Towards Probing a Variation of Fundamental Constants with Optical Clock Transitions of 127I2

Precision measurements of the molecular iodine optical transitions can be exploited for constraining a possible time variation of the fundamental constants. The sensitivities of the molecular frequencies to a variation of the proton-to-electron mass ratio and of the fine structure constant are calculated. Compact molecular iodine clocks, designed for space applications with improved stability performances, enable fractional frequency reproducibility at the 10−15 level. The comparison of the optical iodine clocks based on transitions at 532 nm, 514 nm and 502 nm with the Cs frequency standard can constrain a fractional time variation of the proton-to-electron mass ratio and of the fine structure constant at the 10−14 yr−1 level.