STM and XPS investigation of reaction of galena in air

Laajalehto, K.; Smart, Roger St. C.; Ralston, John; Suoninen, E.

doi:10.1016/0169-4332(93)90019-8

Cited by 99 publications

(31 citation statements)

References 16 publications

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“…The Pb 4f7/2 peak of nc-PbS before annealing in Fig. 1͑d͒ is comparable to the PbO peak binding energy values reported in the literature ͑138.5 eV͒, 16,17 acid via the uCOOH moiety. 18 Similarly, the Pb 4f7/2 peak value 136.8 eV measured in the annealed nc-PbS sample is in excellent agreement with the reported binding energy for Pb 4f/2 in PbS.…”

supporting

confidence: 73%

A PbS nanocrystal-C60 photovoltaic device for infrared light harvesting

Dissanayake

Hatton

Lutz

et al. 2007

Applied Physics Letters

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PbS nanocrystal ͑nc-PbS͒-C 60 photovoltaic devices are demonstrated, in which nc-PbS function as electron donors, showing infrared photosensitivity up to 1600 nm. Annealing nc-PbS is proved to remove capping oleic acid ligands, studied using x-ray photoelectron spectroscopy, significantly improving the short circuit current, open circuit voltage, and fill factor. The device performance is rationalized by quantum confinement in nc-PbS and energy level alignment at the heterojunction based on direct measurements of nc-PbS ionization potential using ultraviolet photoelectron spectroscopy.

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supporting

confidence: 73%

A PbS nanocrystal-C60 photovoltaic device for infrared light harvesting

Dissanayake

Hatton

Lutz

et al. 2007

Applied Physics Letters

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“…In a previous STM study of oxidation over much shorter time intervals (270 min), no preferential growth of oxidation products at steps was observed [16]. The growth appears homogeneous on the length scale of STM (nm) but in fact it is heterogeneous as well, on a micron scale.…”

Section: Discussionmentioning

confidence: 90%

“…In the carbon region of the spectrum, the additional carbon shoulder indicates that carbonate is also present [16,17,18], which may include bicarbonate and hydrated lead carbonate. As it is a weak shoulder on the tail of the main carbon peak it is difficult to quantify the coverage of this species.…”

Section: Discussionmentioning

confidence: 97%

“…XPS gives the chemical composition of the surface without spatial information, while STM gives highly resolved spatial information without reliable chemical information. From XPS it has been proposed that the surface species which form include metal deficient lead sulfide, sulfate [7,8,10], PbO [7,13], hydroxide [8,10], thiosulfate [14], sulfoxy species [15], carbonate [12,16,17,18] and polysulfide [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…There have been several X-ray Photoemission Spectroscopy (XPS) with both conventional and synchrotron light based excitation [6,7,8,9] and Scanning Tunneling Microscopy (STM) [10,11,12] studies as well as a very large number of electrochemical and other investigations. XPS gives the chemical composition of the surface without spatial information, while STM gives highly resolved spatial information without reliable chemical information.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Long-Term Oxidation Behaviour of Lead Sulfide Surfaces

Heun

Gregoratti

Barinov

et al. 2002

Nanoscale Spectroscopy and Its Applications to Semiconductor Research

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Abstract. We have applied nanospectroscopy to examine the surface oxidation of the prototypic mineral lead sulfide in two states: 'oxidised' (oxidised in air for one year); and 'clean' (cleaved in air and inserted into the vacuum system within about 10 minutes). The elements detected on the surfaces were Pb, S, O, Cl (a natural impurity) and C (adventitious or natural, carbonate). Images showed strong topographic contrast and weak chemical contrast for the oxygen 1s maps. Near defects such as steps, there is a higher concentration of oxygen, indicating a higher oxidation rate in this zone. From the O 1s and Pb 4f binding energies, it is concluded that the oxidation products present are Pb 3O4, PbCO3 and Pb(OH)2, while PbO, PbSO4 and PbO2 were excluded. Sulfur is present on the oxidised sample in two chemical states: one with the same binding energy as for the clean sample, due to the native PbS below the oxide film; and another of higher binding energy. The binding energy is assigned to S present as polysulfide and/or sulfur located at the oxide/sulfide interface. Spectra taken at different points on the surface show energy shifts up to about 0.5 eV, due to band bending and pinning of the Fermi level by defects or impurities.

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XPS study of fresh and oxidized (Pb,Ge)Te surfaces

Yashina

Kobeleva

Neudachina

et al. 2002

Surface & Interface Analysis

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The oxidation of (Pb,Ge)Te crystal surfaces at ambient temperature and humidity was studied by means of XPS in a time range from minutes to months. Vacuum-cleaved crystal was used for the experiment. It was found that Ge in a PbTe lattice occupies two different positions. At one of them, donor behaviour is revealed and the concentration of donor atoms increases at temperatures lower than those of the cubic-rhombohedral phase transition. It was found that oxidation takes place even after a few minutes of air exposure. Germanium atoms oxidize entirely to oxidation state +4, this being followed by slow oxidation of tellurium atoms from oxidation state −2 to +4. After a long air exposure, significant surface enrichment in Pb was observed.

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STM and XPS investigation of reaction of galena in air

Cited by 99 publications

References 16 publications

A PbS nanocrystal-C60 photovoltaic device for infrared light harvesting

A PbS nanocrystal-C60 photovoltaic device for infrared light harvesting

Long-Term Oxidation Behaviour of Lead Sulfide Surfaces

XPS study of fresh and oxidized (Pb,Ge)Te surfaces

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