Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Material Physics 1615.1.3.9 Structural and magnetic property study of Transition metal doped oxidesTransition metal doped oxides have attracted considerable interest as promising diluted magneticsemiconductors owing to the possibility of inducing room temperature ferromagnetism for advancedspintronics applications. Thin films will be grown by sputtering ZnO and Co simultaneously andalso sequentially. Structural studies will be carried out with X-ray reflectivity, SEM-EDAX andXRD and magnetic measurement will be carried with SQUIDS KunduSP5.1.3.10 Linear and nonlinear optical absorption in copper nanocluster-glass compositesCopper nanoclusters have been formed in fused silica glasses under 100 keV and 200 keV Cu +ion implantations. UV Vis spectroscopy measurements have revealed prominent linear absorptionbands at characteristic surface plasmon resonance (SPR) frequency signifying the appreciableformation of copper colloids in glass matrices even without thermal treatments. Ion-induced colloidformation in glasses without thermal treatments is probably the first time observation in thepresent study. Subsequent annealing of the implanted samples has resulted in the further enhancementof the absorption bands. Formation of copper nanoclusters without thermal annealing can beattributed to the relatively high mobility of copper atoms even at ambient conditions. The transmittancemeasurements made by Z-scan technique have revealed saturable absorption signifyingthe nonlinear optical responses of the metal nanocluster-glass composites.Binita Ghosh, Purushottam Chakraborty, Satyabrata Mohapatra†, Pushpa Ann Kurian†, C Vijayan†SP5.1.3.11 Secondary ion mass spectrometry of MCsn + molecular ion complexesExcellent detection sensitivity, high dynamic range and good depth resolution make the SIMS techniqueextremely powerful for the analysis of surfaces and interfaces. However, a serious problem inSIMS analysis is its matrix effect that hinders the quantification of a certain species in a sampleand consequently, probing the composition of surfaces or interfaces by SIMS is greatly hindered.Appropriate corrective measures are therefore, needed to calibrate the secondary ion currents intorespective concentrations for accurate compositional analysis. Working in the MCs + -SIMS mode(M element to be analyzed, Cs + bombarding ions) can circumvent the matrix effect. The quantitativepotential of the MCs + -SIMS method is understood by assuming that an MCs + ion isgenerated by the combination of a secondary neutral M0 atom with a re-sputtered Cs + ion in thenear-surface region. The emission process for the species M0 is thus decoupled from the subsequentMCs + ion formation process, in analogy with the ion formation in secondary neutral massspectrometry (SNMS), resulting in a drastic decrease in matrix effect. Although this technique hasfound its applicability in direct quantification, it generally suffers from a low useful yield. In such