Nano Res.
Electronic Supplementary Material
Laser generation of iron-doped silver nanotruffles with
magnetic and plasmonic properties
Vincenzo Amendola1 (), Stefano Scaramuzza1, Stefano Agnoli1, Gaetano Granozzi1, Moreno Meneghetti1,
Giulio Campo2, Valentina Bonanni2, Francesco Pineider2, Claudio Sangregorio2,3, Paolo Ghigna4, Stefano Polizzi5,
Piero Riello5, Stefania Fiameni6, and Luca Nodari6
1
Department of Chemical Sciences, Università di Padova, Padova I-35131, Italy
Department of Chemistry, University of Florence & INSTM, Florence I-50019, Italy
3
ICCOM-CNR, Sesto Fiorentino, Florence I-50019, Italy
4
Department of Chemistry, Università di Pavia, Pavia I-27100, Italy
5
Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari Venezia and INSTM UdR Venezia, Venezia-Mestre
I-30172, Italy
6
CNR – IENI, Padova I-35127, Italy
2
Supporting information to DOI 10.1007/s12274-015-0903-y
Figure S1 XRD pattern and Rietveld fit of bulk bimetallic Fe–Ag target exploited for LASiS of Fe–Ag NPs.
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Nano Res.
Figure S2 X-ray photoemission S 2p (a) and C 1s (b) peaks.
In case of the C 1s spectrum, there is no signal at the binding energy (BE) of carbides (283.0–283.6 eV) [S1],
suggesting that iron carbide is not present (Fig. 3(b)).
Table S1
Room temperature Mössbauer fitting parameters for sample M
Site
 (mm/s)
 / (mm/s)
1/2 (mm/s)
B (T)
A (%)
Attribution
Doublet 1
0.41(63)
0.67(14)
0.47(13)
\
38.5(56)
Superparamagnetic Fe(III)
Sextet 1
0.179(73)
0.106(67)
0.30(11)
20.03(51)
29(12)
Magnetically ordered Fe in
disordered Fe–Ag regions
Sextet 2
0.24(31)
0.00(24)
0.75(50)
28.1(21)
32(21)
Magnetically ordered Fe in
disordered Fe–Ag regions
(slightly richer in Fe)
The best fitting was obtained by means of three components: one doublet for the central absorption and two
broad sextets for the magnetically coupled component. The doublet, whose hyperfine parameters are typical
for Fe(III) in octahedral environment, could be ascribed to the presence of iron oxides which exhibits a room
temperature superparamagnetic behaviour at the Mössbauer time scale. The presence of Fe atoms in higher
oxidation state is in agreement with XPS measurements and with previous observations in this type of bimetallic
alloy produced as thin films [S2–S4]. Concerning the magnetically splitted components, both are compatible
with iron atoms in a bcc lattice, i.e. the signal is originated by iron-rich crystalline regions [S5, S6].
Figure S3 (a) EXAFS derivative spectra. (b) Fourier transformed EXAFS spectrum of the sample investigated in this work (black line),
and its fit (red line) according to the model of Table S2.
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Nano Res.
EXAFS oscillations are well visible above the noise level up to k = 11.5 Å–1 (structural parameters are reported
in Table S2), which gives a number of EXAFS independent points equal to 11.
Table S2 Fitting parameters of EXAFS spectrum. Value of fit index at minimum: 30%. r0 are the distances in metallic Fe and for Fe in
the tetrahedral site of the FeO spinel
Shell
N
Atom
r (Å)
σ2 (Å2)
r0 (Å)
1
4
O
1.78(4)
17(8) × 10–3
1.881
Fe fraction 0.3(1)
1
8
Fe/Ag
2.50(2)
7(2) × 10–3
2.483
2
6
Fe/Ag
2.89(2)
5(3) × 10–3
2.868
3
12
Fe/Ag
3.99(8)
2(1) × 10–2
4.056
Fe fraction 0.7(1)
Figure S4 View of the low field part of the hysteresis loops measured at 2.5 K after field cooling the sample from room temperature in
a 5 T magnetic field (red symbols) and with no applied field (blue symbols).
With no applied field cooling, the hysteresis loop is open with a coercive field of 28 mT and a reduced remnant
magnetization of 0.11. Upon field cooling the sample we observed an exchange field, 0HEx = 5.5 mT and a
coercive field, HC = 34 mT.
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Nano Res.
Figure S5 Temperature dependence of the magnetization measured with an applied field of 5 T.
Figure S6 OAS spectra of PEG-coated Fe-Ag NPs synthesized in ethanol (right, same as in Fig. 1(c)) and water (left) and redispersed
in water just after the synthesis (green line), and after the magnetic sorting in fractions M (magnetic, red line) and NM (non-magnetic, black
line). Collection yield is larger with the ethanol sample.
References
[S1] Wiltner, A.; Linsmeier, C. Formation of endothermic carbides on iron and nickel. Phys. Stat. Sol. (A) 2004, 201, 881–887.
[S2] Spizzo, F.; Angeli, E.; Bisero, D.; Da Re, A.; Ronconi, F.; Vavassori, P. Mössbauer investigation of sputtered FexAg100−x films.
J. Magn. Magn. Mater. 2004, 272–276, 1169–1170.
[S3] Roy, M. K.; Nambissan, P. M. G.; Verma, H. C. Structural, thermal stability and defect studies of Fe–Ag alloy prepared by
electrodeposition technique. J. All. Comp. 2002, 345, 183–188.
[S4] Jiraskova, Y.; Bursik, J.; Zivotsky, O.; Cuda, J. Influence of Fe2O3 on alloying and magnetic properties of Fe–Al. Mater. Sci. Eng.
B 2014, 186, 73–78.
[S5] Herr, U.; Jing, J.; Gonser, U.; Gleiter, H. Alloy effects in consolidated binary mixtures of nanometer-sized crystals investigated by
Mössbauer spectroscopy. Solid State Commun. 1990, 76, 197–202.
[S6] Rixecker, G. The difficulty of isolating grain boundary components in the Mössbauer spectra of ball-milled materials: Iron and
silver–iron alloys. Solid State Commun. 2002, 122, 299–302.
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