Charge Density Waves , Spin D 8 nSlty Waves , and Pelerls Distortions in OncDimensional Metals . 2 .

of the S, state in place of the second C, value in eq 9. Note that the first C, value must be that of the So state since the distribution of the CF3H molecule is the same as that in the ground state duing the light absorption. In this way, the stabilization energy in the SI state during the light absorption is calculated to be 904 cm-]. With these values, the bathochromic shift due to the complexation of one CF3H molecule to DMABN is estimated to be 274 (=904 630) cm-’. Compared with the assumed bathochromic shifts, 225 cm-’, the agreement is excellent if one considers the uncertainty in the potential function and other possible errors. (F) Implication of the Present Study. It becomes clear in the present study that, in low-density supercritical fluid, the solvent molecules do not disperse uniformly but aggregate around the solute, and the average number of aggregating molecules is dependent on their interaction potential. This fact, in turn, suggests that we can control the solvation number on the average by changing the density of supercritical fluid, and hence we are able to study the chemical equilibria or reactions of the particular solute molecule which is solvated by a specified number of solvent molecules. Concerning the nature of the charge-transfer state, the present experiment negates the view that the 1:l solvent-solute exciplex is the source of the so-called anomalous (CT) emission. If the 1 : 1 complex is important, we must observe the anomalous emission even at the low CF3H density because, at the density of 0.023 g/cm3, most of the DMABN molecules are solvated by one CF3H molecule. At the temperature of the supersonic free jet (below 10 K), it might be difficult for the 1:l complex to form the exciplex owing to the insufficient energy for the solvent to move into the best location for the exciplex formation.* However, it is now demonstrated that even at elevated temperatures, the exciplex is not formed. On the contrary, when we increase the polarity of the environment for the solute DMABN by increasing the density, the CT emission appears clearly. Its peak wavelength moves toward longer and longer wavelength as the density of the supercritical fluid increases. This fact is most naturally rationalized in terms of the intramolecular charge-transfer state formation which is facilitated by the increase of the environmental polarity.