Papers by Erika Giangrisostomi
Proceedings of SPIE, May 5, 2011
Applied Physics Letters, Apr 26, 2021
Tin is a suitable element for inclusion in extreme ultraviolet photoresists because of its relati... more Tin is a suitable element for inclusion in extreme ultraviolet photoresists because of its relatively high-absorption cross section at 92 eV. The electrons emitted after photon absorption are expected to generate secondary electrons in the solid film. In this way, several pathways lead to reactive species that cause a solubility switch. Here, we report the photoelectron spectra of tin oxo cage photoresists over the photon energy range 60-150 eV, and the relative yields of photoelectrons from the valence band of the resist, from the Sn 4d orbitals, and of inelastically scattered electrons. The experimental excitation spectra differ considerably from those predicted by commonly used database cross section values, and from the combined computed subshell spectra: the maximum efficiency of ionization of Sn 4d both in the photoresists and in Sn metal occurs near the industrially relevant EUV wavelength of 13.5 nm.
New Journal of Physics, Jul 1, 2019
Pump-probe photoelectron spectroscopy is a versatile tool to investigate the dynamics of transien... more Pump-probe photoelectron spectroscopy is a versatile tool to investigate the dynamics of transient states of excited matter. Vacuum space-charge effects can mask these dynamics and complicate the interpretation of electron spectra. Here we report on space-charge effects in Au 4f photoemission from a polycrystalline gold surface, excited with moderately intense 90 ps (FWHM) soft X-ray probe pulses, under the influence of the Coulomb forces exerted by a pump electron cloud, which was produced by intense 40 fs laser pulses. The experimentally observed kinetic energy shift and spectral broadening of the Au 4f lines, measured with highly-efficient time-of-flight spectroscopy, are in good agreement with simulations utilizing a mean field model of the electrostatic pump electron potential. This confirms that the line broadening is predominantly caused by variations in the takeoff time of the probe electrons without appreciable influence of local scattering events. Our findings might be of general interest for pump-probe photoelectron spectroscopy with picosecondpulse-length sources.
Journal of the American Chemical Society, Feb 28, 2019
High spin (S = 1) organic diradicals may offer enhanced properties with respect to several emergi... more High spin (S = 1) organic diradicals may offer enhanced properties with respect to several emerging technologies, but typically exhibit low singlet triplet energy gaps and possess limited thermal stability. We report triplet ground state diradical 2 with a large singlet-triplet energy gap, ΔE ST ≥ 1.7 kcal mol −1 , leading to nearly exclusive population of triplet ground state at room temperature, and good thermal stability with onset of decomposition at ~160 °C under inert atmosphere. Magnetic properties of 2 and the previously prepared diradical 1 are characterized by SQUID magnetometry of polycrystalline powders, in polystyrene glass, and in other matrices. Polycrystalline diradical 2 forms a novel one-dimensional (1D) spin-1 (S = 1) chain of organic radicals with intrachain antiferromagnetic coupling of J′/k = −14 K, which is associated with the N•••N and N•••O intermolecular contacts. The intrachain antiferromagnetic coupling in 2 is by far strongest among all studied 1D S = 1 chains of organic radicals, which also makes 1D S = 1 chains *
ACS Applied Materials & Interfaces, Jun 15, 2023
Molecules, Dec 13, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Chemistry: A European Journal, 2018
We have investigated the effect of intermolecular H- bonding interactions on the local electronic... more We have investigated the effect of intermolecular H- bonding interactions on the local electronic structure of N- functionalities, amino group and pyridine-like N, which are characteristic of a new ...
Advanced Materials, Apr 1, 2021
In article number 2006957, Nomi L. A. N. Sorgenfrei and co-workers demonstrate that a weak optica... more In article number 2006957, Nomi L. A. N. Sorgenfrei and co-workers demonstrate that a weak optical excitation creates electrons in the conduction band of p-doped semiconducting molybdenum disulfide, which travel toward the surface layer. They accumulate in the top layer and concomitantly drive it from the semiconducting toward the metallic phase. The selectivity of synchrotron time-resolved electron spectroscopy traces this effect. This surface modification influences the properties and functionality of MoS 2. Frontispiece Art: Martin Künsting.
