoparticles using approaches of particle lithography.
Bowl shape arrangements of FeCo and Fe3
O4
metal nanoparticles
were formed in ring patterns.
Two types of nanoparticles were patterned in a concentric fashion
by sequential deposition.
Concentric ring structures with FeCo nanoparticles inside and
Fe3
O4
nanoparticle outside can be fabricated with two steps of
particle lithography. The multicomponent nanostructures have
the potential to carry out multiple functions synergistically.
Disc arrays FeCo nanoparticles were fabricated with “two-particle”
lithography. This technique can be extended to other inorganic
nanomaterials and will be useful in applications where arrays of
inorganic nanoparticles are desired.
Ring-like arrangements are revealed with iron oxide nanoparticles
prepared using two particle lithography.