The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years

In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst the low-redshift BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor of 2.51 ± 0.71 from z ∼ 0.9 to z ∼ 0.1. Through this and other comparisons, we conclude that a combination of major merging (mainly wet or mixed) and in situ star formation are the main mechanisms which build stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a factor of ∼3, while their average Sérsic index increased by ∼0.45 from z ∼ 0.9 to z ∼ 0.1, also supporting a scenario involving major merging, though some adiabatic expansion is required. These observational results are compared to both models and simulations to further explore the implications on processes which shape and evolve BCGs/MMCGs over the past ∼7 Gyr

Formation of colloidal alloy semiconductor CdTeSe magic-size clusters at room temperature

Alloy magic-size clusters (MSCs) are difficult to synthesize, in part because so little is known about how they form. Here, the authors produce single-ensemble alloy CdTeSe MSCs at room temperature by mixing prenucleation-stage solutions of CdTe and CdSe, uncovering a formation pathway that may extend to the synthesis of other alloy MSCs

Study on the preparation of structured CuInS2 films by ion exchange processes

We examined the preparation of microstructured CuInS2 thin films in a sequential morphology transfer process. This low cost process is suitable for micro and nanostructuring of large areas. It starts from ZnO, which was electrodeposited as a film of vertically oriented columns. This was converted to ZnS by an anion exchange reaction in the gas phase with good reproduction of the outer morphlogy. Further conversion to nanostructured Cu2S, Ag2S, Bi2S3 and Sb2S3 by cation exchange in solution has already been proven [1, 2], but more difficulties arose for the conversion to In2S3. This is attributed to the more oxophilic character of the In3 ion, and to its destabilizing effect on organic reaction media at elevated temperature. A coarser structured sample of In2S3 was obtained, on which the final conversion step to CuInS2 proceeded readily with retention of this morpholog

A cyclic voltammetric study of mangano(II) undecatungstosilicate: An illustrative example of the reduction, protonation and disproportionation pathways of transition metal substituted heteropolytungstates in aqueous solution

Müller A, Dloczik L, Diemann E, Pope MT. A cyclic voltammetric study of mangano(II) undecatungstosilicate: An illustrative example of the reduction, protonation and disproportionation pathways of transition metal substituted heteropolytungstates in aqueous solution. INORGANICA CHIMICA ACTA. 1997;257(2):231-239.Mangano(II) undecatungstosilicate [(H2O)MnSiW11O39](6-) was studied by cyclic voltammetry in aqueous solution at various pH values. The pi-I-dependent wave patterns are influenced by additional processes and were further investigated by variation of scan rates, substance concentration and buffer concentration, focussing on the first 2-electron reduction. Polarographic data and results obtained from [(H2O)CoSiW11O39](6-) and [(H2O)(2)Mn-4(PW9O34)](10-) were included for comparison. A suitable pH range of 2.5-9 was determined from monitoring the decay of [(H2O)MnSiW11O39](6-) by electronic spectroscopy over a period of several weeks. Around pH 5, the cyclic voltammetric wave patterns appear more distorted than at higher and lower pH values. Conditions were specified under which the reoxidation scans exhibit two species with different degrees of protonation. The results were interpreted in terms of protonation and successive disproportionation of reduced species and suggest that a complex network of reversible reaction pathways takes place during the initial reduction processes of [(H2O)MnSiW11O39](6-) and related compounds in aqueous solution

Photovoltage study of charge injection from dye molecules into transparent hole and electron conductors

Transient and spectral photovoltage PV have been investigated for charge injection from a dye Ru dcbpyH2 2 NCS 2 into transparent hole CuSCN, CuI, CuAlO2 and electron TiO2, SnO2 F conductors. The PV signal rises to a maximum within 10 ns to 10 s, depending on the transparent hole or electron conductor and on the mechanism of charge separation. The efficiency of hole and electron injection is of the same order while the effective lifetimes of injected charge vary between 100 ns and 1 ms for the samples used. The injection thresholds range between 1.2 and 1.8 eV and depend sensitively on the material on which the dye is adsorbe

Photovoltage study of charge injection from dye molecules into transparent hole and electron conductors

Transient and spectral photovoltage (PV) have been investigated for charge injection from a dye [Ru(dcbpyH2)2(NCS)2] into transparent hole (CuSCN, CuI, CuAlO2) and electron ( TiO2, SnO2:F) conductors. The PV signal rises to a max. within 10 ns to 10 μs, depending on the transparent hole or electron conductor and on the mechanism of charge sepn. The efficiency of hole and electron injection is of the same order while the effective lifetimes of injected charge vary between several μs and 1 ms for the samples used. The thresholds for charge injection from the dye range between 1.6 and 1.8 eV depending on the material on which the dye is adsorbed