Scientific Reports, Mar 25, 2021
The layered dichalcogenide MoS 2 is relevant for electrochemical Li adsorption/intercalation, in ... more The layered dichalcogenide MoS 2 is relevant for electrochemical Li adsorption/intercalation, in the course of which the material undergoes a concomitant structural phase transition from semiconducting 2H-MoS 2 to metallic 1T-Li x MoS 2. With the core hole clock approach at the S L 1 X-ray absorption edge we quantify the ultrafast directional charge transfer of excited S3p electrons in-plane () and out-of-plane (⊥) for 2H-MoS 2 as τ 2H,� = 0.38 ± 0.08 fs and τ 2H,⊥ = 0.33 ± 0.06 fs and for 1T-Li x MoS 2 as τ 1T,� = 0.32 ± 0.12 fs and τ 1T,⊥ = 0.09 ± 0.07 fs. The isotropic charge delocalization of S3p electrons in the semiconducting 2H phase within the S-Mo-S sheets is assigned to the specific symmetry of the Mo-S bonding arrangement. Formation of 1T-Li x MoS 2 by lithiation accelerates the in-plane charge transfer by a factor of ∼ 1.2 due to electron injection to the Mo-S covalent bonds and concomitant structural repositioning of S atoms within the S-Mo-S sheets. For excitation into out-ofplane orbitals, an accelerated charge transfer by a factor of ∼ 3.7 upon lithiation occurs due to S-Li coupling.
Scientific Reports, Dec 31, 2020
The photon flux was adjusted using the filters available at the beamline to avoid radiation damag... more The photon flux was adjusted using the filters available at the beamline to avoid radiation damage of the samples. The samples were measured with a pressure of about 10 −8 mbar in the analysis chamber. A high-resolution hemispherical electron analyser (SCIENTA EW4000) was used for detection of electrons with a pass energy of 200 eV and an analyser slit of 0.3 mm. Measurements of the Fermi edge and Au 4f. levels of a gold foil mounted on the manipulator were used for energy calibration for PES and HAXPES measurements.
Chemistry of Materials, Jan 27, 2021
We have demonstrated that it is possible to evaporate diradicals in a controlled environment obta... more We have demonstrated that it is possible to evaporate diradicals in a controlled environment obtaining thin films in which the diradical character is preserved. However, evaporation represents a challenge. The presence of two radical sites makes the molecules more reactive, even in case of very stable single radicals. We have explored the parameters that play a role in this phenomenon. Bulk formation thermodynamics and delocalisation of the unpaired electrons play the major role. The higher the formation energies of the crystal, the more difficult is the evaporation of intact radicals. The larger the delocalization, the more stable is the film exposed
Advanced Materials, Mar 4, 2021
Dichalcogenides MX 2 (transition metal M and chalcogen X) as van der Waals coupled, layered, quas... more Dichalcogenides MX 2 (transition metal M and chalcogen X) as van der Waals coupled, layered, quasi 2D materials allow for tailored electronic properties and are thus of high relevance for devices, gas sensors, and chemical processes. [1] Underlying is the existence of multiple phases and stacking orders and the ability to be doped and to intercalate as a host material. [2] The dichalcogenide molybdenite (MoS 2) occurs as a thermodynamically stable bulk crystal with an indirect bandgap of 1.2 to 1.3 eV. [3-5] Its crystal structure consists of stacked S-Mo-S sheets with a trigonal prismatic symmetry of A-B-A stacking, where the sulfur atoms in the top and bottom S-planes occupy equivalent vertical positions. [3] The S-Mo-S sheets have 6.5 Å distance with respect to each other. [6] Going from indirect-bandgap bulk 2H-MoS 2 toward a single layer, the bandgap gradually widens, reaching for monolayer MoS 2 a direct bandgap of 1.9 eV. [5] The semiconducting 2H-MoS 2 phase supports
Chemical Science, 2020
We have investigated the radical functionalization of gold surfaces with a derivative of the perc... more We have investigated the radical functionalization of gold surfaces with a derivative of the perchlorotriphenylmethyl (PTM) radical using two methods: by chemisorption from the radical solution and by on-surface chemical derivation from a precursor. We have investigated the obtained selfassembled monolayers by photon-energy dependent X-ray photoelectron spectroscopy. Our results show that the molecules were successfully anchored on the surfaces. We have used a robust method that can be applied to a variety of materials to assess the stability of the functionalized interface. The monolayers are characterized by air and X-ray beam stability unprecedented for films of organic radicals. Over very long X-ray beam exposure we observed a dynamic nature of the radical-Au complex. The results clearly indicate that (mono)layers of PTM radical derivatives have the necessary stability to withstand device applications.
