Cytotoxicity of doxorubicin-conjugated poly[N-(2-hydroxypropyl)methacrylamide]-modified γ-Fe₂O₃ nanoparticles towards human tumor cells

• Zdeněk Plichta,
• Yulia Kozak,
• Rostyslav Panchuk,
• Viktoria Sokolova,
• Matthias Epple,
• Lesya Kobylinska,
• Pavla Jendelová and
• Daniel Horák

Beilstein J. Nanotechnol. 2018, 9, 2533–2545, doi:10.3762/bjnano.9.236

• induction of apoptosis [2][3]. However, its main shortcomings include dose-dependent cardio-, myelo-, and nephrotoxicity [4]. Moreover, Dox quickly disappears after intravenous administration from blood and concentrates in liver, kidneys, myocardium, spleen and lungs even if these organs are not the target

• normalized to blank controls, containing the equivalent volume of culture medium. Cytotoxicity was expressed as IC50 value calculated from full dose-response curves as drug concentration inducing 50% reduction in cell survival compared to the control cultured in parallel without the particles. The uptake

• , internalization of PHPMA-modified γ-Fe2O3 particles by the cells was restricted and the particles were localized mostly on the cell surface and in the perimembranous space, where Dox retained its activity. To get comparable dose-dependent data, the amount of Dox in P(HPMA-MMAA)-Dox added to the γ-Fe2O3@PHPMA

Phosphorus monolayer doping (MLD) of silicon on insulator (SOI) substrates

• Noel Kennedy,
• Ray Duffy,
• Luke Eaton,
• Dan O’Connell,
• Scott Monaghan,
• Shane Garvey,
• James Connolly,
• Chris Hatem,
• Justin D. Holmes and
• Brenda Long

Beilstein J. Nanotechnol. 2018, 9, 2106–2113, doi:10.3762/bjnano.9.199

• comprehensive data set available in Table S1 (Supporting Information File 1). The sheet carrier concentration (CC, dose) values, from ac mode, are virtually the same for both the 13 and 66 nm substrates. This is due to the overall dose available being limited by surface coverage of the ADP dopant molecule

• . Consistent dose values produced by MLD are desirable when compared with fluctuations seen using other techniques. However, the volume of the 13 nm samples is significantly less than that of the 66 nm sample, which leads to a higher carrier concentration (CC, n; concentration = dose/thickness). This is a very

• to an increased dose with maximum active carrier concentration levels remaining at 2 × 1019 cm−3. This leads us to believe that the presence of SiO2 near the sample surface may be inhibiting the in-diffusion of the P dopant atoms. The final noteworthy aspect of this SIMS profile is the peak seen at

High-throughput synthesis of modified Fresnel zone plate arrays via ion beam lithography

• Kahraman Keskinbora,
• Umut Tunca Sanli,
• Margarita Baluktsian,
• Corinne Grévent,
• Markus Weigand and
• Gisela Schütz

Beilstein J. Nanotechnol. 2018, 9, 2049–2056, doi:10.3762/bjnano.9.194

• cases, the drift correction can be unnecessary, but the MP-E can still be desired when a better dose distribution or a well-defined wall geometry is aimed for in structures with higher aspect ratio [38]. We have shown that a much faster process can be devised by employing a single-pass-exposure (SP-E

Defect formation in multiwalled carbon nanotubes under low-energy He and Ne ion irradiation

• Santhana Eswara,
• Jean-Nicolas Audinot,
• Brahime El Adib,
• Maël Guennou,
• Tom Wirtz and
• Patrick Philipp

Beilstein J. Nanotechnol. 2018, 9, 1951–1963, doi:10.3762/bjnano.9.186

• samples and corresponding Raman spectra are shown in Figure 3. The images were acquired after He+ irradiation with a fluence of 1018 ions/cm2 (Figure 3A,B) and after Ne+ irradiation with a dose of 1017 ions/cm2 (Figure 3D,E). For both He+ and Ne+ irradiation, thin areas (Figure 3A,D) show that the

A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si_1−xGe_x and Si layers

• Richard Daubriac,
• Emmanuel Scheid,
• Hiba Rizk,
• Richard Monflier,
• Sylvain Joblot,
• Rémi Beneyton,
• Pablo Acosta Alba,
• Sébastien Kerdilès and
• Filadelfo Cristiano

