Core-level lineshapes in photoemission from transition-metal intercalates of TaS<sub>2</sub>

Scarfe, J A; Hughes, H. P.

doi:10.1088/0953-8984/1/38/011

Cited by 12 publications

(2 citation statements)

References 16 publications

(14 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…52 Core-level line shapes of metallic TMDC's have been successfully modeled by taking into account the conduction electron screening response and the finite core-hole lifetime. [53][54][55][56] It is clear from Fig. 4 that, in addition to its 0.8-eV spin-orbit splitting, the Se 3d line shape is asymmetric with a characteristic ''metallic'' tail already for pure VSe 2 , and the line shape becomes even more asymmetric as the sample is intercalated with Na.…”

Section: B Core-level Screeningmentioning

confidence: 96%

Electronic structure of pure and alkali-metal-intercalatedVSe2

et al. 1998

View full text Add to dashboard Cite

The valence bands of the layered compound VSe 2 and the related intercalation compounds Na x VSe 2 , K x VSe 2 , and Cs x VSe 2 have been investigated by means of angle-resolved photoelectron spectroscopy, and compared to self-consistent linear augmented plane-wave ͑LAPW͒ band calculations. The intercalation compounds were prepared in situ by deposition of Na, K, and Cs on VSe 2 cleavage surfaces. The intercalation was monitored by core-level spectroscopy, and although K was found to intercalate more slowly than Na and Cs, estimated alkali concentrations of xϭ0.2-0.3 were reached for all three alkali metals. Additional depositions mainly seemed to increase the intercalation depth. Good agreement between LAPW calculations and valenceband spectra was found, in particular for the dispersion along the layers. Normal-emission spectra, obtained at different photon energies, indicated vanishing perpendicular dispersion, but in spectra measured under variation of the emission angle some band-edge signatures were seen, which suggests that some perpendicular dispersion remains, in accordance with the LAPW calculations. The lack of dispersion in the normal-emission spectra could be due to intercalation induced structural transformations, leading to stacking disorder. Also correlation effects may contribute. The rigid-band model is found inadequate, except as a crude approximation, for describing the changes during the initial phase of intercalation. It might be used to describe the continued intercalation, however, under condition that the intercalation modified bands are used. The need for studies that probe both electronic and crystallographic structure ͑including defects͒ is stressed. ͓S0163-1829͑98͒08536-1͔

show abstract

Section: B Core-level Screeningmentioning

confidence: 96%

Electronic structure of pure and alkali-metal-intercalatedVSe2

et al. 1998

View full text Add to dashboard Cite

show abstract

“…AE'»», the separation between the 2H peak and the mean of the 1T peaks, is 0.7~0.1 eV, similar to AEcDw, suggesting that the interlayer charge transfer is similar to the CDW amplitude. The effect of charge transfer on the JDOS and the peak asymmetries is less obvious; if the rigid band model is applicable, a shift of EF away from the peak of the lowest lying Ta d2 band DOS would occur in the 2H layers, reducing the asymmetry as for intercalates of 2H-TaS2 [13]. The effect for the 1T layers is unclear because of the CDW modification of the conduction band, and a proper determination of the asymmetries requires analysis using SHAPER.…”

mentioning

confidence: 99%

Site Specific Photohole Screening in a Charge Density Wave

Hughes

Scarfe

1995

Phys. Rev. Lett.

View full text Add to dashboard Cite

The line shapes of multiplet components of the complex x-ray photoemission spectra of the Ta 4f core levels in 1T-and 4Hb-TaS2 are shown to have different asymmetries associated with the charge density wave induced differences in the densities of states at distinct Ta sites which produce site specific local screening of the photohole. This underlines an important general effect in the interpretation of line shapes in x-ray photoemission. PACS numbers: 79.60.Jv, 79.60.Bm The screening of the photohole produced in x-ray core level photoemission (XPS) from a metal produces an inelastic tail to the low kinetic energy (KE) side of the XPS line. The resulting asymmetry depends on the excitations available to the screening carriers, i.e. , on the joint density of states (JDOS) near the Fermi energy (EF) [1]. A charge density wave (CDW) splits XPS lines because of the distinct chemical shifts for atomic sites with different local electron densities [2]: We show that the line shapes of the resulting multiplet components also differ because the local densities of states (LDOSs) are also modified by the CDW, and that detailed line shape fitting for several polytypes of TaS2 extracts parameters related to the electronic structure near specific atomic sites in the CDW supercell.TaS2 has hexagonal sheets of Ta atoms sandwiched between similar S sheets to form layers; the Ta coordination by the S atoms is either trigonal prismatic or octahedral.The 2H and 1T polytypes have unit cells with two trigonal prismatic and one octahedral layer, respectively, while 4Hb-TaS 2 has four, alternating between "1T"-and "2H"-like. Their electronic structures are similar; above the S 3p valence bands lies the Ta d band holding one electron per formula suit, and resulting in metallic properties. But in detail these d bands, and therefore their CDW behavior, differ; a quasicommensurate inplane~13 X~13 CDW exists for 1T-TaS~even at room temperature [3], at which 2H-TaS2 has no CDW. Below 180 K, 1T-TaSz adopts the 1T3 phase studied here, with a commensurate~13 &&~13 CDW with three distinct Ta sites -a, with one atom, and b and c with six atoms each -with different local charge densities. 4Hq-TaS2 shows behavior characteristic of both layer types; below 315 K it exhibits a~13 X~13 CDW associated with its 1T layers and below 22 K a 3 X 3 CDW characteristic of the 2H polytype [3,4]. Empirical arguments [2], and scanning tunneling microscopy (STM) [5], suggested a CDW amplitude in 1T3-TaS2 of a considerable fraction of an electron, though another [6] based on chemical shifts and a self-consistent calculation suggested 0.05 electron. A simple linear combination of atomic orbitals (LCAO) calculation for 1T3-TaS2, explicitly including the effects of A A2 P",(E) =, B(E -e") + 1 -,B(E),where A is the appropriate matrix element; convolving these for multiple excitations, and assuming A is small, gives the overall probability of energy loss E, P(E)~A~( e" ' -1) e ' 'exp g dt.-jL V P, V the CDW on the Ta d bands, shows that the LDOS is different for each...

show abstract

Surface Science Investigations of Intercalation Reactions with Layered Metal Dichalcogenides

Jaegermann

Tonti

2002

New Trends in Intercalation Compounds for Energy Storage

View full text Add to dashboard Cite

Core-level lineshapes in photoemission from transition-metal intercalates of TaS₂

Cited by 12 publications

References 16 publications

Electronic structure of pure and alkali-metal-intercalatedVSe2

Electronic structure of pure and alkali-metal-intercalatedVSe2

Site Specific Photohole Screening in a Charge Density Wave

Surface Science Investigations of Intercalation Reactions with Layered Metal Dichalcogenides

Contact Info

Product

Resources

About

Core-level lineshapes in photoemission from transition-metal intercalates of TaS2

Cited by 12 publications

References 16 publications

Electronic structure of pure and alkali-metal-intercalatedVSe2

Electronic structure of pure and alkali-metal-intercalatedVSe2

Site Specific Photohole Screening in a Charge Density Wave

Surface Science Investigations of Intercalation Reactions with Layered Metal Dichalcogenides

Contact Info

Product

Resources

About

Core-level lineshapes in photoemission from transition-metal intercalates of TaS₂