  We present adaptive optics high angular resolution ($\sim0.1\arcsec$)
spectroscopic observations in the 3 \um region of eight well known Herbig Ae/Be
stars with circumstellar disks. We detect the aromatic emission feature at 3.3
\um for four out of six of our objects with flared disks (HD 169142, HD 97048,
HD 100453, HD 100546), some weaker additional features at 3.4 and 3.46 $\mu$m
and nanodiamond features at 3.43 and 3.53 \um in two of our flared object (HD
100546 and HD 97048 respectively). We also detect hydrogen recombination line
at 3.74 \um in practically all objects. The emission in the polycyclic aromatic
hydrocarbons (PAHs) feature at 3.3 \um, additional and nanodiamond features in
the 3.4-3.5 \um region is, for the first time, spatially resolved in all the
sources where the features are detected. The full-width at half-maximum sizes
that we derive are typical of emission arising in a circumstellar disk. On the
other hand, the continuum emission is unresolved, with the exception of HD
97048 where it is marginally resolved. We compare the observed spatial
distribution of the 3.3 $\mu$m PAH feature and the adjacent continuum to the
predictions of a disk model that includes transiently heated small grains and
PAHs in addition to large grains in thermal equilibrium \cite[]{habart2004a}.
The model predicts that, as observed, the 3.3 $\mu$m PAH emission feature is
significantly broader than that of the adjacent continuum and that about 50% of
its integrated intensity comes from a radius $R<$ 30 AU. We find that the
predicted brightness profiles reproduce very well the observed ones. This
proves beyond doubt that the energetic 3.3 $\mu$m PAH emission feature takes
its origin in the inner disk regions.
