INFRARED-SPECTROSCOPY OF ANILINE-X (X=N-2, CH4, CHF3, CO) CLUSTERS AND THEIR CORRESPONDING CLUSTER CATIONS IN THE NH2-STRETCHING VIBRATION REGION

The NH2-stretching vibrational modes of four different aniline-X clust ers (X = N-2, CH4, CHF3, CO) and their corresponding cluster cations w ere investigated by ion-depletion spectroscopy. The observed frequency shifts of the neutral clusters have been found to be very small, and to be proportional to the red shift of the origin of the S-1 <-- S-0 e lectronic band. This result suggests that the molecules interact with the aromatic ring system of aniline. The shifts of the cation species are larger than those of the neutral species, especially for aniline-C H4+. The proton affinity of the interacting molecule has been found to be correlated to the frequency shift except for CHF,. The different b ehavior of the cation species from the neutral ones suggests that the main interaction force in the cation clusters is different from that i n the neutral ones. The possibility of the hydrogen bond interaction i s discussed.