Fourier transform infrared spectrum of ammonia adsorbed on C60 films

Fourier transform infrared (FTIR) spectra of ammonia adsorbed on high surface area evaporated C60 films were investigated at 170–180 K. Absorptions were found in the ν1, ν2, ν3 and ν4 regions. The frequencies of ν1, ν4 and ν3 absorption bands are shifted to lower values and the frequency of ν2 to higher value compared to the gas phase. An additional band at 542 cm−1 assigned to the rocking mode, usually found in solid ammonia, was also observed. The largest shift, 196–160 cm−1 towards higher frequencies, was found for the ν2 band. This led to the conclusion that the ammonia molecule is attached to the surface through the lone pair electrons of the nitrogen where partial donation to the C60 surface occurs.