HIGHLIGHTS 2012  



               

          

Abnormal anti-Stokes Raman emission and infrared dichroism studies on poly(p-phenylenevinylene)/single-walled carbon nanotube composites
M. Baibarac, I. Baltog, J. Wery, S. Lefrant, JY Mevellec
Journal of Physical Chemistry C, Volume 116, Issue 48, 15 November 2012, Pages  25537-25545

Abstract
Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared spectroscopy (FTIR) in the grazing angle incident reflection geometry, new data concerning the abnormal anti-Stokes Raman emission (AASRE) and the molecular orientation of poly(p-phenylenevinylene) (PPV) deposited on metallic supports of Ag and Au are reported. The particular dependencies of the anti-Stokes Raman intensity on the Raman shift, the sample thickness, and the incident pump intensity are highlighted in this paper. In the spectral range of 800-1000 cm(-1), the FTIR spectra of PPV films deposited on Ag and Au supports show a dichroism similar to that reported for the free-standing PPV film. Significant differences are reported in the spectral range of 1400-1700 cm(-1) for the s- and p-polarized FTIR spectra of PPV films deposited on Au and Ag supports. The annealing treatment at 110 degrees C of the PPV precursor solution in the presence of single-walled carbon nanotubes (SWNTs) induces a noncovalent functionalization of carbon nanotubes with the polymer molecules, as evidenced by a decrease of the radial breathing mode intensity and a decrease in the strength of AASRE. The process of noncovalent functionalization of SWNTs with PPV induces a change of the orientation angle of the transition dipole moment vector for the absorption band at 835 cm(-1). This fact is explained on the basis of the pi-pi* interaction between the phenyl group of PPV and the sidewall of the nanotubes.





Sol-gel template synthesis of luminescent glass-ceramic rods
M. Secu, C.E. Secu and M. Sima
Journal of Nanoparticles Research, Volume 14, Issue 4, March 2012, pages 772
 
Abstract
We report an original way to prepare luminescent glass–ceramic microrods containing Eu3+ doped BaF2 nanocrystals by sol–gel chemistry within the pores of a polycarbonate template membrane. Structural characterization by scanning electron microscopy and X-ray diffraction has shown the formation of glass–ceramic microrods with 0.8μm diameter of and 10 μm length in which BaF2 nanocrystals of about 30 nm size are embedded. Photoluminescence measurements have indicated the incorporation of Eu3+ ions inside the BaF2 nanocrystals in a broad range of sites with low coordination symmetry. The comparison made with the bulk glass–ceramic indicated an influence of the dimensional constraints imposed by the membrane pores during xerogel formation and subsequent glass ceramization.