Beilstein J. Nanotechnol. 2018, 9, 1926–1939, doi:10.3762/bjnano.9.184

• ultrathin layers The Hall effect measurement is a well-known technique that allows one to access three important physical parameters for material characterization: the sheet resistance Rs, the active Hall dose NH and the Hall mobility µH. At first, a Van der Pauw technique is used to determine the sheet

• discontinuity throughout the two measurement runs. On the other hand, the sheet resistance RS constantly increases (while the Hall dose NH decreases) and exhibits a discontinuity between the two runs. Indeed, as the doping concentration is uniform throughout the doped layer, the associated carrier mobility is

• expected to remain invariant in the entire layer. In contrast, as the layer becomes thinner and thinner, the active Hall dose decreases and, for a fixed carrier concentration (and hence mobility), the increase of the sheet resistance is predicted by Equation 1: with Xj being the layer thickness, q the

Magnetic properties of Fe₃O₄ antidot arrays synthesized by AFIR: atomic layer deposition, focused ion beam and thermal reduction

• Juan L. Palma,
• Alejandro Pereira,
• Raquel Álvaro,
• José Miguel García-Martín and
• Juan Escrig

Beilstein J. Nanotechnol. 2018, 9, 1728–1734, doi:10.3762/bjnano.9.164

• dose of 30 mC/cm2. The dwell time was chosen to be sure that the ion beam completely perforated the Fe2O3 film and that the hole diameter was quite homogeneous, so at least 20 nm of the substrate were also etched. These antidot arrays are then placed into a furnace GSL-1100X from MTI Corporation, which

• of 40 μm diameter that allows one to isolate the magnetic signal from the rest of the magnetic film. The trench was etched using a 20 mC/cm2 ion beam dose. Moreover, for the sake of comparison, regions confined by a trench but without any pattering, i.e., Fe2O3 disks with 40 μm diameter, were also

Cathodoluminescence as a probe of the optical properties of resonant apertures in a metallic film

• Kalpana Singh,
• Evgeniy Panchenko,
• Babak Nasr,
• Amelia Liu,
• Lukas Wesemann,
• Timothy J. Davis and
• Ann Roberts

Beilstein J. Nanotechnol. 2018, 9, 1491–1500, doi:10.3762/bjnano.9.140

• different transverse parameters were milled using a helium ion microscope (Nanofab Orion, Zeiss) operating at an accelerating voltage of 30 kV and a beam current of 0.1 to 100 pA. A Fibics NPVE pattern generator was used to control the milling parameters such as dose, beam step size and dwell time. Test

• writing was performed on a 100 nm thick Au film on a borosilicate glass substrate. Initial exposures indicated a dose of 15 nC/cm2 as the optimal initial setting for the ion beam with a 1 µs dwell time and 50% beam overlap. The optimised ion beam current selected for milling was 1.5–2.4 pA, producing the

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137

• increased by increasing the photocatalyst dose [154]. Ku et al. reported that the combination of ZnO on the surface of TiO2 at a higher calcination temperature (>500 °C) prevents the transformation of anatase to rutile phase. It also enhances the specific surface area of the ZnO/TiO2 composite by inhibiting

Nanoporous silicon nitride-based membranes of controlled pore size, shape and areal density: Fabrication as well as electrophoretic and molecular filtering characterization

• Axel Seidenstücker,
• Stefan Beirle,
• Fabian Enderle,
• Paul Ziemann,
• Othmar Marti and
• Alfred Plettl

Beilstein J. Nanotechnol. 2018, 9, 1390–1398, doi:10.3762/bjnano.9.131

• allows for the optimization of the molecule-specific illumination dose. Typically, with a sampling time between 0.5 and 2 min, the total measurement time was varied from 1 to 4 h. The intensity of the fluorescent emission signal was determined by summing up the 16-bit signals of three different pixel

Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations

• Jaison Jeevanandam,
• Ahmed Barhoum,
• Yen S. Chan,
• Alain Dufresne and
• Michael K. Danquah

