Raman spectra of polymeric photoconductive copper organoacetylides (RCCCu)x differ substantially from the spectra of other CuI or AgI compounds which lack photoconductive properties. Also, there is a significant redistribution of band intensities in the Raman spectra of the copper organoacetylides compared with the spectra of the parent acetylenes. The triple bond stretching vibration, v(CC), at ca 1950−1900 cm−1, v(C‐C) at ca 950−700 cm−1 and the lines at ca 600−500 cm−1, caused by deformations of angles between the multiple and single bonds, in the spectra of copper acetylide exhibit an increase in intensity by a factor of 10–100 compared with the spectra of parent acetylenes RCCH. The vibrational bands characteristic of the R substituent itself seem to be very weak in comparison with the unusually strong band of the acetylide in the lower Raman shift range. The origin of these unusual Raman intensities in copper organoacetylides is discussed.

The magnetic phase diagram for CrFe alloys was determined by neutron scattering and low-field magnetisation. Two critical concentrations were found as the state of magnetic order evolved from itinerant antiferromagnetism for Fe concentrations less than CA = 16.0 f 0.5% to ferromagnetism for Fe concentrations greater than cF = 19.0 f 0.5%. Spin-glass behaviour was observed between the two critical concentrations.The onset of ferromagnetism was studied by neutron small-angle scattering. Analysis of the concentration and temperature dependence of the magnetic correlation range below cF suggested that a geometrical element is involved in the development of ferromagnetic longrange order; these results were in semi-quantitative agreement with models for the percolation multi-critical point. The bulk magnetic properties of alloys between the two critical concentrations were consistent with a simple fine magnetic particle model of percolation clusters of Fe moments fluctuating against barriers arising from magnetostatic shape anisotropy.

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