Substrate-mediated effects in photothermal patterning of alkanethiol self-assembled monolayers with microfocused continuous-wave lasers

• Anja Schröter,
• Mark Kalus and
• Nils Hartmann

Beilstein J. Nanotechnol. 2012, 3, 65–74, doi:10.3762/bjnano.3.8

• continuous-wave lasers. The lateral resolution, generally, depends on both the type of the organic monolayer and the nature of the substrate. In previous studies we reported on photothermal patterning of distinct types of SAMs on Si supports. In this contribution, a systematic study on the impact of the

• patterning technique. Because of the strongly temperature-dependent thermal conductivity of Si, surface-temperature profiles on Au/Si substrates are very narrow ensuring a particularly high lateral resolution. At a 1/e spot diameter of 2 µm, fabrication of subwavelength structures with diameters of 300–400

• optical diffraction limit, laser nanofabrication encounters significant challenges. Typically, minimum structure sizes are not much smaller than the wavelength of the laser source [13]. A means to extend the lateral resolution of laser patterning techniques into the subwavelength range is to take

Distinction of nucleobases – a tip-enhanced Raman approach

• Regina Treffer,
• Xiumei Lin,
• Elena Bailo,
• Tanja Deckert-Gaudig and
• Volker Deckert

Beilstein J. Nanotechnol. 2011, 2, 628–637, doi:10.3762/bjnano.2.66

• of labeling or amplification steps. Here we investigate the intrinsic properties of tip-enhanced Raman scattering (TERS) towards the development of a novel, label-free, direct sequencing method. It is known that TERS allows the acquisition of spectral information with high lateral resolution and

• electromagnetic field in the vicinity of the particle and consequently an increase of the Raman signal. Due to the size of the particle a lateral resolution of <20 nm can be reached [4][5][6][7][8]. The feasibility of TERS for biological samples has been exemplified by studies of specific molecules [9], single

• contamination. The spectra look remarkably similar and the main spectral features of uracil can be assigned. Minor variations in band intensity ratios and positions can be attributed to the previously discussed effects that appear when measuring with such a high lateral resolution [30]. Surprisingly, the

Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

• Miriam Jaafar,
• Oscar Iglesias-Freire,
• Luis Serrano-Ramón,
• Manuel Ricardo Ibarra,
• Jose Maria de Teresa and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2011, 2, 552–560, doi:10.3762/bjnano.2.59

• different short, medium and long range interactions with high sensitivity and lateral resolution. The spreading of this technique was possible thanks to the development of specific operation modes and to the functionalization of the probes. Thus, regarding the mode employed, SFM can be used to characterize

• recorded at a given distance from the surface using the so-called lift mode [31] or retrace mode [32]. Typical distances for this second scan are between 20 nm and 50 nm. However, in order to improve both the lateral resolution and sensitivity, especially when dealing with materials with weak magnetization

Tip-enhanced Raman spectroscopic imaging of patterned thiol monolayers

• Johannes Stadler,
• Thomas Schmid,
• Lothar Opilik,
• Phillip Kuhn,
• Petra S. Dittrich and
• Renato Zenobi

Beilstein J. Nanotechnol. 2011, 2, 509–515, doi:10.3762/bjnano.2.55

• the lateral resolution of TERS was not used to its full potential, but, by exploiting the signal enhancement, weak scatterers could be identified over a larger area. Thiols are used for several purposes. They can form a very thin protective layer on metal surfaces [8] or can be employed in sensorics

• ]. Single point TERS experiments have already been presented by our group in a study of the spectral and binding properties of 4-PySH on gold [29]. By using TERS, the topography and the chemical composition of molecular monolayers can be measured simultaneously during Raman imaging with high lateral

• resolution, around 15 nm, as demonstrated for areas of less than 500 × 500 nm2 [30]. As shown here, large sample areas can also be measured to gain information from coarser structures. Traditionally this is the scale where confocal Raman microscopy has its strengths, but due to the low signal intensity from

The role of the cantilever in Kelvin probe force microscopy measurements

• George Elias,
• Thilo Glatzel,
• Ernst Meyer,
• Alex Schwarzman,
• Amir Boag and
• Yossi Rosenwaks

Beilstein J. Nanotechnol. 2011, 2, 252–260, doi:10.3762/bjnano.2.29

• obtain high lateral resolution. Colchero et al. [12] calculated the influence of the cantilever on the KPFM resolution, and several groups [13][14][15] derived analytic expressions for the cantilever electrostatic force. To the best of our knowledge, despite the above studies, the accurate role of the

• of relative to a model that takes into account only the tip. In addition, since only a scaling factor is introduced in Equation 2, the cantilever does not affect the lateral resolution, but may strongly affect the CPD absolute value, even in high resolution UHV KPFM measurements, as we demonstrate

• below. It should be noted that our model does not include signal-to-noise considerations, which may reduce the lateral resolution due to the above scaling. Results and Discussion Cantilever influence on the system PSF and force analysis The influence of the cantilever was calculated for two different

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• . This means on the other hand, the contact potential difference is actually 2 to 10 times larger than recorded. Furthermore, we conclude that the tip is influenced by these defects over a distance of approximately 2–3 nm, which might be a reasonable estimation of the tip size. This gives also the lateral

• resolution of the measurements. As shown in [36] and [49], the determined contact potential difference depends also on the tip-sample distance. In general, a smaller distance increases the size of the interaction and decreases the integration area, this means the determined difference of the contact

Magnetic interactions between nanoparticles

• Steen Mørup,
• Mikkel Fougt Hansen and
• Cathrine Frandsen

Beilstein J. Nanotechnol. 2010, 1, 182–190, doi:10.3762/bjnano.1.22

• magnetic field component of a thin sample with a lateral resolution of a few nanometers [32][33]. From the obtained images, the influence of dipolar interactions between magnetic nanoparticles can be very apparent. For example, this technique has resolved an almost linear magnetic flux along the chain

Tip-sample interactions on graphite studied using the wavelet transform

• Giovanna Malegori and
• Gabriele Ferrini

Beilstein J. Nanotechnol. 2010, 1, 172–181, doi:10.3762/bjnano.1.21

• radius of curvature given by the manufacturer (R = 10 nm). To promote this technique from proof of principle to a measurement of the Hamaker constant with a good lateral resolution, a thorough characterization of the tip radius of curvature is needed. Finally, we note that the whole force curve is

Preparation, properties and applications of magnetic nanoparticles

• Ulf Wiedwald and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 21–23, doi:10.3762/bjnano.1.4

• small statistical significance like in case of High Resolution Transmission Electron Microscopy (HR-TEM) and Spin Polarized Scanning Tunneling Microscopy (SP-STM) or the necessary lateral resolution is only on the verge of being approached as in case of synchrotron-based microscopy methods like