RSC Advances
PAPER
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View Journal  | View IssueMagnetic properaInstitute of Physics, E´cole polytechnique
Lausanne, Switzerland
bCenter for Quantum Nanoscience, Institut
Republic of Korea
cEmpa, Swiss Federal Laboratories for M
Du¨bendorf, Switzerland
dPhysik Department, Technische Universita¨t
eCNR-IOM, Laboratorio Nazionale TASC, I-3
fEuropean Synchrotron Radiation Facility, G
gSwiss Light Source, Paul Scherrer Institut, C
† Electronic supplementary informa
10.1039/c9ra06803a
‡ These authors contributed equally to th
Cite this: RSC Adv., 2019, 9, 34421
Received 28th August 2019
Accepted 16th September 2019
DOI: 10.1039/c9ra06803a
rsc.li/rsc-advances
This journal is © The Royal Society of Cties of on-surface synthesized
single-ion molecular magnets†
Katharina Diller, ‡a Aparajita Singha,‡ab Marina Pivetta, a Christian Wa¨ckerlin, ac
Raphael Hellwig,d Alberto Verdini,e Albano Cossaro, e Luca Floreano, e
Emilio Ve´lez-Fort,f Jan Dreiser, g Stefano Rusponi a and Harald Brune *a
Weperformon-surface synthesis of single-ionmolecularmagnets on anAg(111) surface and characterize their
morphology, chemistry, andmagnetism. The first molecule we synthesize is TbPc2 to enable comparison with
chemically synthesized and subsequently surface adsorbed species. We demonstrate the formation of TbPc2
with a yield close to 100% and show that on-surface synthesis leads to identical magnetic and morphological
properties compared to the previously studied chemically synthesized species. Moreover, exposure of the
surface adsorbed TbPc2 molecules to air does not modify their magnetic and morphological properties. To
demonstrate the versatility of our approach, we synthesize novel Tb double deckers using tert-butyl-
substituted phthalocyanine (tbu-2H-Pc). The Tb(tbu-Pc)2 molecules exhibit magnetic hysteresis and
therefore are the first purely on-surface synthesized single ion magnet.Introduction
Single molecule magnets (SMMs), and in particular single-ion
magnets (SIMs), i.e. molecular complexes hosting a single
magnetic atom, are promising building blocks for molecular
spintronics applications. Lanthanide-based SIMs have been
considered as prototypes for bits in high-density magnetic data
storage devices and in quantum information processing.1–10
Exploiting the SIMs in devices requires contacting them with an
electrode, while preserving the stable spin orientation and long
spin coherence time. Typically, SMMs are synthesized in solu-
tion by chemical means (hereaer referred to as ex vacuo
synthesized); however, transferring them onto a surface in
a clean and controlled environment is oen problematic. For
this purpose, themost appropriate route is thermal sublimation
onto the substrate of interest.11–14 More elaborate methods are
required for SMMs whose fragility prevents their thermal
sublimation, for example electrospray deposition.15,16fe´de´rale de Lausanne (EPFL), CH-1015
e for Basic Science (IBS), Seoul 03760,
aterials Science and Technology, 8600
Mu¨nchen, D-85748 Garching, Germany
4149 Trieste, Italy
renoble, France
H-5232 Villigen PSI, Switzerland
tion (ESI) available. See DOI:
is work.
hemistry 2019An alternative approach is the in situ synthesis of SIMs by on-
surface metalation. This method consists of depositing the
desired magnetic atoms onto a few layers of the free-base
molecular ligands directly adsorbed on the chosen substrate.
On-surface metalation of various free-base tetrapyrrole mole-
cules has been intensively studied in recent years, and the
procedures are well known for transition metal atoms.17–19
Depending on the element and the preparation conditions, the
reaction occurs at room temperature (RT),20 or requires
annealing.21 For the few known examples of lanthanide metal-
ation, the requirements are less evident. For tetraphenylpor-
phyrins (TPPs) (Er-TPP22 and Ce-TPP,23,24) metalation at room
temperature is controversial, while for the preparation of
cerium tetraphenylporphyrin double deckers (Ce(TPP)2),
annealing to 500 K was used.25 For these systems the occurrence
of the metalation process was demonstrated, but the magnetic
properties of the resulting molecules were not investigated.
Here we introduce the on-surface synthesis of a Tb double
decker SIM, i.e., bis(phthalocyaninato)terbium(III) (TbPc2).1,2
Room temperature (RT) deposition of Tb atoms on pristine
phthalocyanines (2H-Pc) adsorbed on Ag(111) gives a yield of
close to 100% TbPc2. Combining X-ray photoelectron spectros-
copy (XPS), X-ray absorption spectroscopy (XAS), X-ray magnetic
circular dichroism (XMCD), and scanning tunneling micros-
copy (STM), we demonstrate that the on-surface synthesized
TbPc2 possesses identical magnetic, chemical, and morpho-
logical properties to those observed for ex vacuo synthesized
TbPc2.8 Moreover, we demonstrate that the on-surface prepared
TbPc2 molecules are robust when exposed to ambient condi-
tions. Finally they form large-scale ordered arrays when
annealed to 570 K.RSC Adv., 2019, 9, 34421–34429 | 34421
Fig. 1 (a) Schematic of the experimental geometry and the definitions
of X-ray polarizations. (b) On-surface synthesized TbPc2: XAS with
circular polarizations, XMCD, XAS with linear polarizations and XLD at
the Tb M4,5 edges along with magnetization curves probed at the Tb
M5 edge (3.4 ML 2H-Pc/Ag(111) + 0.7 ML Tb, Tdep ¼ 300 K). (c) The
same for ex vacuo synthesized 0.3 ML TbPc2/Ag(100) from ref. 8.
(m0H ¼ 50 mT and 6.8 T for measurements with linear and circular
polarizations, respectively, m0Ḣ ¼ 2 T min1 for magnetization curves
measurements, T ¼ 3 K).
RSC Advances Paper
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View Article OnlineTo demonstrate the versatility of this method, we create
a novel double-decker SIM, namely Tb-(tbu-Pc)2 on Ag(111),
starting from tbu-2H-Pc, a Pc derivative with four bulky groups
attached to the main Pc structure. We show that also this novel
double-decker complex exhibits magnetic hysteresis, reminis-
cent of long spin relaxation times. This makes Tb-(tbu-Pc)2 one
of the very few SIMs discovered so far that exhibits a long spin
lifetime while being directly adsorbed on a metal substrate.
