Core-level spectra and molecular deformation in adsorption: V-shaped pentacene on Al(001)

• Anu Baby,
• He Lin,
• Gian Paolo Brivio,
• Luca Floreano and
• Guido Fratesi

Beilstein J. Nanotechnol. 2015, 6, 2242–2251, doi:10.3762/bjnano.6.230

• contributions from the non-equivalent C atoms provide evidence of the molecular orbital filling, hybridization, and interchange induced by distortion. The alteration of the C–C bond lengths due to the V-shaped bending decreases by a factor of two the azimuthal dichroism of NEXAFS spectra, i.e., the energy

• of about 13° with the surface plane. Looking at the main σ* peak centered at around 294 eV, we observe a small energy splitting between transitions with the electric field along the long and short molecular axes. This phenomenon called the azimuthal dichroism is much reduced, as compared to that of

• lengths along the two directions are more similar, as we reported in Table 1. Still the molecule being inherently anisotropic determines the residual azimuthal dichroism reduced to approx. 1 eV. Reporting the initial state contributions in this energy range, the x-direction spectrum has largest

DNA–melamine hybrid molecules: from self-assembly to nanostructures

• Rina Kumari,
• Shib Shankar Banerjee,
• Anil K. Bhowmick and
• Prolay Das

Beilstein J. Nanotechnol. 2015, 6, 1432–1438, doi:10.3762/bjnano.6.148

• double helix, Supporting Information File 1, Figure S4). The circular dichroism (CD) spectra (see Supporting Information File 1, Figure S5) showed that the B-form of the duplex is maintained in the two self-assembled DNA–melamine nanostructures. However, a decline in the intensity of both the positive

Natural and artificial binders of polyriboadenylic acid and their effect on RNA structure

• Giovanni N. Roviello,
• Domenica Musumeci,
• Valentina Roviello,
• Marina Pirtskhalava,
• Alexander Egoyan and
• Merab Mirtskhulava

Beilstein J. Nanotechnol. 2015, 6, 1338–1347, doi:10.3762/bjnano.6.138

• Yadav et al. This study took advantage of different techniques, including UV spectrophotometry, circular dichroism, spectrofluorimetry, and viscosimetry, were they were able to demonstrate a mechanism of partial intercalation for this binding [25]. The interaction process was confirmed by both

• hypochromic and bathochromic effects revealed in the UV–vis spectrum of the alkaloid. The binding also induced increases in fluorescence intensity and viscosity of the solutions and was accompanied by perturbations of the circular dichroism spectrum of the single-stranded poly(rA). From the spectrophotometric

• analysis it was shown that berberine was able to strongly bind single-stranded poly(rA) in a non-cooperative manner. On the other side, the same compound did not induce variations in the adsorption, fluorescence, and circular dichroism spectra of double-stranded poly(rA) and it did not increase the

Protein corona – from molecular adsorption to physiological complexity

• Lennart Treuel,
• Dominic Docter,
• Michael Maskos and
• Roland H. Stauber

Beilstein J. Nanotechnol. 2015, 6, 857–873, doi:10.3762/bjnano.6.88

• techniques such as fluorescence spectroscopy [76][77], Fourier transform infrared spectroscopy [78], Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) [36][79] as well as circular dichroism spectroscopy [6][47][53][80][81]. Also, other established techniques were used to study protein

• further attention. Treuel and coworkers employed circular dichroism (CD) spectroscopy to study the thermodynamic and structural aspects of NP–protein interactions [47]. They investigated the formation of a serum albumin, an established model protein [7][8][9][80][111], corona around Au (13 ± 2 nm) and Ag

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• activated process of Co diffusion into the Si layer is efficiently hindered at 220 K. Magnetic characterization of the Co nanolines using X-ray magnetic circular dichroism reveals that the first atomic Co layer directly adsorbed onto the Si nanoribbons presents a weak magnetic response. However, the second

• magnetic circular dichroism (XMCD); Introduction In the last fifteen years, bottom-up approaches have provided promising routes for creating a wide range of nanostructures with new magnetic, electronic, photonic or catalytic properties. Such approaches are based on growth phenomena after atoms and

• , Co nanolines. The first magnetic characterization results of the Co nanolines using X-ray magnetic circular dichroism (XMCD) are reported, revealing that the atomic Co layer directly adsorbed onto the Si nanoribbons presents a weak magnetic response. The second Co layer exhibits an enhanced

Self-assembled anchor layers/polysaccharide coatings on titanium surfaces: a study of functionalization and stability

• Ognen Pop-Georgievski,
• Dana Kubies,
• Josef Zemek,
• Neda Neykova,
• Roman Demianchuk,
• Eliška Mázl Chánová,
• Miroslav Šlouf,
• Milan Houska and
• František Rypáček

