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Abstract: Langmuir films of a side-chain ferroelectric liquid crystalline polysiloxane of 4-(10-undecen-1-oyloxy)-4′-(s)-2-methybutoxybiphonyl (P(III)) and its monomer 4-(10-undecen-1-oyloxy)-4′-(s)-2-methybutoxybiphonyl (M(III)) were transferred successfully at surface pressures of 11 and 8 mN m−1 onto solid substrates, respectively. The π–A isotherms of P(III) and M(III) have shown that they have different properties on the air/water interface. The monolayer film on the air/water interface of M(III) shows a clear orientation transition while that of P(III) does not. Infrared (IR) transmission and reflection–absorption spectra of Langmuir–Blodgett (LB) films of P(III) and M(III) indicate that the long axis of the chromophoric part of P(III) is almost perpendicular to the substrate surface while that of M(III) is tilted with respect to the substrate normal. The alkyl parts of both P(III) and M(III) are tilted considerably from the substrate normal. It also indicated from the IR spectra of the LB films that the liquid crystalline molecules of P(III) and M(III) are highly ordered and oriented in the monolayer and multilayer LB films. Temperature-dependent IR experiments show that the alkyl chains have anisotropic property in both P(III) and M(III). This may be due to the influence from the chiral groups of the molecules rather than from the substrates, and the side chains of P(III) play an important role in enhancing the anisotropic property. [Copyright &y& Elsevier]

Abstract: In this paper, triangular and hexagonal silver nanoplates were prepared on the surface of quartz substrate using photoreduction of silver ions in the presence of silver seeds. The obtained silver nanoplates were characterized by atomic force microscopy and UV–vis spectroscopy. It was found that the silver seeds played an important role in the formation of triangular and hexagonal silver nanoplates. By varying the irradiation time, nanoplates with different sizes and shapes could be obtained. The growth mechanism for triangular and hexagonal nanoplates prepared on quartz substrate was discussed. [Copyright &y& Elsevier]

Water-induced changes in the morphology and optical properties of an ultrathin Ag film (3 nm thickness) have been studied by use of ultraviolet–visible (UV–Vis) spectroscopy, atomic force microscopy (AFM) and surface-enhanced Raman scattering (SERS) spectroscopy. A confocal micrograph shows that infinite regular Ag rings with almost uniform size (4 μm) emerge on the film surface after the ultrathin Ag film was immersed into water. The AFM measurement further confirms that the Ag rings consist of some metal holes with pillared edges. The UV–Vis spectrum shows that an absorption band at 486 nm of the Ag film after the immersion in water (I-Ag film) blue shifts by 66 nm with a significant decrease in absorbance, which is attributed to the macroscopic loss of some Ag atoms and the change in the morphology of the Ag film. The polarized UV–Vis spectra show that a band at 421 nm due to the normal component of the plasmon oscillation blue shifts after immersing the ultrathin Ag film into water. This band is found to be strongly angle-dependent for p-polarized light, indicating that the optical properties of the ultrathin Ag film are changed. The I-Ag film is SERS-active, and the SERS enhancement depends on different active sites on the film surface. Furthermore, it seems that the orientation of an adsorbate is related to the morphology of the I-Ag film. [Copyright &y& Elsevier]

A self-assembled film of ruthenium phthalocyanine (RuPc) fabricated on a silver substrate pre-modified with a monolayer of 4-mercaptopyridine (PySH) or 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BPENB) was studied by ultraviolet-visible (UV-Vis) and surface enhanced Raman scattering (SERS) spectroscopy. PySH or BPENB was used as a ligand to link RuPc since they not only modify the silver substrate, but also deliver a pyridyl group pointing out from the silver surface. Therefore, we can explore the relationship between the structure and orientation of metallophthalocyanine and the substrate modified by the two kinds of organic-monolayers with the different conjugates and molecular lengths. UV-Vis bands due to the organic-monolayer (PySH or BPENB) modified silver films shift to longer wavelengths and a new band arising from the metallophthlocyanine appears, suggesting the binding of RuPc to PySH/BPENB, as well as the interaction between the marcocycle of RuPc and the ring of PySH/BPENB. Vibrational bands arising from both the RuPc and PySH/BPENB moieties appear clearly in the SERS spectra of the RuPc–PySH/BPENB composite films, indicating that RuPc is successfully assembled on the top of PySH/BPENB film. The shifts and relative intensity changes of bands due to PySH or BPENB in the SERS spectra imply the binding of the metallophthalocyanine to the pyridyl group in the composite films. Furthermore, the comparison of the SERS spectra revealed that the orientations of PySH and BPENB in the two kinds of composite films are different; the BPENB moiety in the RuPc–BPENB composite film is more perpendicular to the silver surface compared with the PySH moiety in the RuPc–PySH composite film. [Copyright &y& Elsevier]