Results and discussion
We deposit Tb atoms on pristine 2H-Pc molecules adsorbed on
Ag(111) at RT. The most stringent test of whether we have suc-
ceeded in synthesising the TbPc2 target molecule with high yield
is to thoroughly characterize the magnetic properties. For this, we
use low-temperature (3 K) X-ray absorption spectroscopy (XAS)
and magnetic circular and linear dichroism (XMCD and XLD, see
scheme in Fig. 1a), at the Tb M4,5 edge (Fig. 1b), and compare the
results with the corresponding measurements on ex vacuo
synthesized TbPc2 deposited on Ag(100) (Fig. 1c).8 For comparison
among samples with different Tb coverages, all spectra are
normalized with respect to the total XAS peak area (see Methods).
The substantial XMCD signal indicates the presence of a large
magnetic moment at 6.8 T and 3 K. Moreover, the XMCD in
normal incidence is larger than that measured in grazing inci-
dence. This angular anisotropy, as well as the XLD signal
measured at 0.05 T, evidence the at-lying geometry of the
molecules with an out-of-plane easy magnetization axis, as also
reported for the case of ex vacuo synthesized TbPc2.8
The XMCD and XLD measurements observed for the on-
surface synthesized TbPc2 are very similar in shape and inten-
sity to the ones obtained for the ex vacuo synthesized TbPc2,
implying that all Tb atoms are incorporated into free-bases
during the metalation reaction. Any Tb le over would form
clusters on Ag(111) that have an in-plane easy axis, which would
result in a overall reduced XMCD intensity, and very different
multiplet features in both XAS and XMCD, see Fig. S1 (ESI†).
This enables us to clearly distinguish Tb clusters from meta-
lated molecules. Note that our XMCD and XLD spectra are very
similar to the ones reported for ex vacuo TbPc2 on Cu(100),4 on
Ag(100), MgO, h-BN/Ru(0001),8 and on graphene/SiC(0001).26
This shows that for these different substrates the Tb magnetic
ground state is the same, and that the molecules are at-lying.
Given the strongly different electronic characters of these
substrates, going from metallic to insulating, we can infer that
the TbPc2 hybridization with all these substrates is weak,
leaving the molecules intact and essentially undistorted. This
small inuence of the substrate also justies the fact that we
compare the on-surface synthesized molecules on Ag(111) with
the ex vacuo synthesized ones on Ag(100).
Ex vacuo synthesized TbPc2 exhibits slow magnetic relaxa-
tion leading to magnetic hysteresis.8 We perform the same
measurements to verify the quality of the TbPc2 prepared by on-
surface metalation. Magnetization curves are obtained by
recording the maximum of the XMCD signal at the Tb M5 edge
as a function of the external magnetic eld (Fig. 1b lower panel).
Notably our on-surface synthesized molecules exhibit the same34422 | RSC Adv., 2019, 9, 34421–34429magnetic hysteresis as reported for the ex vacuo synthesized
TbPc2/Ag(100) (Fig. 1c lower panel).
Further evidence for the success of the metalation reaction
comes from XPS and STM measurements. Fig. 2a (upper panel)
shows the N 1s XPS region measured on 1.9 ML 2H-Pc/Ag(111)This journal is © The Royal Society of Chemistry 2019
Fig. 2 (a) N 1s XPS spectra and corresponding fit for 1.9 ML pristine 2H-Pcmolecules (upper panel) and after deposition of 0.5 ML Tb, yielding 0.5
ML on-surface synthesized TbPc2 molecules (lower panel). Schematics of 2H-Pc and TbPc2 are shown as insets. For the case of TbPc2, only top
layer N atoms are highlighted. STM image of (b) 2H-Pc (Vt ¼ 2.0 V, It ¼ 20 pA, T ¼ 5 K), and (c)z0.4 ML on-surface synthesized TbPc2 (Vt ¼
2.0 V, It¼ 50 pA, T¼ 5 K); (d) same as (c) after 15min of annealing at 500 K (Vt¼2.0 V, It¼ 50 pA, T¼ 5 K). (e) Line profiles corresponding to the
line-cuts shown in (b), (c) and (d); (f), corresponding models.
Paper RSC Advances
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View Article Online(see Methods for the ML denition). It exhibits two well sepa-
rated peaks corresponding to the two differently bound N-
species: –N] (hereaer named as N for simplicity) and –NH–
(that we call NH).17,18 Peak N combines contributions from
iminic (central) and aza (outer) nitrogen since their core level
shis are very similar while the one of NH is clearly different.
Using Gaussian ts and constraining a 1 : 3 ratio as expected
from stoichiometry for the NH to N peak intensity,27–29 we nd
the energy position of the NH and N peaks at 400.2 eV and
398.6 eV, respectively (see Methods for details).
Deposition of Tb at RT leads to a reduction of the NH peak
intensity and to a concomitant broadening of the main peak, see
Fig. S2 (ESI†). The XPS spectrum aer 0.5 ML of Tb is shown in
Fig. 2a, lower panel. Tot these data, we have to introduce N–Tb as
the third N-related component. Positions of NH and N peaks were
kept xed at the values found for the free-base 2H-Pc. The
contribution from peak N was xed to the total contribution from
the N–Tb peak plus three times that of NH, as imposed by stoi-
chiometry. With this constraint, we identify the N–Tb component
at 398.1 eV. Its binding energy is lower than that of iminic nitrogen
and it is well below the energy range for transition metal coordi-
nated tetrapyrrole nitrogen species (e.g. 398.5–398.9 eV for Co-, Ni-,
Cu-, and Zn-TFcP30 and 398.7 eV for FePc28). This can be rational-
ized considering the signicantly higher reactivity of lanthanides.This journal is © The Royal Society of Chemistry 2019To gain further insights about the reaction products we
perform STM measurements. At RT the free-base molecules
assemble into well-ordered islands. As seen in Fig. 2b, at 1.5 ML
2H-Pc, the surface is completely covered with the rst layer of
free-base and extended, compact islands form in the second
layer. Aer depositing 0.4 ML of Tb (Fig. 2c), two species with
different apparent height h are observed, as shown in Fig. 2e.