Beilstein J. Nanotechnol. 2015, 6, 617–631, doi:10.3762/bjnano.6.63

• birefringence and dichroism causing errors in the ellipsometric angles Δ and Ψ smaller than 0.3° and 0.1°, respectively. These errors were corrected following the method of Azzam and Bashara [61]. To increase the measurement precision and exclude errors from the variations of layer thickness throughout the

Overview of nanoscale NEXAFS performed with soft X-ray microscopes

• Peter Guttmann and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2015, 6, 595–604, doi:10.3762/bjnano.6.61

• drawback of this technique is that it cannot handle samples which are thicker than a few atomic diameters [15][16][17]. By using linear polarized X-rays available at synchrotron radiation sources effects by dichroism in materials can be studied. Thus, in this case, the degree of alignment, molecular

• orientation as well as spectral assignments can be determined [9][18][19][20]. Such measurements of the polarization dependence (linear dichroism) relative to a characteristic direction of isotropic samples using the momentum transfer directional dependence in an electron microscope is possible, but highly

UHV deposition and characterization of a mononuclear iron(III) β-diketonate complex on Au(111)

• Irene Cimatti,
• Silviya Ninova,
• Valeria Lanzilotto,
• Luigi Malavolti,
• Luca Rigamonti,
• Brunetto Cortigiani,
• Matteo Mannini,
• Elena Magnano,
• Federica Bondino,
• Federico Totti,
• Andrea Cornia and
• Roberta Sessoli

Beilstein J. Nanotechnol. 2014, 5, 2139–2148, doi:10.3762/bjnano.5.223

• fragmentation of Fe(dpm)3 upon adsorption on the Au(111) surface. Structural features with intact molecules were only observed for the saturation coverage. An ex situ prepared thick film of the complex was also investigated by X-ray magnetic circular dichroism (XMCD) and features typical of high-spin iron(III

PVP-coated, negatively charged silver nanoparticles: A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

• Sebastian Ahlberg,
• Alexandra Antonopulos,
• Jörg Diendorf,
• Ralf Dringen,
• Matthias Epple,
• Rebekka Flöck,
• Wolfgang Goedecke,
• Christina Graf,
• Nadine Haberl,
• Jens Helmlinger,
• Fabian Herzog,
• Frederike Heuer,
• Stephanie Hirn,
• Christian Johannes,
• Stefanie Kittler,
• Manfred Köller,
• Katrin Korn,
• Wolfgang G. Kreyling,
• Fritz Krombach,
• Jürgen Lademann,
• Kateryna Loza,
• Eva M. Luther,
• Marcelina Malissek,
• Martina C. Meinke,
• Daniel Nordmeyer,
• Anne Pailliart,
• Jörg Raabe,
• Fiorenza Rancan,
• Barbara Rothen-Rutishauser,
• Eckart Rühl,
• Carsten Schleh,
• Andreas Seibel,
• Christina Sengstock,
• Lennart Treuel,
• Annika Vogt,
• Katrin Weber and
• Reinhard Zellner

Beilstein J. Nanotechnol. 2014, 5, 1944–1965, doi:10.3762/bjnano.5.205

• dichroism (CD) spectroscopy in a quantitative approach allowing for the determination of equilibrium constants or binding affinities (transition midpoints) [55][59][63]. Circular dichroism signals of proteins arise from electronic transitions in specific secondary structural elements (e.g., α-helix or

Cathode lens spectromicroscopy: methodology and applications

• T. O. Menteş,
• G. Zamborlini,
• A. Sala and
• A. Locatelli

Beilstein J. Nanotechnol. 2014, 5, 1873–1886, doi:10.3762/bjnano.5.198

• and combine chemical characterization with X-ray magnetic circular dichroism–photoemission electron microscopy (XMCD–PEEM) magnetic imaging by using the variable photon polarization and energy available at the synchrotron source. Keywords: gold (Au); graphene; intercalation; low-energy electron

• microscopy (LEEM); magnetism; nanostructures; X-ray magnetic circular dichroism (XMCD); X-ray photoemission electron microscopy (XPEEM); Introduction The cathode lens, or immersion objective lens, is used to image electrons emitted from surfaces [1]. In a microscope that uses this type of objective, the

• magnetic circular and linear dichroism techniques applied to magnetic surfaces constitute major branches of XPEEM research at synchrotrons. Aside from the photon energy, undulator sources provide also the possibility to manipulate the X-ray polarization. The scattering of circularly polarized X-rays is

Hole-mask colloidal nanolithography combined with tilted-angle-rotation evaporation: A versatile method for fabrication of low-cost and large-area complex plasmonic nanostructures and metamaterials

