The preparation method of platinum-iridium tip and the device thereof relate to a scanning probe microscope. A simple, rapid and safe method for preparing platinum-iridium tip is provided. Ac voltage signal generation circuit, power amplifier circuit, corrosion current sampling circuit, AC signal amplifier circuit, AC RMS conversion circuit, DC signal amplifier circuit, data acquisition circuit, brake circuit and corrosion electrolytic cell. After annealing by hydrogen flame, one end of platinum-iridiume was wrapped and the other end was covered on the needle and connected with the working electrode. Two spectral pure carbon rods were inserted vertically into the corrosion solution parallel to the Pt-IR wire with the symmetrical center of the Pt-Ir wire. Insert the sealing end into the corrosion solution and keep the bare part in the depth of the corrosion solution; Monitoring the corrosion current to the Pt-Ir wire immersed in the corrosion solution exposed and encapsulated part of the junction is disconnected; After continuous corrosion, cut off the corrosion circuit and control the length to width ratio of the tip.
The probe of the SCANNING probe microscope determines the performance of the scanning probe microscope to a great extent. The size, shape and chemical composition of the probe directly affect the image quality of the scanning probe microscope. The sharper the tip, the more symmetrical the shape, the higher the image quality and resolution. At present, the materials used to prepare SPM tip mainly include hook wire (W), gold wire (Au) and platinum-iridium wire (Pt-Ir). Tungsten tip can obtain high-resolution images due to its hard texture, but it is easy to be oxidized in air and solution. The gold needle tip is chemically stable, but its texture is soft and easy to be damaged. Platinum-iridium alloy has the advantages of tungsten tip and gold tip because of its hard silk and strong corrosion resistance, wide potential window in solution. The commonly used methods of tip preparation in the laboratory include mechanical shear method and electrochemical corrosion method. The tip morphology obtained by mechanical shear method is asymmetric, which is put into the subsequent solution
SPM tip encapsulation brings difficulties; Electrochemical corrosion method of the equipment is simple, easy to operate, according to the nature of the voltage, and
It is divided into direct current electrochemical etching method and alternating current electrochemical etching method. In general, gold and tungsten tips are prepared by direct current electrochemistry.
The tip with small radius of curvature and relatively smooth surface can be easily made by etching method. However, because of its high chemical stability, high corrosion voltage and long corrosion time, The complexation of CN - is usually used to accelerate the corrosion speed of Pt-Ir materials. It is difficult to prepare tip by either DC or AC electrochemical etching method, especially to control the size and shape of tip. Therefore, it is necessary to develop a simple and rapid method to produce high quality Pt-Ir tip.