The predominant (gray) features have the same apparent height
with respect to the free-base layer as the second-layer 2H-Pc
(h z 240 pm). They exhibit the pattern typical for TbPc2 con-
sisting of eight lobes with equivalent apparent heights, at vari-
ance with the non-homogeneous contrast observed on free-base
molecules in the second layer. Therefore we identify them as on-
surface synthesized TbPc2 embedded in the free-base layer (see
Fig. 2f).11,31,32 The brighter features, imaged with an apparent
height of 330 pm with respect to the underlying TbPc2 mole-
cules, are attributed to second layer TbPc2,11,33,34 although
formation of Tb2Pc3 cannot be excluded.35,36 Combining the
information obtained from XPS and STM with that from XAS,
XMCD, and XLD measurements, we conclude that the metal-
ation reaction leads to the formation of TbPc2 at RT.
From experiments with varying coverages of 2H-Pc and Tb,
we infer the following strategy to ensure that all Tb atoms are
incorporated in the molecules: (a) a ratio of Tb to 2H-Pc smallerRSC Adv., 2019, 9, 34421–34429 | 34423
RSC Advances Paper
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View Article Onlinethan the target stoichiometry of 0.5; (b) an amount of 2H-Pc
between 2 and 4 ML. This strategy leaves an excess of unreacted
molecules on the surface as shown in Fig. 2. These molecules
have no effect on the observed magnetic properties since the
lateral magnetic interactions among TbPc2 molecules are
negligible.8 Therefore slightly diluting TbPc2 with unreacted
molecules does not inuence the observed magnetic properties.
Tb in excess results in the concomitant formation of TbPc2 and
Tb clusters visible as bright spots in the STM images shown in
Fig. S3 (ESI†). The presence of clusters is also revealed by the
strong reduction of the XMCD signal acquired at normal inci-
dence, associated with a reduction and inversion of the XLD
signal, see Fig. S4 (ESI†).
The STM image in Fig. 2c shows that for RT preparation the
sample morphology is quite rough and a few unreacted second
layer free-base molecules coexist with reacted molecules. They
are mobile under the inuence of the STM tip as seen in the
lower part of the image, where the molecular structure is fuzzy.
Annealing at 500 K for 15 min produces a rearrangement of
the molecules leading to an increased spatial order (Fig. 2d).
Note that the second layer TbPc2 molecules are still present as
also demonstrated by the line prole. The typical morphology
aer RT deposition is also evident in samples prepared with
a larger amount of molecules. For a sample consisting of 2.7 MLFig. 3 (a) STM image showing irregular arrangement of on-surface synth
annealing at 570 K for 30 min, the TbPc2 molecules organize in large ord
0.8 ML Tb). (d) Zoom into the marked area in (c) showing the perfectly o
crosses indicate the molecular orientation; unit cell is shown as a square
TbPc2 packing with respect to the Ag(111) substrate.
34424 | RSC Adv., 2019, 9, 34421–34429of 2H-Pc plus 0.8 ML of Tb, the large-scale image in Fig. 3a
shows the species already identied in Fig. 2, piled into addi-
tional layers. Annealing at 570 K for 30 min leads to partial
desorption of unreacted free-base molecules, to segregation of
the different molecular species and to a dense, ordered packing
of the TbPc2. Such long-range ordering of TbPc2 is evident from
the middle terrace of Fig. 3b, the le terrace of Fig. 3c, and the
corresponding zoom shown in Fig. 3d. In the latter image the
TbPc2 molecules appear with alternating bright/dark
contrast.32,33,37,38 This is even more evident in Fig. 3e showing
high resolution images of the same TbPc2 island acquired with
two tip terminations yielding different submolecular appear-
ances. From the orientation of the lobes and of the resulting
pattern we deduce that the bright/dark contrast corresponds to
a difference of about 10 in the azimuthal orientation of the
molecules as highlighted by the crosses superimposed onto the
molecule assembly. A tentative model of the molecular
arrangement with respect to the Ag(111) surface is shown in
Fig. 3f. The unit cell is a 2.02 nm-side square, yielding a mole-
cule–molecule distance of 1.43 nm, fully compatible with
already reported ordered assemblies of TbPc2 molecules on
surfaces.8,33,37,38 Note that from our data we cannot conclude
whether the whole molecule38 or only the upper Pc ligand37 is
rotated.esized TbPc2 molecules (2.7 ML 2H-Pc/Ag(111) + 0.8 ML Tb). (b) Upon
ered islands. (c) As in (b) for a different sample (2.2 ML 2H-Pc/Ag(111) +
rdered TbPc2 lattice. (e) High-resolution STM images; white and black
(Vt ¼ 2.0 V, It ¼ 20 pA, T ¼ 5 K for all panels). (f) Model showing the
This journal is © The Royal Society of Chemistry 2019
Paper RSC Advances
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View Article OnlineRare earths are very reactive. However, one of the many
advantages of TbPc2 comes from Tb being sandwiched between
two Pc macrocycles which potentially protects it from contam-
ination. In order to verify this in our on-surface synthesized
TbPc2, we performed XAS, XMCD, and XLD measurements on
a sample before and aer exposing it to ambient conditions. As
demonstrated in Fig. 4a and b, the spectroscopic ngerprints,
i.e., the shape of the XAS prole and the amplitude of the XMCD
and XLD proles measured at the Tb M4,5 edges, remain
unmodied. Moreover, corresponding STM measurements
reveal identical appearances of the molecules before and aer
the exposure to air, proving the chemical robustness of the on-
surface synthesized SIMs (Fig. 4c and d).