• Jun Zhao,
• Bettina Frank,
• Frank Neubrech,
• Chunjie Zhang,
• Paul V. Braun and
• Harald Giessen

Beilstein J. Nanotechnol. 2014, 5, 577–586, doi:10.3762/bjnano.5.68

• . The upper layer disks are slightly smaller due to the clogging effect. In order to study the chiral optical properties of this pattern, we introduce at first circular dichroism (CD). Circular dichroism is defined as the difference in absorbance for right- and left-handed circularly polarized light

CoPc and CoPcF₁₆ on gold: Site-specific charge-transfer processes

• Fotini Petraki,
• Heiko Peisert,
• Johannes Uihlein,
• Umut Aygül and
• Thomas Chassé

Beilstein J. Nanotechnol. 2014, 5, 524–531, doi:10.3762/bjnano.5.61

• linear dichroism of F K-edge XAS spectra compared to N or C K-edge spectra [30]. The presence of angular dependent π* and σ* transitions indicates that fluorine atoms participate in the conjugated π system. Comparing spectra from the thick film in Figure 5a to spectra at a lower coverage of about 0.8 nm

Exploring the complex mechanical properties of xanthan scaffolds by AFM-based force spectroscopy

• Hao Liang,
• Guanghong Zeng,
• Yinli Li,
• Shuai Zhang,
• Huiling Zhao,
• Lijun Guo,
• Bo Liu and
• Mingdong Dong

Beilstein J. Nanotechnol. 2014, 5, 365–373, doi:10.3762/bjnano.5.42

• cell incubation [2] and the repair of damaged tissue [3]. Xanthan, a polysaccharide which can self-associate into a scaffold structure [4][5], has been widely used in various fields, such as food additives [6] and drug delivery [7][8]. A number of tools, including NMR [9][10], circular dichroism (CD

Antiferromagnetic coupling of TbPc₂ molecules to ultrathin Ni and Co films

• David Klar,
• Svetlana Klyatskaya,
• Andrea Candini,
• Bernhard Krumme,
• Kurt Kummer,
• Philippe Ohresser,
• Valdis Corradini,
• Valentina de Renzi,
• Roberto Biagi,
• Loic Joly,
• Jean-Paul Kappler,
• Umberto del Pennino,
• Marco Affronte,
• Heiko Wende and
• Mario Ruben

Beilstein J. Nanotechnol. 2013, 4, 320–324, doi:10.3762/bjnano.4.36

• , CNRS UMP 7504, 23 Rue du Loess, 67034 Strasbourg Cedex 2, France 10.3762/bjnano.4.36 Abstract The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni

• demonstrate that it is possible to block this relaxation and conserve the magnetization without any external field by coupling the molecules to a ferromagnetic substrate. By X-ray absorption spectroscopy and X-ray magnetic circular dichroism we study the electronic and magnetic properties of a submonolayer

• corresponding circular or linear dichroism at the Tb M4,5 absorption edges of TbPc2 on Cu(100). The XMCD signal has the shape typical for a Tb3+ ion, in agreement with what has been already reported for this molecule [20][21][24][25]. The high XMCD intensity at the M5 edge and the low intensity at the M4 edge

Physics, chemistry and biology of functional nanostructures

• Paul Ziemann and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2012, 3, 843–845, doi:10.3762/bjnano.3.94

• facilities has made an important contribution, now providing beams with spot sizes even below 10 nm, thus promising the application of spectroscopies such as photoelectron emission microscopy (PEEM) or X-ray magnetic circular dichroism (XMCD) on a single nanoobject [6][7]. Progress in the theoretical

X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge

• Carla Bittencourt,
• Adam P. Hitchock,
• Xiaoxing Ke,
• Gustaaf Van Tendeloo,
• Chris P. Ewels and
• Peter Guttmann

Beilstein J. Nanotechnol. 2012, 3, 345–350, doi:10.3762/bjnano.3.39

• unoccupied density of states, although the energies and intensities are modified by core–hole interactions [15]. When linearly polarized X-rays are used the carbon K-edge of graphene materials exhibits a strong linear dichroism, which can be used to probe local anisotropy and structural order [16]. When

• combined with X-ray microscopy, NEXAFS can be used to study isolated, free-standing nanostructures [17][18]. Linear dichroism can be used to filter the signal according to selection rules based on the symmetry of the sample electronic states and orientation with respect to the polarisation of the E-vector

• the CCD camera (Figure 1) [19]. Polarization (linear dichroism) studies are performed by rotating the sample relative to the orientation of the fixed polarization vector of the incident photons. Results and Discussion We examined several different flakes to ensure that we had selected a typical

X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

• Hicham Hamoudi,
• Ping Kao,
• Alexei Nefedov,
• David L. Allara and
• Michael Zharnikov

