presence of C=0 and SiMe but no Si-O-Si groups. UV maxima was found at 305 nm.The present new method of preparing polysilylenes is quite versatile in designing new polymers. The work is supported in part by the Ministry of Education, Science, and Culture (Grant-in-Aid for Special Project Research, No. 63106003).

The dynamics of the dec^y of the tautomer species and triplet state of 3-hydroxyflavone have been studied in detail by transient absorption, two-step las4r excitation, and steady-state photolysis experiments. The decay of the tautomer species is observed to be 6.9 X 104 s'1 in «¡heptane at room temperature and is only slightly dependent on various chosen nonpolar solvents. This rate is more than p orders of magnitude smaller than the rate of excited-state proton transfer, in agreement with the experimental results reported by Itoh et al. The bimolecular quenching rate constant of the tautomer of 3-hydroxyflavone by oxygen is determine^t o be 3.2 x 109 M"1 s"1 in «-heptane. Two proposed mechanisms that involve the tautomer ground state and triplet state for the reverse proton transfer are presented in order to interpret the experimental results. An observed T[ -T" absorption in the transient absorption spectrum at -395 nm is assigned as originating from the normal species with a 7.2-µ8 lifetime in «-heptane. The yield of the triplet states is determined to be 0.18 ± 0.02 as a lower limit.

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