wˈʌn ʌvðə bˈɛstnˈoʊn ˌæplɪkˈeɪʃənz ʌvðə pjˈʊɹ ˈɛlɪmənts ɪz ðə jˈuːs ʌv ɹuːbˈɪdiəm ænd sˈiːsiəm ɪn ɐtˈɑːmɪk klˈɑːks, ʌvwˈɪtʃ sˈiːsiəm ɐtˈɑːmɪk klˈɑːks fˈɔːɹm ðə bˈeɪsɪs ʌvðə sˈɛkənd.
One of the best-known applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks form the basis of the second.