Supplementary information - 1
Spatially resolved energy dispersive x-ray spectroscopic method for in-situ evaluation of
mechanical properties during the growth of a C - Pt composite nanowire
Amit Banerjee and S. S. Banerjee
Department of Physics, Indian Institute of Technology Kanpur, Kanpur, 208016, India
Monte-Carlo simulation showing the secondary electron generation pattern from our carbon
nanowire core under electron beam irradiation:
We used primary electron (PEs) beam of 30 keV of energy to crack the Pt precursor gas molecules
adsorbed to the surface of the C nanowire core, as we have discussed in the paper. The PEs generate
secondary electrons (SEs) which inturn induces the cracking process. We carry our Monte-Carlo
simulation for electron trajectories to investigate the profile of SE generation from our C nanowire
core under the e-beam irradiation (energy = 30 keV).
The CASINO software (version 3)1 provides electron trajectories inside 3D samples of customisable
geometry (viz., one can create a virtual sample of appropriate shape, dimension and material
properties identical to the real sample), including trajectories of secondary electrons (SEs) (energy <
50 eV) and back-scattered electrons (BSEs) (energy > 50 eV). We perform the CASINO simulation
with 10000 primary electrons (PEs) of 15 keV energy falling at a 1 nm spot-size on the surface of a
virtual C nanowire of 203 nm diameter (i.e., identical to the actual C nanowire in Fig. 2(a) described
in the paper). We supress the trajectories of straggling PEs and BSEs inside the C nanowire in order to
highlight the SEs (green dots) generated by the e-beam irradiation in Fig. S1. From the distribution
shown in Fig. S1, it appears that the SEs are generated near the irradiation point as well as from the
rear surface of the nanowire. Thus, a scan of the C nanowire with the e-beam results in significant
generation of SE distribution around the circumference of the nanowire, which inturn causes a
deposition of the Pt from the adsorbed Pt precursor gas molecules. Therefore a uniform and axiallysymmetric (axis is along the length of the nanowire) Pt-shell deposition around the C nanowire core is
anticipated as the e-beam is scanned along the length of the nanowire.
Incident e-beam
(a)
(b)
FIG. S1. Image depicting the results of the CASINO simulation for electron trajectories around the C nanowire
core along the (a) cross-sectional view and (b) top view, where the green dots represent the secondary electrons.
The arrows represent the scan direction of the electron beam.
Reference:
1
H. Demers, N. P. Demers, A. Real Couture, D. Joly, M. Guilmain, N. D. Jonge, And D. Drouin, Scanning 33,
135–146 (2011).