Beilstein J. Nanotechnol. 2012, 3, 12–24, doi:10.3762/bjnano.3.2

• dependence of the transition-matrix elements for resonant excitations [53], the average orientation of the film constituents can be derived from the NEXAFS experiment. A fingerprint of such an orientation is the linear dichroism (see Experimental section), which, among other means, can be efficiently

• the target films. Both C and N K-edge spectra of the target SAMs exhibit significant linear dichroism as follows from the differences between the spectra acquired at normal and gracing (20°) incidence of the primary X-ray beam shown in Figure 3b and Figure 5b. The difference peaks related to the π

• respective values are given in Table 1; they are close to each other for all target SAMs, independent of the chain length. Note that this result is somewhat in contrast to the C K-edge spectra in Figure 3, which exhibit an increasing linear dichroism with increasing length of the molecular chain in NC-OPEn

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• alloy formation by X-ray absorption spectroscopy and SQUID magnetometry. The excellent sensitivity of SQUID magnetometers can be exploited, at suitably selected temperatures, to detect the magnetic response corresponding to the Co particles and nanoscale alloys. X-ray magnetic circular dichroism (XMCD

• XAS energy scans, obtained in applied fields of µ0H = ± 1 T, sufficient to achieve magnetic saturation. While the Co L3,2 resonances as well as the magnetic dichroism are clearly visible, we note that even the resonant Co signal amounts to only a fraction (≈1%) of the strong TEY background (≈170 pA

Extended X-ray absorption fine structure of bimetallic nanoparticles

• Carolin Antoniak

Beilstein J. Nanotechnol. 2011, 2, 237–251, doi:10.3762/bjnano.2.28

• transition matrix elements in the E1 approximation (Equation 3) already suggests that some kinds of dichroism may exist, i.e., polarisation dependent absorption. In fact there are several types of X-ray dichroism such as X-ray natural linear dichroism (XNLD) [21][22] and natural circular dichroism (XNCD) [23

• ], X-ray magnetic linear dichroism (XMLD) [24][25], X-ray magnetic circular dichroism (XMCD) [26][27], and the more exotic X-ray non-reciprocal linear dichroism [28] and magnetochiral dichroism (XMχD) [29]. In a microscopic picture, this dependence of the absorption on the polarisation of incident X

• -rays is caused by an anisotropy of the charge (or spin) distribution, either by bonding that yields natural dichroism or by magnetic ordering that yields magnetic dichroism. A general formulation of linear and circular dichroism was given by Carra and Altarelli [30] and an overview of the different

Structural and magnetic properties of ternary Fe_1–xMn_xPt nanoalloys from first principles

• Markus E. Gruner and
• Peter Entel

Beilstein J. Nanotechnol. 2011, 2, 162–172, doi:10.3762/bjnano.2.20

• film setup. Using a vibrating sample magnetometer for saturation magnetization and hysteresis loop and X-ray magnetic circular dichroism (XMCD) to obtain the element resolved orientation of the moments, the authors observed a linear decrease of the average magnetization with increasing Mn-content

Structure, morphology, and magnetic properties of Fe nanoparticles deposited onto single-crystalline surfaces

• Armin Kleibert,
• Wolfgang Rosellen,
• Mathias Getzlaff and
• Joachim Bansmann

Beilstein J. Nanotechnol. 2011, 2, 47–56, doi:10.3762/bjnano.2.6

• combined approach of X-ray magnetic circular dichroism (XMCD), reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM) to shed light on the complex and size-dependent relation between magnetic properties, crystallographic structure, orientation and morphology. In

• scaled by a factor of 50. The low magnitude of the Fe signal relative to that of the Ni spectra reflects a well diluted deposit with about 200 particles per μm2 on the surface [38]. At this density, interactions between the particles can be neglected. Figure 2c and Figure 2d show magnetic dichroism

Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism

• Olivier Margeat,
• Marc Respaud,
• Catherine Amiens,
• Pierre Lecante and
• Bruno Chaudret

Beilstein J. Nanotechnol. 2010, 1, 108–118, doi:10.3762/bjnano.1.13

• α-Fe NPs with diameters down to 2 nm show an enhancement of the hyperfine field BHyp, indicative of enhanced µFe [10][11][12]. Recent careful measurements, by X-ray magnetic circular dichroism (XMCD) [13][14][15][16], consistently indicate an increase in the ratio of the orbital magnetic moment over

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5

• magnetic circular dichroism (XMCD) which provides information on (i) the chemical state of sample, (ii) element-specific magnetic moments and (iii) element-specific hysteresis loops. The results presented below were measured at beamline PM-3 of the BESSY II synchrotron facility in Berlin, Germany. The