Triplet positronium annihilation parameters in ethanol--pentene mixtures containing platinum

Positron lifetimes and intensities were determined for simulated hydrogenation reaction mixtures consisting of 1/2, 1/1, and 2/1 ethanol--pentene molar ratios to which 0.25 mg platinum powder were added. Annihilation parameters were determined upon addition of each successive component, yielding long lifetimes (tau3) of 4.1 +- 0.1 and 4.2 +- 0.1 ns for 1-pentene and trans-2-pentene (99% trans), respectively. Large I2 increases were observed for cis-2-pentene and for 1/2 ethanol--cis-2-pentene, both containing platinum