화학공학소재연구정보센터
Journal of Chemical Physics, Vol.107, No.20, 8239-8251, 1997
Neutral and cation spectroscopy of fluorene-Ar-n clusters
Fluorene-Ar-n complexes formed in a pulsed supersonic jet have been studied in their S-1 state using two color REMPI spectroscopy with mass resolved detection. The appearance and shifts of the S-1 origins relative to the fluorene monomer are measured for cluster sizes up to n=30. The shifts and appearance of these bands are used to identify multiple conformations at low n and have indicated a shift from two sided clustering by Ar at low n to primarily one sided clustering at large n. The ionic ground state of the smaller clusters (n less than or equal to 6) are studied using mass analyzed threshold ionization (MATI) spectroscopy. The change of the ionization potentials as a function of cluster size has been determined. In the case of the fluorene-Ar-4 cluster, the MATI spectrum of two separate cluster conformations was measured, revealing significantly different ionization potentials. Vibrational dynamics has been studied in several smaller clusters (n less than or equal to 3) by measuring MATI and ZEKE spectra when pumping vibronic transitions in the fluorene chromophore. Significantly enhanced coupling of the chromophore to van der Waals modes is observed in going from n=1 to n=3. (C) 1997 American Institute of Physics. [S0021-9606(97)03144-9].