Precision measurement of 25Mg+-ion D1 and D2 transition frequencies

Precision measurement of Mg+ ion D1 and D2 doublet transition frequencies plays a significant part in the study of space-time variation of fundamental physical constant alpha. Here, we report a precision measurement of 25Mg+ ion D1 and D2 doublet transition frequencies using the decoherence-assisted spectroscopy method with the full use of spontaneous emission signals to improve the detection sensitivity. We obtain the D1 and D2 transition frequencies of 25Mg+ with uncertainties of 0.12 and 0.24 MHz, respectively, which are one third of that in [A. Ozawa et al., Nat. Commun. 8, 44 (2017)]. Simultaneously, we obtain the experimental and theoretical values of the 25Mg+ hyperfine structure constants in this work. The differences between the mea-sured magnetic dipole constants AP1/2 = -102.87(8 ) MHz, AP3/2 = -18.74(9 ) MHz and the theoretical values AP1/2 = -102.02(94 ) MHz, AP3/2 = -19.46(45 ) MHz are within 2o-, while the measured electric quadrupole constant BP3/2 = 24.54(45) MHz and the theoretical value of BP3/2 = 22.67(32) MHz shows a difference of more than 2o-, indicating that considerations of more physical effects in theoretical calculation, such as the possible capture of electron correlations, is required.