The mere reproduction of already known compounds is not
the nal goal of on-surface metalation. Ideally, one would aim at
the creation of novel molecules that were not produced by ex
vacuo synthesis, in particular, species that are potentially difficultFig. 4 XAS with circular polarizations, XMCD, XAS with linear polari-
zations, and XLD measured at the Tb M4,5 edge (a) before and (b) after
exposure to ambient conditions for 1 hour (2.3 ML 2H-Pc/Ag(111) + 0.4
ML Tb; m0H ¼ 100 mT and 8.0 T for measurements with linear and
circular polarizations, respectively, T ¼ 6 K). Representative STM
images are shown in (c) and (d), respectively (2.7 ML 2H-Pc/Ag(111) +
0.8 ML Tb; Vt ¼ 2.0 V, It ¼ 20 pA, T ¼ 5 K).
This journal is © The Royal Society of Chemistry 2019to adsorb on surfaces as a whole. To prove the versatility of our
approach, we create a novel double decker complex starting from
a different phthalocyanine free-base. It is known that the met-
alation of tetrapyrrole molecules with on-top deposited metal
atoms does not depend on the peripheral substituents.17 There-
fore interesting candidates are molecules with the same central
macrocycle but with peripheral groups that can possibly increase
the distance between magnetic atom and supporting substrate,
reducing the hybridization of the metal ion with the substrate
and decoupling it from substrate phonons and electrons. We
chose tbu-2H-Pc as the free-base since it has four additional
bulky tert-butyl (tbu) groups attached to themain phthalocyanine
structure (Fig. 5a). Similar to the case of 2H-Pc, we deposit Tb
atoms on tbu-2H-Pc directly adsorbed on Ag(111) at RT. The
combined XAS and STM results presented in Fig. 5 and 6
demonstrate the formation of Tb(tbu-Pc)2 molecules.
The magnetization curves in Fig. 5c evidence that this new
compound also exhibits magnetic hysteresis. There are only very
few SIMs that exhibit hysteresis being in direct contact withFig. 5 (a) Schematic of tbu-2H-Pc and Tb(tbu-Pc)2. (b) XAS, XMCD,
and XLD probed at the Tb M4,5 edges and (c) magnetization curve
probed at the Tb M5 edge (3.7 ML tbu-2H-Pc/Ag(111) + 0.8 ML Tb;
m0H ¼ 50 mT and 6.8 T for measurements with linear and circular
polarizations, respectively, m0Ḣ ¼ 2 T min1 for magnetization curves
measurements, T ¼ 3 K).
RSC Adv., 2019, 9, 34421–34429 | 34425
Fig. 6 STM images of (a) Tb(tbu-Pc)2 embedded in a tbu-2H-Pc layer after RT deposition of Tb on tbu-2H-Pc molecules; (b) after annealing at
570 K for 30 min. Left terraces: mainly free-base molecules, right terrace: large-scale ordered islands of Tb(tbu-Pc)2; (inset) FFT obtained from
a region exclusively covered by Tb(tbu-Pc)2. (c) High-resolution STM images of different regions of the annealed sample. Top: tbu-2H-Pc
molecules; the cyan circles highlight a single tbu-2H-Pcmolecule in the assembly. Bottom: Tb(tbu-Pc)2 molecules; the yellow dots in the lower-
right corner indicate the center of the molecules and serve as a guide to the eye. Brighter molecules are second-layer Tb(tbu-Pc)2 (1.8 ML tbu-
2H-Pc/Ag(111) + 0.6 ML Tb; Vt ¼ 2.0 V, It ¼ 50 pA, T ¼ 5 K).
RSC Advances Paper
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View Article Onlinea metal surface. This newly synthesized molecule, Tb(tbu-Pc)2, is
one of them. The environment of the Tb atom, sandwiched
between twomacrocycles in both TbPc2 and Tb(tbu-Pc)2, generates
the same crystal eld thus suggesting an identical ground state for
the Tb atom in the two compounds. However, in comparison with
TbPc2, the reduced XLD amplitude and XMCD angular anisotropy
hint at a distribution of canted easy axes due to adsorption of the
Tb(tbu-Pc)2 molecules with a tilt angle between the macrocycles
and the substrate surface. This interpretation is supported by the
STM image of Fig. 6a showing randomly dispersed Tb(tbu-Pc)2
molecules embedded in the tbu-2H-Pc rst layer, characterized by
an irregular appearance of the lobes.
Annealing at 570 K for 30 min induces segregation of the
different molecular species resulting in an ordered arrange-
ment of the Tb(tbu-Pc)2 visible on the right-hand terrace in
Fig. 6b, and partial desorption of the unreacted molecules (le-
hand terraces). The upper panel of Fig. 6c shows a terrace
partially covered by tbu-Pc molecules, each displaying four-
protrusions.39 The bottom panel of Fig. 6c shows that the
Tb(tbu-Pc)2 islands have a few second layer Tb(tbu-Pc)2
appearing as the brightest objects, similar to the morphology
observed for the annealed TbPc2. The Tb(tbu-Pc)2 molecules
self-assemble into a hexagonal structure as evident from the
FFT pattern obtained from a large scale region covered exclu-
sively by Tb(tbu-Pc)2 (inset in Fig. 6b). In Fig. 6c-bottom, the
yellow dots mark the center of the molecules, revealing that the
structure is not fully regular. The presence of different
regioisomers of the free-base can explain this imperfect spatial
order.40 The average real space periodicity of 2.0 nm is 40%
larger than the one observed for TbPc2, as expected from the
larger molecule size.
Summary and conclusions
We combined X-ray photoemission and absorption spectros-
copy with scanning tunnelling microscopy to show the34426 | RSC Adv., 2019, 9, 34421–34429successful on-surface synthesis of the TbPc2 SIM at room
temperature on Ag(111). These molecules show the same
magnetic properties as their ex vacuo synthesized twins and
exhibit magnetic hysteresis at 3 K. The metalation reaction is
further evidenced by XPS, where exposure of 2H-Pc/Ag(111) to
Tb at room temperature leads to a decrease of the NH compo-
nents and the emergence of a N–Tb component at 398.1 eV.
STM shows that the deposition at room temperature leads to
a random distribution of double deckers. Annealing to 570 K for
30 min promotes long range diffusion of the on-surface
synthesized double deckers, leading to large-scale ordered
islands, very similar to those observed for ex vacuo synthesized
TbPc2/Ag(100). We show the robustness of the magnetic prop-
erties of TbPc2/Ag(111) towards exposure to air. Moreover, we
demonstrate the on-surface synthesis of Tb(tbu-Pc)2/Ag(111)
which is the rst solely on-surface synthesized single-ion
magnet exhibiting magnetic hysteresis when in direct contact
with a metal surface. The successful on-surface synthesis of
TbPc2 and Tb(tbu-Pc)2 thus opens a promising route for
creating novel rare-earth based single ion magnets.
Methods
Sample preparation
The Ag(111) single crystal was cleaned by repeated cycles of
sputtering with Ar+ ions and annealing to 750–770 K. 2H-Pc and
tbu-2H-Pc molecules were obtained from Sigma Aldrich with
98% and 85% purity respectively. The molecules were sublimed
from a thermally heated quartz crucible (2H-Pc at 570 K and
tbu-2H-Pc at 590 K) onto the substrate maintained at room
temperature. One ML of 2H-Pc molecules is dened as one
complete close-packed layer in direct contact with the substrate.
The Tb coverage was determined from the XAS area at the Tb
M4,5 edges, based on another rare-earth metal reference (Er on
Pt).8,41 Here, one ML of Tb refers to the ideal coverage of one Tb
atom per rst-layer 2H-Pc molecule. Therefore, one ML ofThis journal is © The Royal Society of Chemistry 2019
Paper RSC Advances
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View Article Onlinesynthesized TbPc2 implies two ML of 2H-Pc. We used the XLD
area at the N K-edge of a sub-monolayer of ex vacuo synthesized
TbPc2 molecules, where the Tb to N ratio is dened by the
molecular structure, to determine the corresponding amount of
2H-Pc molecules. The use of the XLD allows to get rid of the
dominant background over the weak XAS N K-edge signal.
Tb M4,5-edge XAS/XMCD/XLD
The X-ray absorption spectra were measured at the EPFL/PSI X-
Treme beamline42 of the Swiss Light Source and at the beamline
ID32 of the European Synchrotron Radiation Facility by recording
the sample drain current in total electron yield mode. Measure-
ment settings were the same as those reported in ref. 8. The
amount of deposited 2H-Pc modies the Tb M4,5 background.
Therefore, in order to compare the data obtained from samples
with varied 2H-Pc coverage measured during different experi-
mental sessions, we subtracted a polynomial prole and obtained
a at background for all energies apart from the M5 and M4 peak
regions. All spectra are normalized to the total XAS dened as the
total absorption s+ + s for circular polarizations and sv + sh for
linear polarizations.
XPS
The XPS data were recorded at the ALOISA beamline at Elettra.
The molecular coverage was controlled via a quartz microbal-
ance where the deposition parameters were known from other
tetrapyrrole experiments performed at this beamline.43,44 The N
1s spectra were recorded at a photon energy of 500 eV. The
energy scale was calibrated against the Ag 3d5/2 line at 386.3 eV.
Spectra of the Ag 3d region were measured each time directly
aer the acquisition of N 1s spectra.45 Shirley background was
subtracted from all raw data. Fitting of the N 1s region was done
using Gaussian curves to avoid the introduction of additional
free parameters in Voigt curves. Quantitative analysis from such
tting is complicated since even for the unreacted 2H-Pc
molecules on a perfectly subtracted background, the spectrum
should be tted with at least four peaks, (a) the pyrrolic (NH)
species (green), (b) the iminic (central N) species (blue), (c) the
aza (outer N) species (blue), and (d) the shake-up peak. For
metalated molecules additional three peaks should be
included: (a) the metal coordinated species (N–Tb) (orange), (b)
the aza (outer N) species, and (c) the shake-up peak. In prin-
ciple, this number should be doubled due to different rst and
second layer contributions. As using such a large amount of
peaks would overdetermine the available data, and to ensure
comparability with the results from the literature,28,46 the
spectra in Fig. 2a were tted with three or ve peaks. The
underlying assumptions are as follows: (i) the 0.1–0.2 eV shi46
between rst and second layer is neglected and (ii) the shi of
0.35 eV (ref. 47) between iminic and aza nitrogen atoms is
neglected for both 2H-Pc as well as for TbPc2.
The top panel of Fig. 2a includes three components: the N,
NH, and a shake-up peak of the main peak N. This shake-up
peak has 2% of the total area and the total contribution from
peak N (combined intensity of N and its shake-up) is con-
strained to be three times that of the NH peak, followingThis journal is © The Royal Society of Chemistry 2019stoichiometry. For the metalated case (Fig. 2b), we have intro-
duced two additional components, namely N–Tb and its shake
up. For the metalated molecules, best t was obtained when the
combined shake-up area was 4% of the total area. For a given set
of data, the FWHM were required to be the same for all species.
From the XPS ts, we obtained the total area under the N,
NH, and N–Tb peak. We use this information to extract the Tb
coverage. Dening a as the fraction of the free-base 2H-Pc that
forms double deckers, we deduce a ¼ DðN TbÞ
2DðNHÞ þ DðN TbÞ,
following stoichiometry. Here D denes the area under the
corresponding peak. Finally the coverage of the formed double
deckers (and therefore that of deposited Tb) is calculated as aS/
2, where S is the amount of free-base deposited on Ag(111) in
ML. For the lower panel in Fig. 2a, a ¼ 0.53.STM
The STM images were recorded in constant current mode at 5 K
using a W tip.48 STM images of on-surface synthesized TbPc2 on
Ag(111) were acquired for samples with different coverages of
2H-Pc molecules and Tb atoms. Bias voltages indicated in the
gure captions correspond to the sample potential. For the STM
measurements, we rst calibrated the Tb coverage by depositing
Tb directly on Ag(111) and determining the covered area. The
proportion of observed metalated molecules follows from this
calibration.Conflicts of interest
There are no conicts to declare.Acknowledgements
K. D. acknowledges support from the EPFL Fellows program co-
funded by Marie Curie, FP7 grant agreement no. 291771. C. W.,
J. D. and A. S. gratefully acknowledge funding by the Swiss National
Science Foundation (Grants PZ00P2_142474 and 200020_157081).
Beamtimes at Elettra (beamline: ALOISA), the Swiss Light Source
(beamline: X-Treme), and the European Synchrotron Radiation
Facility (beamline: ID32) are gratefully acknowledged. R. H.
received funding from the Institute of Advances Studies of TU
Munich. We thank Andrea Fondacaro (ID:32, European Synchro-
tron Radiation Facility) for technical support.Notes and references
1 N. Ishikawa, M. Sugita, T. Ishikawa, S. Koshihara and Y. Kaizu,
Lanthanide Double-Decker Complexes Functioning as
Magnets at the Single-Molecular Level, J. Am. Chem. Soc.,
2003, 125, 8694–8695, DOI: 10.1021/ja029629n.
2 N. Ishikawa, M. Sugita, T. Ishikawa, S. Koshihara and
Y. Kaizu, Mononuclear Lanthanide Complexes with a Long
Magnetization Relaxation Time at High Temperatures: A
New Category of Magnets at the Single-Molecular Level, J.
Phys. Chem. B, 2004, 108, 11265–11271, DOI: 10.1021/
jp0376065.RSC Adv., 2019, 9, 34421–34429 | 34427
RSC Advances Paper
O
pe
n 
A
cc
es
s A
rti
cl
e.
 P
ub
lis
he
d 
on
 2
5 
O
ct
ob
er
 2
01
9.
 D
ow
nl
oa
de
d 
on
 1
1/
29
/2
01
9 
6:
49
:3
1 
A
M
. 
 
Th
is 
ar
tic
le
 is
 li
ce
ns
ed
 u
nd
er
 a
 C
re
at
iv
e 
Co
m
m
on
s A
ttr
ib
ut
io
n-
N
on
Co
m
m
er
ci
al
 3
.0
 U
np
or
te
d 
Li
ce
nc
e.
View Article Online3 M. Affronte, F. Troiani, A. Ghirri, A. Candini, M. Evangelisti,
V. Corradini, S. Carretta, P. Santini, G. Amoretti, F. Tuna,
G. Timco and R. E. P. Winpenny, Single molecule magnets
for quantum computation, J. Phys. D: Appl. Phys., 2007, 40,
2999–3004, DOI: 10.1088/0022-3727/40/10/S01.
4 S. Stepanow, J. Honolka, P. Gambardella, L. Vitali,
N. Abdurakhmanova, T.-C. Tseng, S. Rauschenbach, S. L. Tait,
V. Sessi, S. Klyatskaya, M. Ruben and K. Kern, Spin and
Orbital Magnetic Moment Anisotropies of Monodispersed
Bis(Phthalocyaninato)Terbium on a Copper Surface, J. Am.
Chem. Soc., 2010, 132, 11900–11901, DOI: 10.1021/ja105124r.
5 R. Vincent, S. Klyatskaya, M. Ruben, W. Wernsdorfer and
F. Balestro, Electronic read-out of a single nuclear spin
using a molecular spin transistor, Nature, 2012, 488, 357–
360, DOI: 10.1038/nature11341.
6 S. Thiele, F. Balestro, R. Ballou, S. Klyatskaya, M. Ruben and
W. Wernsdorfer, Electrically driven nuclear spin resonance
in single-molecule magnets, Science, 2014, 344, 1135–1138,
DOI: 10.1126/science.1249802.
7 J. Dreiser, Molecular lanthanide single-ion magnets: from
bulk to submonolayers, J. Phys.: Condens. Matter, 2015, 27,
183203, DOI: 10.1088/0953-8984/27/18/183203.
8 C. Wa¨ckerlin, F. Donati, A. Singha, R. Baltic, S. Rusponi,
K. Diller, F. Patthey, M. Pivetta, Y. Lan, S. Klyatskaya,
M. Ruben, H. Brune and J. Dreiser, Giant Hysteresis of
Single-Molecule Magnets Adsorbed on a Nonmagnetic
Insulator, Adv. Mater., 2016, 28, 5195–5199, DOI: 10.1002/
adma.201506305.
9 C. A. P. Goodwin, F. Ortu, D. Reta, N. F. Chilton and D. P. Mills,
Molecular magnetic hysteresis at 60 kelvin in dysprosocenium,
Nature, 2017, 548, 439–442, DOI: 10.1038/nature23447.
10 F.-S. Guo, B. M. Day, Y.-C. Chen, M.-L. Tong,
A. Mansikkama¨ki and R. A. Layeld, A Dysprosium
Metallocene Single-Molecule Magnet Functioning at the
Axial Limit, Angew. Chem., Int. Ed., 2017, 56, 1–6, DOI:
10.1002/anie.201705426.
11 K. Katoh, Y. Yoshida, M. Yamashita, H. Miyasaka,
B. K. Breedlove, T. Kajiwara, S. Takaishi, N. Ishikawa,
H. Isshiki, Y. F. Zhang, et al., Direct Observation of
Lanthanide(III)-Phthalocyanine Molecules on Au(111) by
Using Scanning Tunneling Microscopy and Scanning
Tunneling Spectroscopy and Thin-Film Field-Effect
Transistor Properties of Tb(III)- and Dy(III)-Phthalocyanine
Molecules, J. Am. Chem. Soc., 2009, 131, 9967–9976, DOI:
10.1021/ja902349t.
12 L. Malavolti, V. Lanzilotto, S. Ninova, L. Poggini, I. Cimatti,
B. Cortigiani, L. Margheriti, D. Chiappe, E. Otero,
P. Sainctavit, F. Totti, A. Cornia, M. Mannini and
R. Sessoli, Magnetic Bistability in a Submonolayer of
Sublimated Fe4 Single-Molecule Magnets, Nano Lett., 2015,
15, 535–541, DOI: 10.1021/nl503925h.
13 E. Kie, M. Mannini, K. Bernot, X. Yi, A. Amato, T. Leviant,
A. Magnani, A. Prokscha, T. Suter, R. Sessoli and
Z. Salman, Robust Magnetic Properties of a Sublimable
Single-Molecule Magnet, ACS Nano, 2016, 10, 5663–5669,
DOI: 10.1021/acsnano.6b01817.34428 | RSC Adv., 2019, 9, 34421–3442914 J. Dreiser, G. E. Pacchioni, F. Donati, L. Gragnaniello,
A. Cavallin, K. S. Pedersen, J. Bendix, M. Delley, B. Pivetta,
S. Rusponi and H. Brune, Out-of-Plane Alignment of
Er(trensal) Easy Magnetization Axes Using Graphene, ACS
Nano, 2016, 10, 2887–2892, DOI: 10.1021/acsnano.5b08178.
15 S. Kahle, Z. Deng, N. Malinowski, C. Tonnoir, A. Forment-
Aliaga, N. Thontasen, G. Rinke, D. Le, V. Turkowski,
T. S. Rahman, S. Rauschenbach, M. Ternes and K. Kern,
The Quantum Magnetism of Individual Manganese-12-
Acetate Molecular Magnets Anchored at Surfaces, Nano
Lett., 2012, 12, 518–521, DOI: 10.1021/nl204141z.
16 L. Gragnaniello, F. Paschke, P. Erler, P. Schmitt, N. Barth,
S. Simon, H. Brune, S. Rusponi and M. Fonin, Uniaxial 2D
Superlattice of Fe4 Molecular Magnets on Graphene, Nano
Lett., 2017, 17, 7177–7182, DOI: 10.1021/
acs.nanolett.6b05105.
