Polar, non-coordinating ionic liquids as solvents for the alternating copolymerization of styrene and CO catalyzed by cationic palladium catalysts

The palladium-catalyzed copolymerization of styrene and CO in an ionic liquid solvent, 1-hexylpyridinium bis(trifluoromethanesulfonyl) imide, gave improved yields and increased molecular weights compared to polymerizations run in methanol.

Dynamic in situ optical and magneto-optical monitoring of the growth of Co-Pd multilayers

In situ ellipsometry and Kerr polarimetry have been used to follow the continuous evolution of the optical and magneto- optical properties of multiple layers of Co and Pd during their growth. Films were sputter deposited onto a Pd buffer layer on glass substrates up to a maximum of N = 10 bi-layer periods according to the scheme glass/Pd(10)Ar x (0.3Co/3Pd) (nm). Magnetic hysteresis measurements taken during the deposition consistently showed strong perpendicular anisotropy at all stages of film growth following the deposition of a single monolayer of Co. Magneto-optic signals associated with the normal-incidence polar Kerr effect indicated strong polarization of Pd atoms at both Co-Pd and Pd-Co interfaces and that the magnitude of the complex magneto-optic Voigt parameter and the magnetic moment of the Pd decrease exponentially with distance from the interface with a decay constant of 1.1 nm(- 1). Theoretical simulations have provided an understanding of the observations and allow the determination of the ultrathin- film values of the elements of the skew-symmetric permittivity tensor that describe the optical and magneto-optical properties for both CO and Pd. Detailed structure in the observed Kerr ellipticity shows distinct Pd-thickness-dependent oscillations with a spatial period of about 1.6 nm that are believed to be associated with quantum well levels in the growing Pd layer.

Dynamic, in situ optical, magnetic and magneto-optical monitoring of the growth of Co/Au and Pd/Co/Au multilayer systems

The growth of magnetron sputtered Co/Au and Pd/Co/Au superlattices on Au and Pd buffer layers, deposited onto glass substrates, has been monitored optically and magneto-optically in real time, using rotating analyser ellipsometry and Kerr polarimetry, at a wavelength of 633 nm. The magneto-optical traces, combined with ex situ and in situ hysteresis loops, provide a detailed and informative fingerprint of the optical and magnetic properties of the films as they evolve during growth. For Co/Au, oscillations in the polar magneto-optical effect developed during the deposition of An overlayers on Co and these may be attributed to quantum well states. However, the hysteresis measurements show that the magnetic field required to maintain saturation magnetization throughout the experiment was larger than available in situ, introducing a degree of confusion concerning the interpretation of the data. This problem was overcome by the incorporation of Pd layers into the Co/Au structure, thereby eliminating variation in magnetic orientation during growth of the Au layers as a contributory factor to the observations.