We present the first constraints on the spin-dependent , inelastic scattering cross section of Weakly Interacting Massive Particles ( WIMPs ) on nucleons from XENON100 data with an exposure of 7.64 \times 10 ^ { 3 } kg day .
XENON100 is a dual-phase xenon time projection chamber with 62 kg of active mass , operated at the Laboratori Nazionali del Gran Sasso ( LNGS ) in Italy and designed to search for nuclear recoils from WIMP-nucleus interactions .
Here we explore inelastic scattering , where a transition to a low-lying excited nuclear state of ^ { 129 } Xe is induced .
The experimental signature is a nuclear recoil observed together with the prompt de-excitation photon .
We see no evidence for such inelastic WIMP- ^ { 129 } Xe interactions .
A profile likelihood analysis allows us to set a 90 % C.L .
upper limit on the inelastic , spin-dependent WIMP-nucleon cross section of 3.3 \times 10 ^ { -38 } cm ^ { 2 } at 100 GeV/c ^ { 2 } .
This is the most constraining result to date , and sets the pathway for an analysis of this interaction channel in upcoming , larger dual-phase xenon detectors .