title: Precision frequency measurement of visible intercombination lines of strontium.
abstract: We report the direct frequency measurement of the visible 5s(2) 1S0-5s5p 3P1 intercombination line of strontium that is considered a possible candidate for a future optical-frequency standard. The frequency of a cavity-stabilized laser is locked to the saturated fluorescence in a thermal Sr atomic beam and is measured with an optical-frequency comb generator referenced to the SI second through a global positioning system signal. The 88Sr transition is measured to be at 434 829 121 311 (10) kHz. We measure also the 88Sr-86Sr isotope shift to be 163 817.4 (0.2) kHz.
authors.affiliation: Dipartimento di Fisica and LENS, Università di Firenze, INFM-UdR Firenze, Polo Scientifico, 50019 Sesto Fiorentino, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ferrari
authors.forename: P
authors.initials: P
authors.lastname: Cancio
authors.forename: R
authors.initials: R
authors.lastname: Drullinger
authors.forename: G
authors.initials: G
authors.lastname: Giusfredi
authors.forename: N
authors.initials: N
authors.lastname: Poli
authors.forename: M
authors.initials: M
authors.lastname: Prevedelli
authors.forename: C
authors.initials: C
authors.lastname: Toninelli
authors.forename: G M
authors.initials: GM
authors.lastname: Tino