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Publication costs assisted by the Petroleum Research FundLuminescence quenching of Ru(b~y),(cN)~ and R~( p h e n )~( C N )~ (bpy = 2,2'-bipyridine and phen = 1,lOphenanthroline) by 19 transition metal complexes is reported. The neutral cyano complexes have properties which permit them to supplement the widely used [Ru(bpy)3I2+ and [R~(phen)~]'+ sensitizers. In addition to their intense, long-lived fluid solution emissions, the cyano complexes are free of ion-pairing problems and the large charge dependence of quenching rates with the tris complexes. The excited state energies of the cyano species can also be tuned significantly by solvent variation. Quenching is predominantly by diffusion. For Co2+, Ni2+, and Cu2+, however, associational quenching by formation of a cyanide bridged species is important. Decay times, excited state energies, Stern-Volmer constants, bimolecular quenching constants, and association constants are reported. Quenching appears to be by energy and electron transfer.

We report here observations of laser-induced non-linear light scattering, both eIaslfc and inelastic (hyper-Raman), from methane, etbane and ethylene. Observations on several other molecules, mainly substituted metbanes and ethanes, wiII be reported elsewhere. 1 system. Thus a pure P[ 3f to leak into the detection spectrum is not obtained. The most striking change is the neariy complete loss in intensity of the v7 (bending) Vibration and the absence of the second harmonic band. This suggests that the two effects may not be independent, and that the unexpected second harmonic 221 Volume 7, number 2 CHEMICAL PHYSICS LETTE-33 -

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