Femtosecond laser crystallization of amorphous Ge

Cataloged from PDF version of article.Ultrafast crystallization of amorphous germanium (a-Ge) in ambient has been studied. Plasma enhanced chemical vapor deposition grown a-Ge was irradiated with single femtosecond laser pulses of various durations with a range of fluences from below melting to above ablation threshold. Extensive use of Raman scattering has been employed to determine post solidification features aided by scanning electron microscopy and atomic force microscopy measurements. Linewidth of the Ge optic phonon at 300 cm(-1) as a function of laser fluence provides a signature for the crystallization of a-Ge. Various crystallization regimes including nanostructures in the form of nanospheres have been identified. (C) 2011 American Institute of Physics. [doi:10.1063/1.3601356

Probing ultrafast energy transfer between excitons and plasmons in the ultrastrong coupling regime

Cataloged from PDF version of article.We investigate ultrafast energy transfer between excitons and plasmons in ensembles of core-shell type nanoparticles consisting of metal core covered with a concentric thin J-aggregate (JA) shell. The high electric field localization by the Ag nanoprisms and the high oscillator strength of the JAs allow us to probe this interaction in the ultrastrong plasmon-exciton coupling regime. Linear and nonlinear optical properties of the coupled system have been measured using transient absorption spectroscopy revealing that the hybrid system shows half-plasmonic and half-excitonic properties. The tunability of the nanoprism plasmon resonance provides a flexible platform to study the dynamics of the hybrid state in a broad range of wavelengths. (C) 2014 AIP Publishing LLC

Crystallization of Ge in SiO2 matrix by femtosecond laser processing

Cataloged from PDF version of article.Germanium nanocrystals embedded in a siliconoxide matrix has been fabricated by single femtosecond laser pulse irradiation of germanium doped SiO2 thin films deposited with plasma enhanced chemical vapor deposition. SEM and AFM are used to analyze surface modification induced by laser irradiation. Crystallization of Ge in the oxide matrix is monitored with the optic phonon at 300 cm(-1) as a function of laser fluence. Both the position the linewidth of the phonon provides clear signature for crystallization of Ge. In PL experiments, strong luminescence around 600 nm has been observed. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3677829

Electrochemically tunable ultrafast optical response of graphene oxide

Cataloged from PDF version of article.We demonstrate reversible and irreversible changes in the ultrafast optical response of multilayer graphene oxide thin films upon electrical and optical stimulus. The reversible effects are due to electrochemical modification of graphene oxide, which allows tuning of the optical response by externally applied bias. Increasing the degree of reduction in graphene oxide causes excited state absorption to gradually switch to saturable absorption for shorter probe wavelengths. Spectral and temporal properties as well as the sign of the ultrafast response can be tuned either by changing the applied bias or exposing to high intensity femtosecond pulses. © 2011 American Institute of Physics

[μ-N,N′-Bis(3-meth­oxy-2-oxidobenzyl­idene)propane-1,3-diamine]trinitratocopper(II)terbium(III) acetone solvate

In the title complex, [CuTb(C19H20N2O4)(NO3)3]·CH3COCH3, the CuII atom is four-coordinated by two O atoms and two N atoms from the deprotonated Schiff base in a square-planar geometry, while the TbIII atom is ten-coordin­ated by four O atoms from the deprotonated Schiff base and six O atoms from three bidentate nitrate anions. The compound is isostructural with the previously reported GdIII analogue [Elmali & Elerman (2004 ▶). Z. Naturforsch. Teil B, 59, 535–540], which was described in the space group P1 with two formula units in the asymmetric unit. The crystal stucture is, in fact, centrosymmetric and is described here in the space group P with one formula unit in the asymmetric unit

Encapsulation of a zinc phthalocyanine derivative in self-assembled peptide nanofibers

Cataloged from PDF version of article.In this article, we demonstrate encapsulation of octakis(hexylthio) zinc phthalocyanine molecules by non-covalent supramolecular organization within self-assembled peptide nanofibers. Peptide nanofibers containing octakis(hexylthio) zinc phthalocyanine molecules were obtained via a straight-forward one-step self-assembly process under aqueous conditions. Nanofiber formation results in the encapsulation and organization of the phthalocyanine molecules, promoting ultrafast intermolecular energy transfer. The morphological, mechanical, spectroscopic and non-linear optical properties of phthalocyanine containing peptide nanofibers were characterized by TEM, SEM, oscillatory rheology, UV-Vis, fluorescence, ultrafast pump-probe and circular dichroism spectroscopy techniques. The ultrafast pump-probe experiments of octakis(hexylthio) zinc phthalocyanine molecules indicated pH controlled non-linear optical characteristics of the encapsulated molecules within self-assembled peptide nanofibers. This method can provide a versatile approach for bottom-up fabrication of supramolecular organic electronic devices. © 2012 The Royal Society of Chemistry

{μ-6,6′-Dimeth­oxy-2,2′-[propane-1,3-diyl­bis(nitrilo­methyl­idyne)]­diphenolato}­trinitratocopper(II)samarium(III) acetone solvate

In the title complex, [CuSm(C19H20N2O4)(NO3)3]·CH3CO-CH3, the CuII atom is four-coordinated in a square-planar geometry by two O atoms and two N atoms of the deprotonated Schiff base. The SmIII atom is ten-coordinate, chelated by three nitrate groups and linked to the four O atoms of the deprotonated Schiff base

{μ-6,6′-Dimeth­oxy-2,2-[propane-1,3-diylbis(nitrilo­methanylyl­idene)]diphenolato}trinitratocopper(II)dysprosium(III) methanol monosolvate

In the title heterodinuclear salen-type complex, [CuDy(C19H20N2O4)(NO3)3]·CH3OH, the copper(II) ion is tetra­coordinated by two imino N atoms [Cu—N = 1.961 (4) and 1.968 (4) Å] and two phenolate O atoms [Cu—O = 1.931 (3) and 1.938 (3) Å] in a planar geometry. The ten-coordin­ate DyIII ion is ligated by six O atoms of three nitrate groups and four O atoms from the ligand [Dy—O = 2.368 (3)–2.601 (3) Å]. In the crystal, complex mol­ecules and solvent mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds