Nonmetal to Metal Transition and Ultrafast Charge Carrier Dynamics of Zn Clusters on p-Si(100) by fs-XUV Photoemission Spectroscopy

Vaida, Mihai E.; Marsh, Brett M.; Leone, Stephen R.

doi:10.1021/acs.nanolett.8b00700

Cited by 10 publications

(7 citation statements)

References 47 publications

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“…Our results demonstrate that signal variations of a few percent level can be resolved. It suggests that an absorption spectroscopy based X-ray streaking is suitable for the investigation of ultrafast dynamics in a variety of other fields [15][16][17] .…”

Section: Arxiv:181105917v1 [Cond-matmtrl-sci] 14 Nov 2018mentioning

confidence: 99%

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

et al. 2019

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Ultrafast dynamics are generally investigated using stroboscopic pump-probe measurements, which characterize the sample properties for a single, specific time delay. These measurements are then repeated for a series of discrete time delays to reconstruct the overall time trace of the process. As a consequence, this approach is limited to the investigation of fully reversible phenomena. We recently introduced an off-axis zone plate based X-ray streaking technique, which overcomes this limitation by sampling the relaxation dynamics with a single femtosecond X-ray pulse streaked over a picosecond long time window. In this article we show that the X-ray absorption cross section can be employed as the contrast mechanism in this novel technique. We show that changes of the absorption cross section on the percent level can be resolved with this method. To this end we measure the ultrafast magnetization dynamics in CoDy alloy films. Investigating different chemical compositions and infrared pump fluences, we demonstrate the routine applicability of this technique. Probing in transmission the average magnetization dynamics of the entire film, our experimental findings indicate that the demagnetization time is independent of the specific infrared laser pump fluence. These results pave the way for the investigation of irreversible phenomena in a wide variety of scientific areas.

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Section: Arxiv:181105917v1 [Cond-matmtrl-sci] 14 Nov 2018mentioning

confidence: 99%

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

et al. 2019

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“…High-order harmonic generation (HHG) based techniques are well established for studying ultrafast dynamics in atoms and molecules in the gas-phase, liquids, and solids using transient reflection, absorption, or photoelectron spectroscopy. 30,31 Small nanoparticles, however, have only very recently been probed with HHG based methods employing photoelectron spectroscopy 32 but have so far not been studied in absorption. We present a first investigation of nanoparticles with sub-monolayer surface coverage using HHG based static XUV absorption spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Ultrashort XUV pulse absorption spectroscopy of partially oxidized cobalt nanoparticles

Schiffmann

Toulson

Knez

et al. 2020

Journal of Applied Physics

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High-order harmonic generation (HHG) based transient extreme ultraviolet (XUV) absorption spectroscopy is an emerging technique to trace photoinduced charge carrier dynamics in condensed phase materials with femtosecond and even attosecond temporal resolution and elemental specificity. However, its application to nanoparticulate samples that are relevant, for example, for novel photocatalytic light harvesting concepts, has been limited. This is in part due to the challenge to produce residual-free samples on ultrathin, XUV-transparent substrates as well as a widespread understanding that sparsely distributed nanoparticles do not provide sufficient contrast for XUV absorption measurements. Here, we present static XUV absorption spectra of partially oxidized Co nanowire-structures with diameters of approximately 4.5 nm and lengths between 10 and 40 nm, recorded with an ultrashort pulse HHG light source. Nanoparticles are synthesized by the agglomeration of Co atoms inside superfluid helium droplets, followed bysurfacedepositionandoxidationinambient air.Themethodisuniquely suited for residual-free synthesis of transition metal nanowires and their deposition on ultrathin substrates. Analysis by high-resolution transmission electron microscopy reveals the formation of CoO nanowires with regions of unoxidized Co in their interior. The nanoparticle samples are investigated in an HHGdriven ultrafast XUV absorption setup. Despite the low surface coverage of only 23%, the recorded spectrum exhibits a distinct absorption feature at the Co M 2,3 (2p) edge near 60 eV with a peak height of about 40 mOD. The results support the feasibility of table-top ultrafast transient XUV absorption studies of photoinduced dynamics in transition metal oxide nanoparticles with sub-monolayer surface coverage.

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“…Gas-phase studies of zinc clusters that were generated in a magnetron sputter gas aggregation source indicated unusual electronic properties, which reveals the coexistence of insulating and metallic properties 11,12 . This has been a tremendous inspiration for synthetic groups that yearned for the isolation of Zn x aggregates with x > 3 in condensed phases.…”

mentioning

confidence: 99%

Stabilizing a metalloid {Zn12} unit within a polymetallide environment in [K2Zn20Bi16]6−

et al. 2020

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The access to molecules comprising direct Zn–Zn bonds has become very topical in recent years for various reasons. Low-valent organozinc compounds show remarkable reactivities, and larger Zn–Zn-bonded gas-phase species exhibit a very unusual coexistence of insulating and metallic properties. However, as Zn atoms do not show a high tendency to form clusters in condensed phases, synthetic approaches for generating purely inorganic metalloid Znx units under ambient conditions have been lacking so far. Here we show that the reaction of a highly reductive solid with the nominal composition K5Ga2Bi4 with ZnPh2 at room temperature yields the heterometallic cluster anion [K2Zn20Bi16]6–. A 24-atom polymetallide ring embeds a metalloid {Zn12} unit. Density functional theory calculations reveal multicenter bonding, an essentially zero-valent situation in the cluster center, and weak aromaticity. The heterometallic character, the notable electron-delocalization, and the uncommon nano-architecture points at a high potential for nano-heterocatalysis.

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Nonmetal to Metal Transition and Ultrafast Charge Carrier Dynamics of Zn Clusters on p-Si(100) by fs-XUV Photoemission Spectroscopy

Cited by 10 publications

References 47 publications

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

Ultrashort XUV pulse absorption spectroscopy of partially oxidized cobalt nanoparticles

Stabilizing a metalloid {Zn12} unit within a polymetallide environment in [K2Zn20Bi16]6−

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