Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L<sub>2,3</sub>edge

Šiller, Lidija; Krishnamurthy, S.; Kjeldgaard, L.; Horrocks, Benjamin R.; Chao, Yimin; Houlton, and Andrew; Chakraborty, A.K.; Hunt, Michael

doi:10.1088/0953-8984/21/9/095005

Cited by 30 publications

(32 citation statements)

References 61 publications

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“…Silicon nanocrystals (Si‐NCs) and oxide‐embedded Si‐NC composites exhibit unique photoluminescence (PL) in the visible and near‐infrared (NIR) regions due to quantum confinement effect and/or surface effect. XAS and XEOL have been used to study the luminescence origin of Si‐NCs and functional Si‐NCs …”

Section: Si Nanostructures In Energy Applicationsmentioning

confidence: 99%

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

et al. 2014

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Carbon and silicon materials are two of the most important materials involved in the history of the science and technology development. In the last two decades, C and Si nanoscale materials, e.g., carbon nanotubes, graphene, and silicon nanowires, and quantum dots, have also emerged as the most interesting nanomaterials in nanoscience and nanotechnology for their myriad promising applications such as for electronics, sensors, biotechnology, etc. In particular, carbon and silicon nanostructures are being utilized in energy-related applications such as catalysis, batteries, solar cells, etc., with significant advances. Understanding of the nature of surface and electronic structures of nanostructures plays a key role in the development and improvement of energy conversion and storage nanosystems. Synchrotron soft X-ray absorption spectroscopy (XAS) and related techniques, such as X-ray emission spectroscopy (XES) and scanning transmission X-ray microscopy (STXM), show unique capability in revealing the surface and electronic structures of C and Si nanomaterials. In this review, XAS is demonstrated as a powerful technique for probing chemical bonding, the electronic structure, and the surface chemistry of carbon and silicon nanomaterials, which can greatly enhance the fundamental understanding and also applicability of these nanomaterials in energy applications. The focus is on the unique advantages of XAS as a complementary tool to conventional microscopy and spectroscopy for effectively providing chemical and structural information about carbon and silicon nanostructures. The employment of XAS for in situ, real-time study of property evolution of C and Si nanostructures to elucidate the mechanisms in energy conversion or storage processes is also discussed.

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Section: Si Nanostructures In Energy Applicationsmentioning

confidence: 99%

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

et al. 2014

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“…Since 1990, when Canham [1] found silicon nanostructures were able to emit visible light, interest in nanoscale silicon structures has risen sharply throughout the wider scientific community [2][3][4][5][6][7][8][9][10][11]. Owing to their ability to emit red light and lack of toxicity [12,13], silicon quantum dots (Si-QDs), are deemed to be one of the best candidates as bio-labels for applications in bio-imaging.…”

mentioning

confidence: 99%

Soft X‐ray induced oxidation on acrylic acid grafted luminescent silicon quantum dots in ultrahigh vacuum

Chao

Wang

Pietzsch

et al. 2011

Physica Status Solidi (a)

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Water soluble acrylic acid grafted luminescent silicon quantum dots (Si-QDs) were prepared by a simplified method. The resulting Si-QDs dissolved in water and showed stable strong luminescence with peaks at 436 and 604 nm. X-ray photoelectron spectroscopy (XPS) was employed to examine the surface electronic states after the synthesis. The co-existence of the Si2p and C1s core levels infers that the acrylic acid has been successfully grafted on the surface of silicon quantum dots. To fit the Si2p spectrum, four components were needed at 99.45, 100.28, 102.21 and 103.24 eV. The first component at 99.45 eV (I) was assigned to Si-Si within the silicon core of the Si-QDs. The second component at 100.28 eV (II) was from Si-C. The third at 102.21 eV (III) was a sub-oxide state and the fourth at 103.24 eV (IV) was from SiO 2 at Si-QDs surface. With an increase in exposure to soft X-ray photons, the intensity ratio of the two peaks within the Si2p region A and B increased from 0.5 to 1.4 while the peak A intensity decreased, and eventually a steady state was reached. This observation is explained in terms of photon-induced oxidation taking place within the surface dangling bonds. As the PL profile for Si-QDs is influenced by the degree of oxidation within the nanocrystal structure, the inducement of oxidation by soft X-rays will play a role in the range of potential applications where such materials could be used -especially within biomedical labelling.

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“…The degree of oxidation listed here is a qualitative estimation based upon the structure and chemical makeup of the nanoparticles studied in the work presented here. While it is true that the degree of surface oxidation of silicon nanostructures will play a role in the electronic density of states and consequently the photoluminescence profile,31, 32 such studies are not presented here and are thus a course for future research upon PAAc capped SiNPs.…”

Section: Resultsmentioning

confidence: 99%

Uptake and Toxicity Studies of Poly‐Acrylic Acid Functionalized Silicon Nanoparticles in Cultured Mammalian Cells

Wang

Bao

Zhang

et al. 2012

Adv Healthcare Materials

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Poly‐acrylic acid (PAAc) terminated silicon nanoparticles (SiNPs) have been synthesized and employed as a synchronous fluorescent signal indicator in a series of cultured mammalian cells: HHL5, HepG2 and 3T3‐L1. Their biological effects on cell growth and proliferation in both human and mouse cell lines have been studied. There was no evidence of in vitro cytotoxity in the cells exposed to PAAc terminated SiNPS when assessed by cell morphology, cell proliferation and viability, and DNA damage assays. The uptake of the nanocrystals by both HepG2 and 3T3‐L1 cells was investigated by confocal microscopy and flow cytometry, which showed a clear time‐dependence at higher concentrations. Reconstructed 3‐D confocal microscope images exhibited that the PAAc‐SiNPs were evenly distributed throughout the cytosol rather than attached to outer membrane. This study provides fundamental evidence for the safe application and further modification of silicon nanoparticles, which could broaden their application as cell markers in living systems and in micelle encapsulated drug delivery systems.

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Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L_2,3edge

Cited by 30 publications

References 61 publications

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

Soft X‐ray induced oxidation on acrylic acid grafted luminescent silicon quantum dots in ultrahigh vacuum

Uptake and Toxicity Studies of Poly‐Acrylic Acid Functionalized Silicon Nanoparticles in Cultured Mammalian Cells

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Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L2,3edge

Cited by 30 publications

References 61 publications

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

Synchrotron Soft X‐ray Absorption Spectroscopy Study of Carbon and Silicon Nanostructures for Energy Applications

Soft X‐ray induced oxidation on acrylic acid grafted luminescent silicon quantum dots in ultrahigh vacuum

Uptake and Toxicity Studies of Poly‐Acrylic Acid Functionalized Silicon Nanoparticles in Cultured Mammalian Cells

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Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L_2,3edge