  Our knowledge of the diffuse emission that encompasses active regions is very
limited. In the present paper we investigate two off-limb active regions,
namely AR10939 and AR10961, to probe the underlying heating mechanisms. For
this purpose we have used spectral observations from Hinode/EIS and employed
the emission measure (EM) technique to obtain the thermal structure of these
diffuse regions. Our results show that the characteristic EM distributions of
the diffuse emission regions peak at log T = 6.25 and the cool-ward slopes are
in the range 1.4 - 3.3. This suggests that both low as well as high frequency
nanoflare heating events are at work. Our results provide additional
constraints on the properties of these diffuse emission regions and their
contribution to the background/foreground when active region cores are observed
on-disk.
