Studies on the light emitted by laser-trapped francium-210 ions have provided accurate data on transitions between atomic energy levels, similar to those predicted by quantum theory.
stˈʌdiz ɔnðə lˈaɪt ɪmˈɪɾᵻd baɪ lˈeɪzɚtɹˈæpt fɹˈænsiəm tˈuːhˈʌndɹɪd tˈɛn ˈaɪɑːnz hæv pɹəvˈaɪdᵻd ˈækjʊɹət dˈeɪɾə ˌɔn tɹænsˈɪʃənz bᵻtwˌiːn ɐtˈɑːmɪk ˈɛnɚdʒi lˈɛvəlz, sˈɪmɪlɚ tə ðoʊz pɹɪdˈɪktᵻd baɪ kwˈɔntəm θˈiəɹi.