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The adsorption and desulfurization of thiophene on clean and sulfided Ni(lll) surfaces were studied with LEED, AES, TPR, and RAIS. The RAIS data indicate that thiophene adsorbs with its ring parallel or nearly parallel to the surface below room temperature. On clean Ni(lll), thiophene polymerizes slightly above room temperature, as evidenced by paraffinic and aromatic C-H stretches in the reflection infrared spectrum and TPR product yields. Decomposition of the polymer aggregates produces a wide variety of hydrocarbons including C6 fragments at 470 K. On a more acidic sulfided Ni(lll) surface (0S = 0.19), thiophene appears to undergo electrophilic attack at an -carbon as evidenced by TPR products and by methane evolution from the reaction of 2,5-dimethylthiophene. An electrophilic attack by a surface metal atom at an -carbon of thiophene is discussed in terms of molecular orbital theory.

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The size and refractive index of individual smoke droplets have been measured by using a single-particle light-scattering instrument. Droplets of a given size were selected by use of a mobility classifier and then electrostatically charged. The measured scattered intensities were fitted to curves calculated from Mie theory to find the best values of the refractive indices. The refractive index of smoke from a moderately large, steady-state smolder reactor is found to be much less variable than that of cigarette smoke. Relative humidity is found to have a significant effect on the evaporation rate of the smoke droplets.