Chemistry Reference
In-Depth Information
Table 11 Summary of key literature on the soft landing of AuNC ions onto surfaces
AuNC ion
Surface
Key findings
References
Au
+
Amorphous
carbon
An example of 'bottom-up synthesis' via ion
beam deposition, which requires
agglomeration. The ion beam energy
plays a key role in the resultant cluster
size
[
337
]
Au
x
+
(
x
¼
5,7,
27,33)
Amorphous
carbon
No significant fragmentation or agglomera-
tion of the clusters was observed
[
338
]
Au
250
+
Graphite
Clusters move on the surface but do not
always agglomerate when then touch
[
339
]
Au
x
+
Au(111)
Neither diffusion nor coalescence of the SL
AuNCs was detected
[
340
]
Au
x
+
(
x
¼
1-8)
Au
+
undergoes sintering. For
x
¼
2-8, SL
Au
x
are not mobile and do not sinter. The
SL clusters adopt a different shape to the
gas phase due to charge transfer from the
surface and ligation by the surface
TiO
2
(110)
[
341
]
Au
x
+
(
x
¼ 2-10)
SiO
2
/Si(111) and
Al
2
O
3
/ SiO
2
/
Si(111)
2D SL AuNCs undergo a structural change
on the surface from vertical into hori-
zontal orientations. The horizontal clus-
ters can then undergo diffusion and
agglomeration
[
342
]
Au
330
17
+
and
Au
10000
500
+
Amorphous
carbon
The role of temperature and cluster size on
agglomeration were studied. At higher
temperatures smaller clusters are more
mobile and agglomerate more rapidly
[
343
]
Au
x
+
Graphite
The role of background pressure of
agglomeration of NCs was examined
[
344
]
Au
11
L
5
3+a
SAMs
a
The cluster remains intact, but the SAM
used influences the charge state of
Au
11
L
5
n
+
: FSAM:
n
¼
3; COOH-SAM
n
¼
2, HSAM:
n
¼
1
[
345
]
Au
11
L
5
3+a
SAMs
a
The charge state of soft landed Au
11
L
5
n+
is
influenced by both the SAM and the
surface coverage. At higher coverages,
pronounced reduction is observed
[
346
]
Au
x
+
Silica
Photoelectron spectroscopy was used to
examine how the valence electronic
states changes as a function of cluster
size
[
347
]
Au
4
+
,Au
8
+
and
Au
3
Sr
+
MgO(100)
A review focussing on the role of oxide
support defects, cluster size dependence,
cluster structural fluxionality and impu-
rity doping on the catalytic properties of
size-selected metal clusters on surfaces
[
348
]
Au
x
+
(1
<
x
20) MgO(100)
Low-temperature oxidation of CO was
studied as a function of cluster size. Au
8
was found to be the smallest catalytically
active cluster
[
349
]
(continued)
