Synthesis and optical properties of quantum-sized metal sulfide particles in aqueous solution

Nedelijkovic, J. M.; Patel, Ramesh C.; Kaufman, Phillip B.; Joyce-Pruden, C.; O'Leary, N

doi:10.1021/ed070p342

Cited by 57 publications

(40 citation statements)

References 6 publications

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“…The broad shoulder near 264 nm is similar to the shoulder at 264 nm observed by Sooklal et al (1996) who used a much higher concentration (0.2 mM each) of reactants without the use of thiols and indicated that the ZnS species in solution are molecular clusters. These data in Figure 1 are consistent with the quantum confinement effect (Nedeljkovic et al, 1993;Sooklal et al, 1996) and it is possible to calculate the maximum size of the clusters in solution based on the absorption peaks at 200, 230, 264 and 290 nm. The maximum diameter of the particles is calculated to be 1.6, 2.0, 2.4 and 2.8 nm respectively for the above wavelengths.…”

Section: Uv-vis Spectroscopy Size Fractionation and Anion Chromatogrsupporting

confidence: 80%

“…For the FeS system, ferredoxins containing thiols attached to Fe-S clusters are well known (e.g., Huheey et al, 1993). The preparation of other metal-sulfide clusters (e.g., ZnS, CuS, CdS and PbS) has been performed in laboratory studies (Herron et al, 1990;Kortan et al, 1990;Murphy, 1996;Nedeljkovic et al, 1993;Silvester et al, 1991;Vossmeyer et al, 1995;Løver et al, 1997). In these studies, the ion activity product, IAP, would exceed the solubility constant for the bulk metal sulfide, and to prevent precipitation, an organic protective agent (which terminates polymerization or condensation) such as thiols was added to interact with the clusters -sometimes in nonaqueous solvents.…”

Section: +mentioning

confidence: 99%

See 1 more Smart Citation

Erratum

2005

J Nanopart Res

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Aqueous clusters of FeS, ZnS and CuS constitute a major fraction of the dissolved metal load in anoxic oceanic, sedimentary, freshwater and deep ocean vent environments. Their ubiquity explains how metals are transported in anoxic environmental systems. Thermodynamic and kinetic considerations show that they have high stability in oxic aqueous environments, and are also a significant fraction of the total metal load in oxic river waters. Molecular modeling indicates that the clusters are very similar to the basic structural elements of the first condensed phase forming from aqueous solutions in the Fe-S, Zn-S and Cu-S systems. The structure of the first condensed phase is determined by the structure of the cluster in solution. This provides an alternative explanation of Ostwald's Rule, where the most soluble, metastable phases form before the stable phases. For example, in the case of FeS, we showed that the first condensed phase is nanoparticulate, metastable mackinawite with a particle size of 2 nm consisting of about 150 FeS subunits, representing the end of a continuum between aqueous FeS clusters and condensed material. These metal sulfide clusters and nanoparticles are significant in biogeochemistry. Metal sulfide clusters reduce sulfide and metal toxicity and help drive ecology. FeS cluster formation drives vent ecology and AgS cluster formation detoxifies Ag in Daphnia magna neonates. We also note a new reaction between FeS and DNA and discuss the potential role of FeS clusters in denaturing DNA.

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Section: Uv-vis Spectroscopy Size Fractionation and Anion Chromatogrsupporting

confidence: 80%

Section: +mentioning

confidence: 99%

Erratum

2005

J Nanopart Res

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“…This finding is in good agreement with the results of other authors using CBD prepared CdS films, and is usually ascribed to quantum size effects. 13,14 According to Nedeljkovic et al 15 the shift of E G corresponds to a mean-crystallite diameter of 7 nm. After the preparation of the CdS layers they were covered with a 200 nm thick tungsten oxide film which was thermally evaporated at a pressure of 10 Ϫ5 mbar from WO 3 pellets.…”

Section: ͓S0003-6951͑96͒01420-9͔mentioning

confidence: 99%

Photochromic coloration of WO3 with visible light

Bechinger

Wirth

Leiderer

1996

Applied Physics Letters

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Thin amorphous films of tungsten oxide (WO 3 ) are well known to change their optical absorption behavior upon light exposure, usually referred to as photochromic effect. Since the formation of color centers is closely related to the optical creation of electron-hole pairs the sensitivity of the photochromic effect in WO 3 is limited to energies above its band-gap energy of 3.25 eV, corresponding to the near-ultraviolet range. We will demonstrate that in case of a thin cadmium sulfide ͑CdS͒ layer underneath the tungsten oxide film the sensitivity of photochromism is shifted into the visible range. This result is interpreted in terms of charge carrier injection from the CdS into the WO 3 . Apart from a more detailed understanding of the photochromic effect this may have also relevance for technical applications. © 1996 American Institute of Physics. ͓S0003-6951͑96͒01420-9͔Due to the high potential of large area optical devices capable to be switched between a transparent and a strong absorptive state there is a large research activity within the last two decades regarding transition metal oxides. 1-3 One of the most promising candidates is tungsten oxide, often discussed in the context of ''smart windows'' in order to control the solar input of buildings or with respect to large area displays. 2,4 For most of these purposes the so-called electrochromic effect is used, where coloration and bleaching of tungsten oxide is caused by an electrochemical reaction. Much less attention has been paid so far to the light-induced coloration of WO 3 , i.e., photochromism, where an identical absorption band is formed upon irradiating bare tungsten oxide thin films with light. 1,5 Taking into account that the photochromic coloration can be made completely reversible by exposing the sample to oxygen gas, 6 the basic requirements for technical applications like erasable optical storage devices are met by the photochromic effect. However, since the formation of color centers in WO 3 requires irradiation in the near-ultraviolet range 1,6 where no compact light sources such as laser diodes are available at the moment, this may impede the development of integrated storage devices based on WO 3 considerably.In this letter we will demonstrate that the spectral sensitivity of photochromism in tungsten oxide can be shifted from the near-UV into the visible range by the use of a thin cadmium sulfide interlayer between the substrate and the WO 3 film. In addition to a more detailed understanding of the coloration mechanism, this result may also have relevance for the above-mentioned applications.It has already been demonstrated that the photochromic effect in tungsten oxide is intimately connected to optically excited electron (e Ϫ ) hole ͑h ϩ ) pairs which can decompose water being incorporated in WO 3 to a considerable amount. 6 The light-induced decomposition of H 2 O can be written as: 7,8 H 2 Oϩ2h ϩ ⇔Oϩ2H ϩ , ͑1͒which describes the creation of protons (H ϩ ) and metastable oxygen radicals ͑O͒. The protons together with the optically e...

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“…A derivation of this equation is presented elsewhere [43], [44]. The band gap of nanoparticles can be calculated using the cutoff wavelength obtained from the absorbance spectrum of a TiO 2 nanoparticles.…”

Section: Close Packedmentioning

confidence: 99%