Questions about the AFM with gold particles*

Hi !

Modern probe microscopes, such as scanning tunnelling (STM) and
scanning
force microscopy (SFM), not only allow high- resolution imaging of
surfaces but also offer the possibility of moving or manipulating
objects on the substrate.

Thanks to those new possibilities offered by the AFM, we are working
on
the deposit of thin film of gold on a DOW cylco-tene polymer.

We use this polymer because of the weak interfacial interaction it
has.

The deposit of the gold layer is obtained in a vacuum chamber by
evaporation due to a high bean (beam?) of electron.

Then, we get a substrate with a scattering of particles (nanorods
of gold) at the surface.

We use the AFM in contact mode with a silicon tip in order to make
images of the surface. We are able to make a 50-100 nanometer image in
good condition.

If we change the dc applied voltages, we are able to form some
clusters
or lines by sweeping the surface with the tip.

What we discovered is the trend of the particles to merge.

A spontaneous coalescence can be observed while sweeping the
particles.
This coalescence is aimed at formation of the nanowires.

We also discovered that a laser beam can be used to modify the
interfacial forces between the substrate and the particles.

As a result, it becomes easier to sweep the tip of the AFM at the
surface that enable the formation of clusters and nanorods.

What we would like to know is :

1.
What forces are involved in this process ?

2.
What are the interaction between the laser beam and the
particules ? Why the interfacial interactions decrease after a laser
irradiation ?

3.
Is there other people that are working on the same subject ?

4.
I=92m looking for web page (URL) related to this study.

5.
Does somebody knows how to set the AFM for better result in this
case ?

5.
I'm looking for your ideas or remarks=20


Thanks

Hi,

With atomic force microscopy (AFM), somebody investigated the deposition and growth of gold nanorods (with high aspect ratio) directly on silicon substrate; nanorods were also manipulated with AFM tip.

See:
1. Langmuir (2004), 20(26), 11301;
2. Langmuir (2004), 20(11), 4322.