Fluorescence spectra of supercritical carbon dioxide (ScCO2) containing a small amount of pyrene (10-5 M) and N,N-dimethylaniline (DMA, 10-5 M) were measured in the pressure range of 8-27 MPa at 318.15 K. Emission from intermolecular exciplexes of pyrene/N,N-dimethylaniline were clearly observed in supercritical carbon dioxide, and its intensity decreased as the fluid pressure (density) increased. The fluorescence spectra at various pressures were similar to those of pyrene (10-5 M)/N,N-dimethylaniline (10-2-10-4 M) in n-hexane with varing the concentration of N,N-dimethylaniline (Okada and Mataga). These results suggested that pyrene molecules were preferentially surrounded by N,N-dimethylaniline molecules in ScCO2, and the local distribution of DMA around pyrene varied remarkably by changing the pressure in ScCO2.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry