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I sobarle vapor-liquid equilibria have been measured for the system 2-propanol-toluene at 760 and 550 torr In a modified Yerazunls, Plowright, and Smola equilibrium still. The data have been tested for thermodynamic consistency by using the area test of Redllch-Kister and Herlngton and the differential test of Van Ness and Mrazek. Van Laar, Margules, and Wilson's parameters have been estimated for the binary system. Wilson's parameters were utilized to predict the azeotropic composition which was In good agreement with the experimental value.

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quasicontinuum") are less important at least up to n = 5 than direct twoor three-photon transitions. The evidence was as follows: (1) excitation by P10 or P16, where the first step has to be a two-photon transition, generates similar effects as observed at other wavelengths in flash spectroscopy; (2) the dissociation yield strongly depends at all investigated wavelengths on the laser intensity, indeed stronger than expected for an explanation invoking hole burning in the rotational contour; (3) the carbon isotope selectivity around P40 is determined by a bottleneck which apparently consists for 13CF3I in a direct two-photon transition in the first step and for 12CF3I in a (more difficult) direct three-photon transition in the third step. It would, however, be harder to understand why absorption to the background states (quasicontinuum) should be more difficult in the third step in 12CF3I than in the first step for 13CF3I.Thus, indirect evidence indicates the nature of the bottleneck transitions, up to the fifth photon. It is desirable, however, to observe these and higher states directly. This would be feasible with improved sensitivity of flash spectroscopy.Acknowledgment. I thank J. Hartmann for his expert assistance in setting up and performing the experiment, and K. L. Kompa for his support and discussions.

Rate constants for the transfer of energy from COiOO'I) to ethane and n-butane were measured using the laser induced fluorescence technique. The large magnitudes and the negative temperature dependence of the energy transfer rates indicate that near-resonant energy transfer processes caused by long range forces are responsible for the deactivation of the asymmetric stretching mode of CO 2 , It is shown that the combination bands in the alkanes are likely to receive the energy from CO 2 (OO'I). Using Sharma-Brau theory with Tam's modification and our experimental results, the square of the transition dipole matrix elements of V3+V6 and V 9 +v 1 I bands of ethane are estimated. At any given temperature in the range 300-730'K, the energy transfer cross section was found to increase linearly with n of C n H 2n + 2 • It is suggested that the absorption intensity of the combination bands of the alkanes also increases linearly with n in the spectral range 2300-2400 cm -I.