He obtained a doctorate on 11 December 1933, under the supervision of Curie, with a thesis title of Contribution to Spectrography by Crystalline Diffraction of Radiation.

In an article he published in 1947 he cited Paul Langevin and Francis Perrin as being major influences during his time in Paris.

[1][2] After returning to Portugal and the University of Lisbon, and still in receipt of scholarships, he devoted himself to investigating nuclear physics and X-ray spectroscopy.

In 1936 all civil servants were required by the Estado Novo to sign the following statement: "I declare on my honour that I am part of the order established by the Political Constitution of 1933, with an active rejection of communism and all subversive ideas".

[1][2][3] While in Paris he had collaborated with the Mainini Institute, which was pioneering the use of X-rays to study works of art, particularly in the Louvre museum.

From Pavia, Valadares moved to the Physics Laboratory of the Instituto di Sanitá Pubblica of Rome, where he used a spectrograph specially built for him to study the crystalline diffraction of radiation.

He also contributed in 1946 to the foundation of the magazine Gazeta de Física, aimed at Portuguese physicists and students, publishing several articles there.

[1][2][3] The Portuguese vonsul in Paris refused to renew the passports of Valadares, his wife and son in 1966, stating that this was on orders from Lisbon.

Valadares published, often in collaboration with his colleagues or students, more than 70 articles, mostly related to his research in atomic and nuclear physics.