Showing papers by "Chhagan Lal published in 2013"
06 Dec 2013
TL;DR: In this paper, the formation and conformational adaptation of self-assembled monolayer of 2H- tetraphenylporphyrins (2H-TPPs) on metal surfaces, as well as their metalation processes in ultra-high vacuum (UHV), are reviewed.
Abstract: The formation and conformational adaptation of self-assembled monolayer of 2H- tetraphenylporphyrins (2H-TPPs) on metal surfaces, as well as their metalation processes in ultra-high vacuum (UHV), are reviewed. By means of XPS, NEXAFS and STM measurements we demonstrate that, after the annealing at 550 K, a temperature-induced chemical modification of 2H-TPP monolayer on Ag(111) occurs, resulting in the rotation of the phenyl rings parallel to the substrate plane. Moreover, independently of the conformation, we report three dierent methods to metalate 2H-TPP monolayers in UHV. Experimental evidence indicates that the presence of a metal atom in the TPP macrocycle influences both the conformation of the molecule and its adsorption distance.
8 citations
TL;DR: XPS results provide evidence of the iron coordination with TPP molecules on Fe/Si as well as on Fe3Si/Si, and UPS analysis evidenced the fine structure in the electronic spectra related to HOMO states below the Fermi level.
Abstract: Many recent studies have highlighted the possibility to tailor the physical and chemical properties of porphyrin at the molecular level to design novel catalysts, sensors and devices with applications in electronics, opto-electronics, and so forth. In the present work, we study the electronic properties of 2H-Tetraphenylporphyrin (2H-TPP) on iron (Fe) and iron silicide (Fe3Si) onto Si (100) substrate using X-ray and Ultraviolet photoelectron spectroscopy (XPS & UPS). The results revealed that the iron atom is coordinated by TPP molecules on Fe/Si as well as on Fe3Si/Si. XPS results provide evidence of the iron coordination with TPP molecules. The UPS analysis evidenced the fine structure in the electronic spectra related to HOMO states below the Fermi level.
2 citations
03 Jun 2013
TL;DR: In this paper, the morphological changes and the effect of milling time on Mg - x wt% FeTi (x = 2 and 5) nano composites were investigated by employing Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques.
Abstract: Nano composites were prepared by mechanical alloying in a Retsch planetary ball mill. The morphological changes and the effect of milling time on Mg - x wt% FeTi (x = 2 & 5) nano composites were investigated by employing Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. The results show that the crystallize size decreases with milling time while the micro-strain increases. SEM result also supports the XRD result and analysis.
1 citations