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This research aimed to investigate the misconceptions on nuclear physics topics. Misconceptions are defined as ideas whose meaning departs from what is commonly accepted by scientific consensus. A total of 34 high school students of the Federal Institute of Education, Science and Technology of São Paulo (IFSP), Brazil, answered a questionnaire on atomic model, radiation and radioactivity themes. The results showed that more than half of the students used similar representations to the Rutherford model when they had to draw an atom. In addition, at least 60% of the students had heard about radiation but could not explain the scientific meaning of the term. Also, it was noted in the research the influence of knowledge acquired by students outside the classroom by mentions made on nuclear fission, a topic not covered in the curriculum, and the frequent use of the Rutherford atomic model, ideas often conveyed by the media. Thus, there is a need for further discussion by teachers and teachers in training on the inclusion of nuclear physics topics in the high school curriculum.

Abstract:In order to investigate optical properties of alexandrite, the present work deals with the influence of thermal annealing on optical absorption and luminescence spectra of natural samples. The exposure time to heat treatment at 1000 o C is taken into account. Possible migration of Cr 3+ ions from Al 1 (inversion site) to Al 2 (reflection site) is detected. Sample composition is obtained through Scanning Electron Microscopy (SEM) measurements and points to a rearrangement of Cr +3 and Fe 3+ ions in the alexandrite crystalline structure, under thermal annealing influence. This feature may be used to control the optical properties of natural alexandrite, which can be associated to the observed laser emission effect.

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