SPECTROSCOPY OF MRK-231 AND NGC-4151 IN THE 3 MU-M REGION

We present the results of spectroscopic studies of Mrk 231 and NGC 415 1 in the 3 mu m region. In the spectrum of Mrk 231, the strengths of t he 3.3 mu m emission feature and the 3.4 mu m carbonaceous absorption feature are smaller than expected. The weakness of the 3.3 mu m emissi on feature implies that large fractions of extended H-2 emission detec ted by Krabbe et al. (1997, AAA 67.158.058) are excited by SMBH-driven activities, and/or the 3.3 mu m emission carriers in the circumnuclea r starburst region are destroyed by being exposed to energetic radiati on from SMBH-driven activities. The weakness of the 3.4 mu m carbonace ous absorption feature may be due to the destruction of C-H stretching bonds in dust grains and/or lower abundance of C relative to Si, O, a nd Mg than that in our Galaxy, consistent to the fact that Mrk 231 is now undergoing starburst activities. In the spectrum of NGC 4151, we d etect the broad Bra: emission line, but do not detect the 3.3 mu m emi ssion feature nor the 3.4 mu m carbonaceous absorption feature. The no ndetection of the 3.3 mu m emission feature implies that nuclear starb urst activities just outside the obscuring torus are weak (L-FIR < 3.7 x 10(9) L.).