Beilstein J. Nanotechnol. 2018, 9, 1050–1074, doi:10.3762/bjnano.9.98

Graphene composites with dental and biomedical applicability

• Sharali Malik,
• Felicite M. Ruddock,
• Adam H. Dowling,
• Kevin Byrne,
• Wolfgang Schmitt,
• Ivan Khalakhan,
• Yoshihiro Nemoto,
• Hongxuan Guo,
• Lok Kumar Shrestha,
• Katsuhiko Ariga and
• Jonathan P. Hill

Beilstein J. Nanotechnol. 2018, 9, 801–808, doi:10.3762/bjnano.9.73

• and thought to be non-cytotoxic [9][10][11][12][13], but as toxicity depends on many factors such as size, shape, concentration and dose further studies with regard to specific applications are needed. Therefore, the aim of these experiments was to assess the use of graphene with a glass-ionomer (GI

Electron interactions with the heteronuclear carbonyl precursor H₂FeRu₃(CO)₁₃ and comparison with HFeCo₃(CO)₁₂: from fundamental gas phase and surface science studies to focused electron beam induced deposition

• Ragesh Kumar T P,
• Paul Weirich,
• Lukas Hrachowina,
• Marc Hanefeld,
• Ragnar Bjornsson,
• Helgi Rafn Hrodmarsson,
• Sven Barth,
• D. Howard Fairbrother,
• Michael Huth and
• Oddur Ingólfsson

Beilstein J. Nanotechnol. 2018, 9, 555–579, doi:10.3762/bjnano.9.53

• monitored in situ by X-ray photoelectron spectroscopy (XPS) and mass spectrometry. Figure 9 shows the evolution of the O 1s, Fe 2p and Ru 3d/C 1s XPS regions of a nanometer-thick film of H2FeRu3(CO)13 adsorbed onto a gold substrate at 213 K, plotted as a function of increasing electron dose. Area analysis

• low intensity. Upon electron irradiation, the Ru 3d3/2 and Ru 3d5/2 peak positions shift measurably towards a lower binding energy, and the CO peak decreases in intensity. Spectral fitting of the Ru 3d/C 1s XPS region measured after an electron irradiation of a dose of 1.4 × 1018 e−/cm2 reveals an

• changes as electron irradiation, but at a much slower rate. Based on the variation in the O 1s area we estimate that the time taken to acquire one XPS scan of the O 1s, Fe 2p and C 1s/Ru 3d regions corresponds to an electron dose of ≈6.3 × 1014 e−/cm2. Consequently, the effect of X-ray irradiation during

Single-step process to improve the mechanical properties of carbon nanotube yarn

• Maria Cecilia Evora,
• Xinyi Lu,
• Nitilaksha Hiremath,
• Nam-Goo Kang,
• Kunlun Hong,
• Roberto Uribe,
• Gajanan Bhat and
• Jimmy Mays

Beilstein J. Nanotechnol. 2018, 9, 545–554, doi:10.3762/bjnano.9.52

• , Acros Organics, 99+%). All chemical reagents were used as received. The irradiation process was carried out in an industrial accelerator operated by NEO Beam – Mercury Plastics, Inc – Middlefield-OH, 3.8 MeV beam energy, pulse current 38.3 mA, 27 kGy/pass with dose rate of 5 kGy/s. Sample preparation A

• a dose of 27 kGy. The low dose of 27 kGy was chosen for this preliminary investigation because only functionalization on the MWNT powder surface was desired. The aim of this preliminary study was to verify the conversion of AN to PAN on the MWNT powder surface under e-beam irradiation. An aqueous

• electronic band structure of the graphitic material. There was a decrease of the G′ peak FWHM from 117.51 cm−1 (untreated sample) to 109.51 cm−1 (treated with 80% AN and irradiated with a dose of 108 kGy) and 105 cm−1 (treated with 80% AA and irradiated with a dose of 108 kGy) (Figure 3). This happens

Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

• Nagamalai Vasimalai,
• Vânia Vilas-Boas,
• Juan Gallo,
• María de Fátima Cerqueira,
• Mario Menéndez-Miranda,
• José Manuel Costa-Fernández,
• Lorena Diéguez,
• Begoña Espiña and
• María Teresa Fernández-Argüelles