17 K. Diller, A. C. Papageorgiou, F. Klappenberger, F. Allegretti,
J. V. Barth and W. Auwa¨rter, In vacuo interfacial tetrapyrrole
metallation, Chem. Soc. Rev., 2016, 45, 1629–1656, DOI:
10.1039/c5cs00207a.
18 J. M. Gottfried, Surface chemistry of porphyrins and
phthalocyanines, Surf. Sci. Rep., 2015, 70, 259–379, DOI:
10.1016/j.surfrep.2015.04.001.
19 H. Marbach, Surface-Mediated in Situ Metalation of
Porphyrins at the Solid – Vacuum Interface, Acc. Chem.
Res., 2015, 48, 2649–2658, DOI: 10.1021/
acs.accounts.5b00243.
20 J. M. Gottfried, K. Flechtner, A. Kretschmann, T. Lukasczyk
and H.-P. Steinru¨ck, Direct Synthesis of a Metalloporphyrin
Complex on a Surface, J. Am. Chem. Soc., 2006, 128, 5644–
5645, DOI: 10.1021/ja0610333.
21 T. E. Shubina, H. Marbach, K. Flechtner, A. Kretschmann,
N. Jux, F. Buchner, H. Steinru¨ck, T. Clark and
J. M. Gottfried, Principle and Mechanism of Direct
Porphyrin Metalation: Joint Experimental and Theoretical
Investigation, J. Am. Chem. Soc., 2007, 129, 9476–9483,
DOI: 10.1021/ja072360t.
22 M. Nardi, R. Verucchi, R. Tubino and S. Iannotta, Activation
and control of organolanthanide synthesis by supersonic
molecular beams: Erbium-porphyrin test case, Phys. Rev. B:
Condens. Matter Mater. Phys., 2009, 79, 125404–125409,
DOI: 10.1103/PhysRevB.79.125404.
23 A. Weber-Bargioni, J. Reichert, A. P. Seitsonen, W. Auwa¨rter,
A. Schiffrin and J. V. Barth, Interaction of Cerium Atoms with
Surface-Anchored Porphyrin Molecules, J. Phys. Chem. C,
2008, 112, 3453–3455, DOI: 10.1021/jp076961i.
24 F. Bischoff, K. Seufert, W. Auwa¨rter, A. P. Seitsonen, D. Heim
and J. V. Barth, Metalation of Porphyrins by Lanthanide
Atoms at Interfaces: Direct Observation and Stimulation of
Cerium Coordination to 2H-TPP/Ag(111), J. Phys. Chem. C,
2018, 122, 5083–5092, DOI: 10.1021/acs.jpcc.7b10363.
25 D. E´cija, W. Auwa¨rter, S. Vijayaraghavan, K. Seufert,
F. Bischoff, K. Tashiro and J. V. Barth, Assembly and
Manipulation of Rotatable Cerium Porphyrinato Sandwich
Complexes on a Surface, Angew. Chem., Int. Ed., 2011, 50,
3872–3877, DOI: 10.1002/anie.201007370.This journal is © The Royal Society of Chemistry 2019
Paper RSC Advances
O
pe
n 
A
cc
es
s A
rti
cl
e.
 P
ub
lis
he
d 
on
 2
5 
O
ct
ob
er
 2
01
9.
 D
ow
nl
oa
de
d 
on
 1
1/
29
/2
01
9 
6:
49
:3
1 
A
M
. 
 
Th
is 
ar
tic
le
 is
 li
ce
ns
ed
 u
nd
er
 a
 C
re
at
iv
e 
Co
m
m
on
s A
ttr
ib
ut
io
n-
N
on
Co
m
m
er
ci
al
 3
.0
 U
np
or
te
d 
Li
ce
nc
e.
View Article Online26 G. Serrano, E. Velez-Fort, I. Cimatti, B. Cortigiani, L. Malavolti,
D. Betto, A. Ouerghi, N. B. Brookes, M. Mannini and R. Sessoli,
Magnetic bistability of a TbPc2 submonolayer on a graphene/
SiC(0001) conductive electrode, Nanoscale, 2018, 10, 2715,
DOI: 10.1039/c7nr08372f.
27 S. Kera, M. Casu, K. Bauchspieß, D. Batchelor, T. Schmidt
and E. Umbach, Growth mode and molecular orientation
of phthalocyanine molecules on metal single crystal
substrates: A NEXAFS and XPS study, Surf. Sci., 2006, 600,
1077–1084, DOI: 10.1016/j.susc.2005.12.042.
28 Y. Bai, F. Buchner, M. T. Wendahl, I. Kellner, A. Bayer,
H.-P. Steinru¨ck, H. Marbach and J. M. Gottfried, Direct
Metalation of a Phthalocyanine Monolayer on Ag(111) with
Coadsorbed Iron Atoms, J. Phys. Chem. C, 2008, 112, 6087–
6092, DOI: 10.1021/jp711122w.
29 Y. Alfredsson, B. Brena, K. Nilson, J. A˚hlund, L. Kjeldgaard,
M. Nyberg, Y. Luo, N. Ma˚rtensson, A. Sandell, C. Puglia and
H. Siegbahn, Electronic structure of a vapor-deposited
metal-free phthalocyanine thin lm, J. Chem. Phys., 2005,
122, 214723, DOI: 10.1063/1.1924539.
30 V. N. Nemykin, P. Galloni, B. Floris, C. D. Barrett, R. G. Hadt,
R. I. Subbotin, A. G. Marrani, R. Zanoni and N. M. Loim,
Metal-free and transition-metal tetraferrocenylporphyrins
part 1: synthesis, characterization, electronic structure,
and conformational exibility of neutral compounds,
Dalton Trans., 2008, 4233–4246, DOI: 10.1039/b805156a.
31 S. Fahrendorf, N. Atodiresei, C. Besson, V. Caciuc, F. Matthes,
S. Blu¨gel, P. Ko¨gerler, D. E. Bu¨rgler and C. M. Schneider,
Accessing 4f-states in single-molecule spintronics, Nat.
Commun., 2013, 4, 2425, DOI: 10.1038/ncomms3425.
32 T. Komeda, K. Katoh and M. Yamashita, Double-decker
phthalocyanine complex: Scanning tunneling microscopy
study of lm formation and spin properties, Prog. Surf.
