Montagem e avaliação da técnica de microscopia fototérmica de reflexão para medida de propriedades termo-ópticas de metais

Abstract

The scientific innovation is showing itself to be necessary day after day. So the search for experimental techniques that allow perspectives of new studies are important. In this study, the goal is to build the Photothermal Microscopy of Reflection technique (PMR). It is intended to be a tool for the physics laboratories at UEM. It takes base on the dependency of the reflectance variation on the sample, when this sample is submitted to a modulated state of excitation, in this study case, done with the pump laser. After the system started working, tests were made in order to check its efficiency. In this process, metallic samples easily founded at the UEM's workshop were used. This samples were: aluminum, cooper, iron, stainless steel 316, brass and nickel. These initial tests had as goal to measure the photothermal signal according to the power and the modulation frequency of the pump beam. All measured samples showed a consistent behavior, directly proportional to the power and inverse to the frequency. Then, with a silver mirror covered in some spots with a black tape, a simple sample reflectivity map was made, just to test if the system was working properly. After that, some measures of reflectance were taken in two different temperatures, 25ºC and 75ºC, with assistance of a Peltier and a temperature controller, in order to calculate dR dT of the samples. We exhibited results obtained through the silicon sample, which was submitted to the same tests as the metals, and allow to conclude that, despite the short time and the assemble difficulties, improvements can be made to de system for studies of semiconductors by optical photoreflectance.