Beilstein J. Nanotechnol. 2018, 9, 530–544, doi:10.3762/bjnano.9.51

• -dots in the cancer cultures compared to the non-cancerous cells. Results showed that the spice-derived C-dots inhibited cell viability dose-dependently after a 24 h incubation period, displaying a higher toxicity in LN-229, than in HK-2 cells. As a control, C-dots synthesized from citric acid did not

• effect of the same concentration of C-dots on LN-229 cells, the cinnamon C-dots were the least toxic. For instance, at a dose of 2 mg·mL−1 cinnamon C-dots induced around 35% reduction in cell viability, followed by both red chilli and turmeric C-dots, which induced nearly 50% reduction in cell viability

Gas-assisted silver deposition with a focused electron beam

• Luisa Berger,
• Katarzyna Madajska,
• Iwona B. Szymanska,
• Katja Höflich,
• Mikhail N. Polyakov,
• Jakub Jurczyk,
• Carlos Guerra-Nuñez and
• Ivo Utke

Beilstein J. Nanotechnol. 2018, 9, 224–232, doi:10.3762/bjnano.9.24

• , silver crystal growth presents a strong dependency on electron dose and precursor refreshment. Keywords: focused electron beam induced deposition; low volatility precursor; silver; Introduction The fabrication of defined patterns in the nanometer regime demands techniques with high lateral resolution

• irradiates it again, thus the FEBID can continue with fresh adsorbates and less co-deposition of carbon. For further studies, box deposits were written with the same electron dose of 7.44 nC/µm2 but different dwell and refreshment times. On first sight it is visible that for short refreshment times as in

• evidence that the crystals seen in the scanning electron micrographs (Figure 1) are made of silver. Figure 3a depicts a line written on a carbon membrane of a TEM grid in our SEM with 25 kV and 0.5 nA and an electron dose of 0.79 pC/µm. Figure 3b displays a bright field scanning transmission electron

Comparative study of post-growth annealing of Cu(hfac)₂, Co₂(CO)₈ and Me₂Au(acac) metal precursors deposited by FEBID

• Marcos V. Puydinger dos Santos,
• Aleksandra Szkudlarek,
• Artur Rydosz,
• Carlos Guerra-Nuñez,
• Fanny Béron,
• Kleber R. Pirota,
• Stanislav Moshkalev,
• José Alexandre Diniz and
• Ivo Utke

Beilstein J. Nanotechnol. 2018, 9, 91–101, doi:10.3762/bjnano.9.11

• here we studied 50 nm thick thin films while the previous material was much thicker and received a higher dose during post-growth irradiation of the already deposited underlying material. The same mechanism could also be responsible for the lower copper content found in the present study. Raman

Response under low-energy electron irradiation of a thin film of a potential copper precursor for focused electron beam induced deposition (FEBID)

• Leo Sala,
• Iwona B. Szymańska,
• Céline Dablemont,
• Anne Lafosse and
• Lionel Amiaud

Beilstein J. Nanotechnol. 2018, 9, 57–65, doi:10.3762/bjnano.9.8

• for 210 min. Regular off-beam measurements are taken to remove the background contribution from the desorption signal. The evolution with the cumulated dose of the CF3 signal, normalized to transmitted current, is plotted in Figure 4. The signal is decreasing with time as the available quantities on

• corresponding colour. Evolution of CF3 neutral fragment detection with the cumulated dose (fluence) under irradiation at 1.5 eV. Squares: measurement, line: adjusted model. HREELS vibrational signature attributions. Acknowledgements This work was conducted within the framework of the COST action CM1301 (CELINA

Hyperthermic intracavitary nanoaerosol therapy (HINAT) as an improved approach for pressurised intraperitoneal aerosol chemotherapy (PIPAC): Technical description, experimental validation and first proof of concept

• Daniel Göhler,
• Stephan Große,
• Alexander Bellendorf,
• Thomas Albert Falkenstein,
• Mehdi Ouaissi,
• Jürgen Zieren,
• Michael Stintz and
• Urs Giger-Pabst

