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Pr₂Zr₂O₇ is a quantum spin ice candidate, where a splitting of the Pr³⁺ non-Kramers ground state doublet was suggested as an origin of the transverse field component leading to the exotic physics in this material [1]. We performed the low temperature Raman scattering experiments on Pr₂Zr₂O₇ single crystals to probe the crystal electric field excitations and phonons. We directly observed a splitting of the excited state doublet at around 55 meV which originates from vibronic coupling of the E_g doublet with a phonon. We deduct a 1 meV splitting of the ground state E_g doublet from the line shape of the excitation to the first excited A_1g state. The well-defined splitting of the ground state suggests that static or low frequency dynamic deviation of Pr³⁺ environment from D_3d symmetry causes the splitting.

[1] J-J Wen, et al., Phys. Rev. Lett 118 (10), 107206