Improved FemtoScan XI scanning probe microscope
The improved microscope consists of a scanner, a measuring head (see Fig.1), a capillary holder and a cantilever holder. The design of the microscope which combines both scanning modes using a cantilever and a capillary is shown in Fig.1.
In the capillary mode a sample was placed into a cup with an electrolyte and inserted to a scanner with XY movement. Glass or quartz capillary is placed above the sample surface. A normal physiological solution or a saline solution (KSL solution) is used as an electrolyte. A thin silver wire AgCl-coated electrode is inserted into the inner cavity of the capillary. The second Ag/AgCl electrode is mounted on the external side of the capillary and shift voltage V0 is applied to it to support the ion current between the inner and outer electrodes. The ion current has a maximum value far from the sample surface and does not depend on a distance between a sample and a capillary.
The capillary radius may be reliably controlled by changing the parameters in a puller, such as heat, filament, velocity, delay and pull, which allows of producing the capillaries of desirable shapes and dimensions. We changed the "heat" parameter (which means the heat transferred by the laser to the capillary) in order to show that the visible radius of the capillary decreases with heating. It is a well known effect used in production of capillaries when a huge quantity of heat permits to make the capillaries of a smaller size. Besides, the capillary radius may be adjusted within the region of 7–150 nm by changing the laser power when pulling. The adjustment of other four parameters (filament, velocity, delay and pull) leads to more precise control of the radius to be produced.
The design of a measuring head includes a laser, a photodiode, electronic component boards, laser and photodiode control units, adjustment screws, a cantilever holder and a capillary holder. So, the installation operates both in a scanning probe microscopy mode and in a capillary one (see Fig.3).
Research of local chemical reactions in deposited films will be prolonged within a frame of the joint Russian and Iranian project. ■
The reported study was carried out with the financial support of the Russian Foundation for Basic Research within the framework of Scientific Project No. 17-52-560001.