Beilstein J. Nanotechnol. 2017, 8, 2729–2740, doi:10.3762/bjnano.8.272

• 1.4 bar that led to an effective dose of the 99mTc pertechnetate-containing solution of 0.28 mL. PIPAC-MIP was performed at a volumetric flow rate of 30 mL/min for 5 min that led to a dose of 150 mL. Short after 99mTc pertechnetate exposure, scintigraphic analyses (i.e., planar scintigraphy as well as

• projections with a resolution of 128 × 128 px were recorded with an acquisition time of 8 s per projection. Anterior (i.e., LDR = left–dorsal–right) as well posterior (i.e., RVL = right–ventral–left) planar images were acquired with an acquisition time of 3 min per position. Finally, a low-dose computer

• doxorubicin dose of 0.88 mL (i.e., 1.76 mg doxorubicin hydrochloride). PIPAC-MIP was performed with diluted doxorubicin (1 mL doxorubicin in 50 mL aqueous 0.9 wt % sodium chloride solution) at a volumetric flow rate of 30 mL/min for 100 s that led to an effective doxorubicin dose of 2.9 mL (i.e., 5.8 mg

Localized growth of carbon nanotubes via lithographic fabrication of metallic deposits

• Fan Tu,
• Martin Drost,
• Imre Szenti,
• Janos Kiss,
• Zoltan Kónya and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2017, 8, 2592–2605, doi:10.3762/bjnano.8.260

• contain high amounts of carbon as contamination. For example, Sharma et al. [20] presented the possibility to control the deposited particle size by varying the EBID parameters (i.e., electron dose and beam current) but no further CNTs were shown to grow on these as-deposited Fe-containing nanoparticles

• catalysts to synthesize well-defined CNTs with controllable morphology via CVD. The influence of the chemical composition and, in particular, of the fabrication parameters (i.e., electron dose and AG time) of Fe deposits were investigated with respect to their suitability and properties as seeds for

• subsequent AG (≈60 min autocatalytic growth time) in our UHV instrument. Here, the EBID process was performed as a point irradiation, that is, the electron beam rests at a fixed position for a certain amount of time and thus provides a controlled local electron dose. The enlargement of the deposits with

Amplified cross-linking efficiency of self-assembled monolayers through targeted dissociative electron attachment for the production of carbon nanomembranes

• Sascha Koch,
• Christopher D. Kaiser,
• Paul Penner,
• Michael Barclay,
• Lena Frommeyer,
• Daniel Emmrich,
• Patrick Stohmann,
• Tarek Abu-Husein,
• Andreas Terfort,
• D. Howard Fairbrother,
• Oddur Ingólfsson and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2017, 8, 2562–2571, doi:10.3762/bjnano.8.256

• spectroscopy (XPS), to determine whether the high relative DEA cross section for iodide loss from 2-I-BPT as compared to 2-Br-BP and 2-Cl-BP is reflected in the cross-linking efficiency of SAMs made from these materials. Such sensitization could reduce the electron dose needed for the cross-linking process and

• ) verified the existence of a mechanically stable CNM created from 2-I-BPT after exposure to an electron dose as low as 1.8 mC/cm2. In contrast, SAMs made from BPT, 2-Cl-BPT and 2-Br-BPT did not form stable CNMs after a significantly higher electron dose of 9 mC/cm2. Keywords: 2D materials; carbon

• determination of the required dose for the respective CNM formation also by directly testing the mechanical strength and microscope images of the cross-linked SAMs. Figure 2a shows the XP spectra of the respective halogen atoms of 2-Cl-BPT, 2-Br-BPT and 2-I-BPT, recorded for nine different stages of irradiation

Direct writing of gold nanostructures with an electron beam: On the way to pure nanostructures by combining optimized deposition with oxygen-plasma treatment

• Domagoj Belić,
• Mostafa M. Shawrav,
• Emmerich Bertagnolli and
• Heinz D. Wanzenboeck

Beilstein J. Nanotechnol. 2017, 8, 2530–2543, doi:10.3762/bjnano.8.253

• atom %, depending on the sustained electron beam dose. As a second step, oxygen-plasma treatment is established to further enhance the Au content in the structures, while preserving their morphology to a high degree. This two-step process represents a simple, feasible and high-throughput method for

• samples were produced using the same HT and I values, the electron dose that the material sustained during deposition was approximately two times higher in the case of planar structure (2.3 × 10−7 C·μm−2 vs ≈1 × 10-7 C·μm−2). It was the first clear evidence that a change of electron beam parameters could

