Identification of the J^π=1^- two-phonon state of ⁸⁸Sr

The linearly polarized γ-ray beam produced by the HIγS facility has been used to determine the parity of two previously known dipole excitations in ⁸⁸Sr. The azimuthal asymmetry of γ rays produced in the process of nuclear resonance fluorescence indicated that the dipole state at 4.742 MeV, recently discussed as a new form of M 1 excitation, is in fact a 1^- (E1) state. The 1^- state at 4.742 MeV must, therefore, be reconsidered as the J^π = 1^-1 member of the quadrupole-octupole coupled two-phonon multiplet. A second state at 7.53.5 MeV was also assigned J^π = 1^-.