Sci., 2014, 89, 127–160, DOI: 10.1016/j.progsurf.2014.03.001.
33 Y. He, Y. Zhang, I.-P. Hong, F. Cheng, X. Zhou, Q. Shen, J. Li,
Y. Wang, J. Jiang and K. Wu, Low-temperature scanning
tunneling microscopy study of double-decker DyPc2 on Pb
Surface, Nanoscale, 2014, 6, 10779–10783, DOI: 10.1039/
C4NR02863E.
34 G. Serrano, S. Wiespointner-Baumgarthuber, S. Tebi,
S. Klyatskaya, M. Ruben, R. Koch and S. Mu¨llegger, Bilayer
of Terbium Double-Decker Single-Molecule Magnets, J. Phys.
Chem. C, 2016, 120, 13581, DOI: 10.1021/acs.jpcc.6b03676.
35 H. Isshiki, J. Liu, K. Katoh, M. Yamashita, H. Miyasaka,
B. K. Breedlove, S. Takaishi and T. Komeda, Scanning
Tunneling Microscopy Investigation of
Tris(phthalocyaninato)yttrium Triple-Decker Molecules
Deposited on Au(111), J. Phys. Chem. C, 2010, 114, 12202,
DOI: 10.1021/jp101349v.
36 J. Hellerstedt, A. Cahl´ık, M. Sˇvec, B. de la Torre, M. Moro-
Lagares, T. Chutora, B. Papousˇkova´, G. Zoppellaro,
P. Mutombo, M. Ruben, R. Zborˇil and P. Jelinek, On-
surface structural and electronic properties of
spontaneously formed Tb2Pc3 single molecule magnets,
Nanoscale, 2018, 10, 15553, DOI: 10.1039/c8nr04215b.
37 T. Komeda, H. Isshiki, J. Liu, Y.-F. Zhang, N. Lorente,
K. Katoh, B. K. Breedlove and M. Yamashita, ObservationThis journal is © The Royal Society of Chemistry 2019and electric current control of a local spin in a single-
molecule magnet, Nat. Commun., 2011, 2, 217, DOI:
10.1038/ncomms1210.
38 Z. Deng, S. Rauschenbach, S. Stepanow, S. Klyatskaya,
M. Ruben and K. Kern, Self-assembly of
bis(phthalocyaninato)terbium on metal surfaces, Phys. Scr.,
2015, 90, 098003, DOI: 10.1088/0031-8949/90/9/098003.
39 Z. T. Deng, H. M. Guo, W. Guo, L. Gao, Z. H. Cheng, D. X. Shi
and H.-J. Gao, Structural Properties of Tetra-tert-butyl Zinc(II)
Phthalocyanine Isomers on a Au(111) Surface, J. Phys. Chem.
C, 2009, 113, 11223–11227, DOI: 10.1021/jp901193h.
40 V. N. Nemykin and E. A. Lukyanets, Synthesis of substituted
phthalocyanines, Arkivoc, 2010, 2010, 136, DOI: 10.3998/
ark.5550190.0011.104.
41 A. Singha, R. Baltic, F. Donati, C. Wa¨ckerlin, J. Dreiser,
L. Persichetti, S. Stepanow, P. Gambardella, S. Rusponi
and H. Brune, 4f occupancy and magnetism of rare-earth
atoms adsorbed on metal substrates, Phys. Rev. B, 2017, 96,
224418, DOI: 10.1103/PhysRevB.96.224418.
42 C. Piamonteze, U. Flechsig, S. Rusponi, J. Dreiser, J. Heidler,
M. Schmidt, R. Wetter, M. Calvi, T. Schmidt, H. Pruchova,
J. Krempasky, C. Quitmann, H. Brune and F. Nolting, X-
Treme beamline at SLS: X-ray magnetic circular and linear
dichroism at high eld and low temperature, J. Synchrotron
Radiat., 2012, 19, 661, DOI: 10.1107/S0909049512027847.
43 L. Floreano, A. Cossaro, R. Gotter, A. Verdini, G. Bavdek,
F. Evangelista, A. Ruocco, A. Morgante and D. Cvetko, Periodic
Arrays of Cu-Phthalocyanine Chains on Au(110), J. Phys. Chem.
C, 2008, 112, 10794–10802, DOI: 10.1021/jp711140e.
44 G. Di Santo, C. Castellarin-Cudia, M. Fanetti, B. Taleatu,
P. Borghetti, L. Sangaletti, L. Floreano, E. Magnano,
F. Bondino and A. Goldoni, Conformational Adaptation
and Electronic Structure of 2H-Tetraphenylporphyrin on
Ag(111) during Fe Metalation, J. Phys. Chem. C, 2011, 115,
4155–4162, DOI: 10.1021/jp111151n.
45 A. Thompson, D. Attwood, E. Gullikson, M. Howells,
K.-J. Kim, J. Kirz, J. Kortright, I. Lindau, Y. Liu, P. Pianetta,
A. Robinson, J. Scoeld, J. Underwood and G. Wiliams, X-
ray data booklet, Lawrence Berkeley National Laboratory,
University of California, 3rd edn, 2009.
46 K. Eguchi, T. Nakagawa, Y. Takagi and T. Yokoyama, Direct
Synthesis of Vanadium Phthalocyanine and Its Electronic
and Magnetic States in Monolayers and Multilayers on
Ag(111), J. Phys. Chem. C, 2015, 119, 9805–9815, DOI:
10.1021/jp512935v.
47 L. Ottaviano, L. Lozzi, F. Ramondo, P. Picozzia and
S. Santucci, Copper hexadecauoro phthalocyanine and
naphthalocyanine: The role of shake up excitations in the
interpretation and electronic distinction of high-resolution
X-ray photoelectron spectroscopy measurements, J. Electron
Spectrosc. Relat. Phenom., 1999, 105, 145–154, DOI:
10.1016/S0368-2048(99)00064-X.
48 R. Gaisch, J. K. Gimzewski, B. Reihl, R. R. Schlittler,
M. Tschudy and W. D. Schneider, Low-temperature ultra-
high-vacuum scanning tunneling microscope,
Ultramicroscopy, 1992, 1621, 42–44, DOI: 10.1016/0304-
3991(92)90495-6.RSC Adv., 2019, 9, 34421–34429 | 34429