Journal of Electron Spectroscopy and Related Phenomena, Apr 1, 2018
The simultaneous detection of energy, momentum and temporal information in electron spectroscopy ... more The simultaneous detection of energy, momentum and temporal information in electron spectroscopy is the key aspect to enhance the detection efficiency in order to broaden the range of scientific applications. Employing a novel 60 • wide angle acceptance lens system, based on an additional accelerating electron optical element, leads to a significant enhancement in transmission over the previously employed 30 • electron lenses. Due to the performance gain, optimized capabilities for time resolved electron spectroscopy and other high transmission applications with pulsed ionizing radiation have been obtained. The energy resolution and transmission have been determined experimentally utilizing BESSY II as a photon source. Four different and complementary lens modes have been characterized.
arXiv (Cornell University), Nov 3, 2020
Organic-inorganic halide perovskites have been intensively re-investigated due to their applicati... more Organic-inorganic halide perovskites have been intensively re-investigated due to their applications, yet the opto-electronic function of the organic cation remains unclear. Through organic-selective resonant Auger electron spectroscopy measurements on well-defined single crystal surfaces, we find evidence for electronic coupling in the unoccupied states between the organic and inorganic sub-lattices of the prototypical hybrid perovskite, which is contrary to the notion based on previous studies that the organic cation is electronically inert. The coupling is relevant for electron dynamics in the material and for understanding opto-electronic functionality. GJM thanks Lucinda Man for the discussion on energy coupling between cubo-octahedron and the octahedron sub-structures. GJM thanks Sigurd Wagner (Princeton) for the suggestion to investigate the hot carrier cooling mechanisms in lead halide perovskites, and Jeff Schwartz (Princeton) for the discussion on methylammonium de-protonation. GJM thanks Luis K. Ono (OIST) and Yabing Qi (OIST) for their suggestions on how to cleave HaP crystals in-vacuum.
Nanoscale, 2022
Radio frequency sputtering by argon ions on a target consisting of tungsten disulphide can create... more Radio frequency sputtering by argon ions on a target consisting of tungsten disulphide can create a single layer of the compound on a 4′′ Si-wafer with one W atom per two S atoms when including hydrogen sulphide in the sputtering atmosphere.
New Journal of Physics, Nov 7, 2012
Physical Review B, 2016
Solid Si under intense femtosecond irradiation is investigated over a wide range of fluences belo... more Solid Si under intense femtosecond irradiation is investigated over a wide range of fluences below the melting transition by supercontinuum light (400-800 nm) transient reflectivity. By solving a system of time-dependent equations, the fast and slow components of the energy and carriers diffusion can be disentangled from the reflectivity data, providing considerable insight into the nonequilibrium phase-change dynamics. The study of the fluence values immediately preceding the dramatic melting transition can be useful for discriminating between the thermal and electronic origins of the disordering of the structure by looking at the modification of the solid-state properties of the Si surface.
Physical Review B, 2017
We report a time-resolved study of the relaxation dynamics of Al films excited by ultrashort inte... more We report a time-resolved study of the relaxation dynamics of Al films excited by ultrashort intense free-electron laser (FEL) extreme ultraviolet pulses. The system response was measured through a pump-probe detection scheme, in which an intense FEL pulse tuned around the Al L 2,3 edge (72.5 eV) acted as the pump, while a time-delayed ultrafast pulse probed the near-infrared (NIR) reflectivity of the Al film. Remarkably, following the intense FEL excitation, the reflectivity of the film exhibited no detectable variation for hundreds of femtoseconds. Following this latency time, sizable reflectivity changes were observed. Exploiting recent theoretical calculations of the EUV-excited electron dynamics [N. Medvedev et al., Phys. Rev. Lett. 107, 165003 (2011)], the delayed NIR-reflectivity evolution is interpreted invoking the formation of very-long-living nonthermal hot electron distributions in Al after exposure to intense EUV pulses. Our data represent the first evidence in the time domain of such an intriguing behavior.
arXiv: Materials Science, 2020
Hybrid perovskite materials have been intensively re-investigated due to their opto-electronic ap... more Hybrid perovskite materials have been intensively re-investigated due to their opto-electronic applications. Photoelectron spectroscopy measurements have been performed on polycrystalline films, yet the function of the organic cation remains unclear. We circumvent experimental limitations through measurements on well-defined single crystal surfaces and find evidence for electronic coupling between the organic and inorganic sub-lattices of the prototypical hybrid perovskite, which is contrary to the notion based on previous studies that the organic cation is electronically inert. The coupling may be relevant for understanding carrier dynamics in this class of materials.
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Papers by Erika Giangrisostomi