Processing of polycyclic aromatic hydrocarbons in molecular-loop regions
  near the Galactic center revealed by AKARI
  We present the AKARI mid-infrared diffuse map of an area of about 4 deg x 3
deg near the Galactic center in the 9 um band. The band intensity is mostly
attributed to the aromatic hydrocarbon infrared emissions of carbonaceous
grains at wavelengths of 6.2, 7,7, 8.6, and 11.3 um. We detect the 9 um
emission structures extending from the Galactic plane up to the latitude of
about 2.5 deg, which have spatial correspondence to the molecular loops
revealed by the NANTEN 12CO (J=1-0) observations. We find that the surface
brightness at 9 um is suppressed near the foot points of the CO loops. The
ratios of the 9 um to the IRAS 100 um brightness show significant depression
near such bright regions in the CO emission. With the AKARI near-IR 2.5--5 um
spectroscopy, we find that the 3.3 um aromatic hydrocarbon emission is absent
in the region associated with the loop. These suggest the processing and
destruction of carbonaceous grains in the CO molecular loops.