• , the full experimental parameter space of a typical FEBID system is multidimensional – it encompasses electron beam parameters (such as acceleration voltage, i.e., high tension, electron beam current, electron dose, i.e., deposition time), precursor parameters (such as precursor type, flux, and

Comparing postdeposition reactions of electrons and radicals with Pt nanostructures created by focused electron beam induced deposition

• Julie A. Spencer,
• Michael Barclay,
• Miranda J. Gallagher,
• Robert Winkler,
• Ilyas Unlu,
• Yung-Chien Wu,
• Harald Plank,
• Lisa McElwee-White and
• D. Howard Fairbrother

Beilstein J. Nanotechnol. 2017, 8, 2410–2424, doi:10.3762/bjnano.8.240

• ) and was invariant to further increases in electron dose. In related studies, EDS of PtCl2 deposits exposed to 20 h of electron irradiation in the AES revealed only a small decrease (≈5%) in the Cl EDS signal (see Figure 1d). Similarly, electron beam irradiation of PtCl2 deposits in the SEM for 2 h at

• , under precursor limited deposition conditions. In such a scenario, each PtCl2 moiety deposited at the surface of the growing nanostructure could be exposed to a sufficiently large electron dose to effect Cl loss. Atomic hydrogen (AH) As shown in Figures 2–5, exposure of PtCl2 deposits to AH using the

Involvement of two uptake mechanisms of gold and iron oxide nanoparticles in a co-exposure scenario using mouse macrophages

• Dimitri Vanhecke,
• Dagmar A. Kuhn,
• Dorleta Jimenez de Aberasturi,
• Sandor Balog,
• Ana Milosevic,
• Dominic Urban,
• Diana Peckys,
• Niels de Jonge,
• Wolfgang J. Parak,
• Alke Petri-Fink and
• Barbara Rothen-Rutishauser

Beilstein J. Nanotechnol. 2017, 8, 2396–2409, doi:10.3762/bjnano.8.239

• monitored by dynamic light scattering and the dose deposited onto the cell surface was determined by a modelling approach. The murine macrophage cell line J774A.1 was then used to study uptake and intracellular fate by means of laser scanning microscopy (LSM), environmental scanning electron microscopy

• characterization. Given that the particles were polydisperse and were functionalized with a polymer, the dose delivered near the cell was estimated by approaches reported elsewhere, taking into account the geometrical parameters of the cell culture wells, such as overall fluid volume and well diameter [28][29

• NPs adhere to it, and the delivered dose is expressed as the fraction of the administered dose (Figure 1). AuNPs deposited faster than FeOxNPs, and hence a higher fraction of AuNPs was in contact with the cells throughout the experiment. After 5 min, more than 5% of the administered dose arrived at

Bi-layer sandwich film for antibacterial catheters

• Gerhard Franz,
• Florian Schamberger,
• Hamideh Heidari Zare,
• Sara Felicitas Bröskamp and
• Dieter Jocham

Beilstein J. Nanotechnol. 2017, 8, 1982–2001, doi:10.3762/bjnano.8.199

• drug. However, its toxic behavior is also well known. Unfortunately, systematic investigations referring to toxicity and long-term exposition are rare. In 1996, the U.S. Environmental Protection Agency (EPA) published values for the long-term oral reference dose (RfD) [20][21]. These values are based

Application of visible-light photosensitization to form alkyl-radical-derived thin films on gold

• Rashanique D. Quarels,
• Xianglin Zhai,
• Neepa Kuruppu,
• Jenny K. Hedlund,
• Ashley A. Ellsworth,
• Amy V. Walker,
• Jayne C. Garno and
• Justin R. Ragains

Beilstein J. Nanotechnol. 2017, 8, 1863–1877, doi:10.3762/bjnano.8.187

• × 10−9 mbar. The primary Bi+ ions had a kinetic energy of 25 keV, were contained within a ≈ 100 nm diameter probe beam, and were rastered over a (100 × 100) μm2 area. All spectra were obtained in the static regime using a total ion dose of less than 1010 ions·cm−2. The secondary ions were extracted