Electrochemical (EC) technologies are at the center of constantly growing attention as it is the means for controlled modifications of the surface even with atomic precision. EC deposition is an approach extensively used for producing thin metal films with exceptional properties. Alternatively, EC dissolution enables imitation and examination of corrosion processes.
Monitoring Nanoscale Changes Using NTEGRA
Scanning probe microscopy, namely, scanning tunneling microscopy (STM) and atomic force microscopy (AFM), techniques make it possible to observe the nanoscale changes taking place at the surface during an EC modification. The NTEGRA nanolaboratory enables conducting a variety of EC experiments in highly specialized conditions.
To illustrate this, the images in Figure 1 show that the external magnetic field (MF) greatly affects the Cu deposition process. Owing to magneto-hydrodynamic (MHD) electro-deposition + convection and some other effects of the interaction of ions with external MF, the electrodeposition takes place much readily.
Figure 1. AFM images of copper films electro-deposited on Au (111) without magnetic field (a1) and in magnetic field (B = 0.1 T) (a2). Scans were obtained by using CSG01 probes. The in situ AFM investigations were performed with the NTEGRA Aura setup in the MFM configuration. Scans size 2 x 2 µm.
Figure 2 shows the possibilities of STM. During Cu electro-deposition, the formation and destruction of a lattice with the sulfate anions and the copper adatoms can be viewed. Consequently, the sulfate anions are replaced by the Cu monolayer. The in situ STM investigations were carried out using the NTEGRA setup designed for electrochemical measurements.
Figure 2. STM images of the underpotential deposition (UPD) of copper on Au (111) in sulfate solution before negative shifting the sample potential (b1) and afterward (b2). After Fourier filtration (b3, b4), it is obvious that negative shifting leads to the replacement of sulfate anions by Cu adatoms: atomic structure typical for sulfate (v3 x v3)R30° changes to structure (1 x 1) typical for pseudomorphic Cu monolayer. Scans size 30 x 30 nm.
EC cell for AFM and STM experiments in the controlled environment offers thermostabilization. The hermetic cell is optionally available.
Bipotentiostat is a computer-controlled module for performing electrochemical experiments in galvanostatic, potentiodynamic, and potentiostatic modes.
NTEGRA AURA is a scanning probe microscope for investigating the conditions of low vacuum and controlled environment. The Q-factor of the cantilever in vacuum increases, thereby realizing the accuracy, reliability, and sensitivity of “probe-sample” light force measurements. In this case, the variation from atmospheric pressure to 102 Torr vacuum results in the ten-fold gain of Q-factor.
By more vacuum pumping, Q-factor achieves its plateau and only changes slightly. Hence, NTEGRA AURA presents the optimal “price/quality” ratio: it requires much less time compared to the high-vacuum devices—merely a minute—to get the vacuum that is required for the 10-fold Q-factor increase. At the same time, the system is compact and easy to maintain and operate. Being the NTEGRA platform product, NTEGRA AURA is compatible with over 40 different AFM techniques and has an optical system with 1 µm resolution and integrated closed-loop control for all the axes.
NTEGRA AURA setup in the MFM configuration enables performing EC experiments in external magnetic field.
Traditional high-resolution AFM “Golden” silicon probes (CSG01) for contact mode are available with different coatings (TiN, PtIr, Au, Al, Au, diamond doped conductive, etc.) and tipless. Probes having no coating and for non-contact modes can also be supplied.
This information has been sourced, reviewed and adapted from materials provided by NT-MDT Spectrum Instruments.
For more information on this source, please visit NT-MDT Spectrum Instruments.