  EIT waves are a wavelike phenomenon propagating outward from the coronal mass
ejection (CME) source region, with expanding dimmings following behind. We
present a spectroscopic study of an EIT wave/dimming event observed by
Hinode/EIS. Although the identification of the wave front is somewhat affected
by the pre-existing loop structures, the expanding dimming is well defined. We
investigate the line intensity, width, and Doppler velocity for 4 EUV lines. In
addition to the significant blue shift implying plasma outflows in the dimming
region as revealed in previous studies, we find that the widths of all the 4
spectral lines increase at the outer edge of the dimmings. We illustrate that
this feature can be well explained by the field line stretching model, which
claims that EIT waves are apparently moving brightenings that are generated by
the successive stretching of the closed field lines.
