Frequency measurement on the 5s5p 3P2-5s4d 3D3 transition of 88Sr atoms using the photon-momentum-transfer technique

We report a frequency measurement on the 5s5p P-3(2) - 5s4d D-3(3) transition of Sr-88 atoms at 2.9 mu m. The excitation spectra are obtained by measuring the photon momenta transferred to ultracold atoms. The transition frequency is determined to be 102 550 196 205(9) kHz using an erbium fiber-based optical frequency comb. We numerically investigate possible frequency corrections by taking an acceleration of atoms and attenuation of the excitation light into account. This measurement technique is particularly useful for transitions where laser-induced fluorescence is difficult to observe but the spatial imaging of atoms is possible.