Frenkel defect interactions at surfaces of irradiated alkali halides studied by non-contact atomic-force microscopy

Kołodziej, Jacek; Such, Bartosz; Czuba, P.; Piątkowski, P.; Struski, P.; Szymoński, Marek; Bennewitz, Roland; Schär, S.; Meyer, Ernst

doi:10.1016/s0039-6028(01)00936-0

Cited by 31 publications

(37 citation statements)

References 10 publications

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“…surface where halogen atoms are ejected out of the plane and alkali metal atoms aggregate into metallic clusters [15,[52][53][54][55]. Although this model suggests that electron induced desorption of alkali halide surfaces essentially leads to halogen atom removal, similar kinetics and desorption fluxes have been reported for halogen and alkali metal atoms [14,15,37,55].…”

Section: Discussionmentioning

confidence: 74%

Reaction kinetics of ultrathin NaCl films on Ag(001) upon electron irradiation

et al. 2017

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We report on an electron-induced modification of alkali halides in the ultrathin film regime. The reaction kinetics and products of the modifications are investigated in the case of NaCl films grown on Ag(001). Their structural and chemical modification upon irradiation with electrons of energy 52-60 eV and 3 keV is studied using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES), respectively. The irradiation effects on the film geometry and thickness (ranging from between two and five atomic layers) are examined using scanning tunneling microscopy (STM). We observe that Cl depletion follows different reaction kinetics, as compared to previous studies on NaCl thick films and bulk crystals. Na atoms produced from NaCl dissociation diffuse to bare areas of the Ag(001) surface, where they form Na-Ag superstructures that are known for the Na/Ag(001) system. The modification of the film is shown to proceed through two processes, which are interpreted as a fast disordering of the film with removal of NaCl from the island edges and a slow decrease of the structural order in the NaCl with formation of holes due to Cl depletion. The kinetics of the Na-Ag superstructure growth is explained by the limited diffusion on the irradiated surface, due to aggregation of disordered NaCl molecules at the substrate step edges.

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Section: Discussionmentioning

confidence: 74%

Reaction kinetics of ultrathin NaCl films on Ag(001) upon electron irradiation

et al. 2017

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“…The alkali atoms desorbed by the thermal desorption are from the topmost surface only. Although the source of halogen atoms desorbed by the thermal desorption is not the topmost surface, a halogen and alkali di-vacancy is left behind on the topmost surface by the recombination of an F * center with an alkali atom (the scenario mentioned in the Introduction) [8][9][10][11] . The desorption rates obtained from the number of atoms on the topmost surface and the number of incident electrons in a period correspond to the thermal desorption component independently of non-thermal desorption.…”

Section: (A)mentioning

confidence: 99%

“…By expanding the area of each pit or by increasing the number of pits, removal of theˆrst layer proceeds. Thus, the morphology of the surface develops as the irradiation ‰uence increases; roughly speaking, this behavior of the pits is repeated during the removal of several layers [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

Detection System for KeV Proton Beam Scattered from an ESD-surface with Monolayer Pits of Alkali Halide Crystal

2017

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To observe specular oscillations in ion-surface scattering originating from layer-by-layer desorption of an electron stimulated desorbed (ESD) surface, a 15 keV proton beam was impinged on the surface with an angle of incidence less than 1°. We prepared an experimental system to examine the scattering yields of re‰ecting protons by conveniently employing a ‰uorescent screen to view scattering yields (scattering patterns) and a commercial digital camera for yield measurements. Because the present energy of the proton beam was too low to illuminate the screen, a micro-channel plate was inserted in front of the screen. Measurements with electron irradiation show obvious damping specular oscillations; the widths of angular distributions of scattered protons simultaneously oscillated with increasing electron ‰uence. From the measured periods of the oscillations, the ESD rates of thermal desorption from KBr(001) at 1.5 keV electrons irradiation were obtained for sample temperatures.

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“…Using the AFM technique, it was for the first time possible to study not only what already left the surface but to examine the atomic structure of the crystal right after the desorption process without exposing it to the reactive ambient environment [11,17]. This atomistic approach to processes leading to surface modification allowed for establishing a consistent theoretical model describing both the particle emission from bombarded alkali halides, and the surface topography changes due to beam-induced electronic excitation/ionisation [9,18].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the defect-mediated desorption of alkali halide surfaces

Szymoński

Droba

Struski

2012

Low Temperature Physics

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Dynamic processes leading to desorption of Rb and I atoms from the RbI (100) surface co-irradiated with 1 keV electrons and visible light (with a wavelength corresponding to the F-center absorption band) have been studied by means of mass-selected time-of-flight (TOF) spectroscopy. Depending on the sample temperature, substantial enhancement of the desorption yield, as well as pronounced changes in the TOF spectra of the emitted atoms have been found. The TOF spectra of halogen atoms consist of two components: thermal (which can be fitted with Maxwellian distribution) and non-thermal one. The non-thermal peak is temperature-independent. There is no non-thermal component for alkali atoms. The comparison of TOF spectra for I atoms emitted from electron bombarded sample with and without simultaneous light irradiation indicates that the yield increase is caused by thermally desorbed atoms, while the non-thermal peak remains unchanged. Presented results confirm well the predictions of the theoretical model of desorption proposed earlier, known as the defect-mediated (F and H center) desorption of alkali halides.

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Frenkel defect interactions at surfaces of irradiated alkali halides studied by non-contact atomic-force microscopy

Cited by 31 publications

References 10 publications

Reaction kinetics of ultrathin NaCl films on Ag(001) upon electron irradiation

Reaction kinetics of ultrathin NaCl films on Ag(001) upon electron irradiation

Detection System for KeV Proton Beam Scattered from an ESD-surface with Monolayer Pits of Alkali Halide Crystal

Dynamics of the defect-mediated desorption of alkali halide surfaces

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