Palladium-catalyzed polycondensation between dihalo aromatic compounds X-Ar-X (3hexyl-2,5-diiodothiophene, 2,5-dibromoselenophene, and 3,4-dinitro-2,5-dibromothiophene) and diethynyl aromatic compounds HC=C-Ar'-C=CH (2,5-diethynylpyridine, 3-hexyl-2,5-diethynylthiophene, and p-diethynylbenzene) in the presence of triethylamine gives soluble -conjugated poly(aryleneethynylene) (PAE) type polymers (-Ar-C=C-Ar'-C=C-)" when Ar and/or Ar' contains the long alkyl substituent and/or pyridine ring. The PAE type polymers are obtained in high yields (86-100 %), have molecular weights of 9.6 X 10 59 X 104 and pv (degree of depolarization) values of 0.005-0.034 as determined by the light scattering method, and show absorption bands in the range 350-462 nm, which are shifted from the absorption bands of the corresponding aromatic units (HArH and HAr'H), indicating the occurrence of -conjugation along the polymer chain. The polymers exhibit fluorescence in solutions, and the position of the fluorescence is shifted to a longer wavelength in films of the polymers, suggesting the formation of excimer-like adducts in the solid state. The polymer films give a (3) (third-order nonlinear optical susceptibility) value of about 5 x 10"u esu when the Ar group has the hexyl group. Cyclic voltammetry of the PAE type polymers indicates that they receive reduction (n-doping) at about -2 V vs Ag/Ag+ whereas oxidation (p-doping) of the polymer is difficult presumably due to the electron-withdrawing effect of the -C=Cgroup. HBr addition to the -C=Cgroup of the polymer gives a polymer having a -CH=CH(Br)group, which can be further converted into ester and amide groups.

x-Conjugated poly(aryleneethyny1ene) type polymers fC-C-Ar-C=C-Ar'),, (Ar and/or Ar' = pyridine-2,5-diyl or al kylsubstituted arylene) synthesized by a palladium-catalysed coupling reaction are soluble in organic solvents and processable to make good thin films by casting, have large refractive index increment (AnlAc = 0.29-0.38), and exhibit photoluminescence as well as fairly st-mg third harmonic generation, $3) value of about 10-10 esu.

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Tokapole I1 is a Tokamak with a four-node poloidal divertor. Impurity concentrations, line radiated power, and impurity behavior have been studied in Tokapole I1 discharges w i t h two W spectrometers, one of which uses a miaochannel plate to acquire the VUV spectrum (4OC-1300 A) during a single discharge. Oxygen ( 3 4 % of the electron density) is the dominant impurity, and the measured total radiated power is 15-30% of the ohmic input power. Sheath potentials and arcs evidently play a dominant role in the generation of the observed metallic impurities, because the 15-20 eV plasma ions have essentially no sputtering yield. An impurity doping technique has been used to measure the impurity concentrations and the contributions of the various low-Z impurities to the total radiated power. From the time history of the oxygen ions, T, is estimated to be about 100 eV. A model of impurity behavior in a plasma with a magnetic limiter is presented.

Pd-catalyzed coupling reactions with dihaloaromatic compounds X-Ar-X and diethynylaromatic compounds HC≡C-Ar′-C≡CH give new soluble π-conjugated polymers when Ar and/or Ar′ group is pyridine-2,5-diyl or has a long chain alkyl substituent.