Supplemental information
Electric radiation mapping of silver/zinc oxide nanoantennas by using
electron holography
J. E Sanchez1, F. Mendoza Santoyo1*, J. Cantu Valle1, J. VelazquezSalazar1, M. José Yacaman1, F.J. González2, R. Diaz de Leon3 and A.
Ponce1
1
Department of Physics and Astronomy, University of Texas at San
Antonio, San Antonio, 78249, USA
2
Coordinación para la Innovación y la Aplicación de la Ciencia y la
Tecnología, Universidad Autónoma de San Luís Potosí, San Luis Potosí,
78210, México
3
Instituto Tecnológico de San Luis Potosí, San Luis Potosi, 78437, Mexico
Figure S1 shows images of the silver nanowires synthetized by the polyol method. The
silver nanowires were used as substrates for the self-assembling of the ZnO rods.
FIG. S1. Silver nanowires synthetized by polyol method using PVP. TEM images (a) bright field, (b) dark
field and SEM micrographs (c) and (d).
*
On sabbatical leave Centro de Investigaciones en Óptica, León Guanajuato, 37150, Mexico
Figure S2 shows a picture of the electron holography in-situ signal stimulation
experimental set up. The electrical signal is introduced using a shield wire that passes
through an insulator core in the electrical holder, and at the same time feeds the circuit loop
on the electric head chip (Fig. S2.A). That is, the pads on the electrical chip serve as an
electric path to introduce the modulated signal using the wave function generator G (Fig.
S2.C). The sample is deposited on the copper grid shown in Fig. S2.A. On the other hand,
for electron holography the biprism is biased at 60 V generating a hologram with space
fringes of 20 nm and field of view of 3.8 microns.
z
FIG. S2. Experimental set up for the external signal applied to the nanoantennas. (A) Sample holder showing
an amplified picture and the electrical chip used to transmit the electrical signal. (B) Biprism available in the
transmission electron microscope used for electron holography is indicated in the picture. (C) Signal
generator and its connection to the sample holder.
In Fig. S3 a single ZnO/Ag nanoantenna was simulated in two different orientations using
COMSOL Multiphysics which uses the Finite Element Method (FEM) to solve partial
differential equations under diverse boundary conditions. The simulations were performed
by considering the nanostructures as emitters, a current source was simulated flowing
through the silver nanowire and the E-field pattern near the nanostructure was recorded.
Matched boundary conditions were used in the FEM simulations and tetrahedral elements
were used to discretize the computational domain. In the simulated patterns a MHz
frequency range was used as in the experiment shown in the Figure 6 of the manuscript.
FIG. S3. Simulations of two different orientation of an individual nanoantenna stimulated in MHz range as
used in the experimental set up: (A) Pentagonal cross section view (B) lateral view.
Movies Captions
Movie S1: In-situ radiation pattern reconstructed by electron holography applying
an external signal from 1 to 10 MHz, using steps of 1MHz per second at constant
amplitude of 5 Vpp.
Movie S2: In-situ radiation pattern reconstructed by electron holography applying
an external signal using modulated amplitude from 1 to 5 V, using steps of 1 V per
second with a frequency constant of 1 MHz.