R. Lohmus

Force interactions and adhesion of gold contacts using a combined atomic force microscope and transmission electron microscope

Force interactions and adhesion of gold contacts using a combined atomic force microscope and transmission electron microscope

Preparation of smooth siloxane surfaces for AFM visualization of immobilized biomolecules

Development of scanning probe microscopy (SPM) techniques during past decade has made possible to study bioprocesses at a molecular level. Common protocols for immobilization of biomolecules for SPM studies are based on their adsorption to alkylsiloxane monolayers on hydroxylated surfaces. The same procedure is also widely used for DNA chip and biosensor fabrication. For SPM studies of immobilized biomolecules smooth carrier surfaces are mandatory. Several studies refer to the lack of reproducibility in formation of smooth silanized surfaces. In this work a new method based on carrier treatment with linearly polymerized 3-aminopropyltrimethoxysilane for preparation of reproducibly smooth silanized surfaces is proposed.

Simultaneous measurement of static and kinetic friction of ZnO nanowires in situ with a scanning electron microscope.

A novel method for in situ measurement of the static and kinetic friction is developed and demonstrated for zinc oxide nanowires (NWs) on oxidised silicon wafers. The experiments are performed inside a scanning electron microscope (SEM) equipped with a nanomanipulator with an atomic force microscope tip as a probe. NWs are pushed by the tip from one end until complete displacement is achieved, while NW bending is monitored by the SEM. The elastic bending profile of a NW during the manipulation process is used to calculate the static and kinetic friction forces.

Three-dimensional subsurface imaging with laser ablation/AFM

New method for 3D nano-scale imaging was developed that combines a traditional scanning probe techniques with a local laser ablation processing of the surface of a sample. The technology opens new possibilities for ultra precise (down to atomic resolution) subsurface studies, whereas the traditional SPM sensitivity is limited to only few atomic layers. We demonstrate that our new experimental set-up can also be used for other investigations, e.g. in in situ characterization of surface processing. The approach is potentially interesting for many applications, like volume nano-imaging, in situ studies of a stimulated nano-assembling or growth, monitoring of laser processing and cleaning, etc.

Metal nanodumbbells for nanomanipulations and tribological experiments

Nanomanipulation experiments were carried out on nanodumbbells (NDs) to study their kinetic behavior and tribological properties. Ag, Au and Cu NDs were produced by laser-induced melting of corresponding nanowires (NWs). NDs were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Manipulation experiments were performed first with atomic force microscope (AFM) at ambient conditions, and then inside SEM at high vacuum conditions. Different regimes of motion were observed. In-plane and out-of-substrate-plane rotation were identified as the most preferred motion types of NDs.

Phase Transformations in Icosahedral Small Copper Particles during Their Annealing in Different Gas Media

Results from experiments on the annealing of icosahedral small particles (ISPs) of copper in different gas media are presented. The growth of nanowhisker structures and nanopores on the surfaces of ISPs is observed. The multilayer internal structure of annealed ISPs that incorporate a metallic core, cavities, and copper oxide layers is revealed.

Devices based on semiconductor nanowires

Recently, nanoelectromechanical systems (NEMS) have attracted much attention due to their unique properties and possible applications that differ greatly from those of microelectromechanical systems. NEMS operating frequencies may achieve giga- and terahertz levels and their power consumption and heat capacity is extremely low. Moreover, integration levels may reach 1012 devices per cm−2. In this review, we present techniques for integrating semiconductor materials in NEMS. In particular, we examine fabrication, structure, properties and potential applications of two main classes of NEMS, namely, resonators and switches.

Non-magnetic heating for temperature control in scanning SQUID microscope

Abstract We have developed and built up a novel variable temperature (4–300 K, ± 0.05 K ) continuous flow cryostat for scanning SQUID microscopy (SSM) and other magneto-sensitive cryogenic applications. Temperature is controlled only by balancing cold and warm fluxes of He gas. In this way, any magnetic noise due to the temperature regulation system is eliminated.