  We present measurements of diffuse ultraviolet emission in the dwarf
irregular galaxy Holmberg II obtained with the UltraViolet Imaging Telescope
(UVIT) onboard AstroSat. With a spatial resolution of 1.2 to 1.6 arcsec, these
are the highest resolution UV observations of the galaxy to date. We find that
diffuse emission accounts for 70.6 % (58.1 %) of the total FUV(NUV) emission,
respectively. We perform a UV-IR correlation study of the diffuse emission in
this galaxy using infrared observations from Spitzer Space Telescope and
Herschel Space Observatory for selected locations, free of detectable bright
point sources. The strongest positive correlation between FUV and IR is
observed at 70 micron for high HI density locations, indicating that warm dust
grains dominate the IR emission, in agreement with earlier studies, while NUV
is better correlated with 160 micron emission associated with cold dust grains.
Low HI density regions or cavities, do not show any significant UV-IR
correlation except at 160 micron, implying either the presence of colder dust
grains in cavities, being irradiated by the general radiation field, or
insufficient amount of dust. The dust scattering contribution in high HI
density regions, estimated using a single scattering model with foreground dust
clouds with LMC reddening, gives best-fit albedo and asymmetry factor values of
0.2 and 0.5, respectively, in reasonable agreement with the theoretical
predictions for LMC dust. Our model derived scattering optical depths in the
FUV range from 0.02 to 0.12, implying the medium is optically thin. Therefore,
in high HI density regions, dust scattering can be one the sources of the
observed diffuse UV emission, apart from possible contributions from molecular
hydrogen fluorescence, However, the diffuse UV component in HI cavities can
only be explained via other mechanisms, such as two photon emission.
