Single-cycle terahertz (THz)-assisted atom probe tomography (APT) has emerged as a promising technique for triggering field evaporation under conditions that may reduce thermally activated contributions compared with conventional laser pulsing in conductive materials. While free carriers in metallic samples facilitate efficient THz near-field coupling at the specimen apex, nonmetallic materials like sol-gel silica lack this advantage, rendering positive THz pulses ineffective. However, negative THz pulses produce well-resolved mass spectra, which are compared with the mass spectra obtained with laser assisted APT( UV 343 nm and NIR 800 nm) to evaluate mass resolving power, signal-to-noise ratio and chemical composition. Moreover, we study the impact of the coating on the THz-APT results. Two metallization strategies are applied: (i) chromium (Cr) sputter coating via PECS and (ii) graphene encapsulation. Cr coating enables successful ion evaporation under positive THz pulses, improving mass resolution and reducing noise, while graphene encapsulation further enhances spectral clarity by sharpening peaks and reducing thermal tails. 3D reconstructions confirm effective deposition of both coatings over the tungsten-silica junction and reveal species segregation under positive THz pulses, highlighting the strong dependence of evaporation behavior on the applied field conditions.

Monazite (CePO4) is widely used in U-Th-Pb geochronology due to its reliable age determinations, although isotopic disturbances often require investigation at the nanoscale to better understand the mechanisms at play. Atom probe tomography (APT) offers unique capabilities for nanoscale chemical analysis and 3D atomic reconstruction but presents challenges for insulating materials such as CePO4, particularly due to oxygen loss during field evaporation. This study investigates the effects of laser wavelength, energy, metallic coatings, and detection device on mass spectrum optimization and compositional accuracy in synthetic CePO4 samples. Results show that shorter laser wavelengths (260 nm) enhance peak resolution, particularly when combined with advanced reflectron configurations, as demonstrated with the LEAP 6000 XR. Chromium coatings further improve thermal dissipation and reduce noise levels. However, compositional measurements reveal systematic underestimation of oxygen and overestimation of P and Ce, likely influenced by preferential low-field evaporation of certain elements. These findings highlight the need to carefully tune experimental parameters to mitigate quantification biases and enhance the reliability of APT analyses for geological materials.

Despite decades of research, how glass approaches equilibrium remains a subject of debate in the scientific community. This works aims at characterizing the impact of physical aging on the microstructure and relaxation properties in a magnesium-based metallic glass stored at room temperature for ten years. Calorimetric investigations and X-ray diffraction analyses ensured working on amorphous materials. Then, nanoindentation and atomic probe tomography were used to compare the response of an aged glass with its unaged homologue, in terms of relaxation and chemical structure. Nanoindentation revealed clear differences in terms of length scales associated to atomic rearrangements. The relaxation governed by one main mechanism in an unaged glass evolves towards the coexistence of two main mechanisms with distinct scales of motions. Finally, atom probe tomography mapped the nanoscale chemical and structural evolutions, accompanying the physical aging process. Physical aging manifests by a phase separation, reversible under rejuvenation, which is driven by a mechanism of enrichment/depletion involving the atoms with the highest diffusion coefficients.

Silicon dioxide is a suitable material to encapsulate proteins at room temperature so that they can be analyzed at the atomic level using laser-assisted atom probe tomography (La-APT). To achieve this goal, in this study we show that UV and deep-UV lasers can achieve a high success rate in La-APT of silica in terms of chemical resolution and three-dimensional image volume, with both lasers providing comparable results. Since the La-APT analyses are driven by photon absorption, in order to understand the mechanisms behind the enhanced absorption of UV light, we performed density functional theory calculations to model the electronic and optical properties of amorphous silica matrices generated using a Monte Carlo approach to structural optimization. In particular, we have investigated the role of various defects introduced during sample preparation, such as substitutional and interstitial carbon, sodium and gallium ions, and hydrogen. Our results show that the presence of defects increases the absorption of silica in the UV and deep-UV range and thus improves the La-APT capabilities of the material. However, due to the low density of free charge carriers resulting from the absorption of laser energy by defects, deviations from the nominal chemical composition and suboptimal chemical resolution may occur, potentially limiting the optimal acquisition of APT mass spectra.

This study investigates the emission of cations from silica samples by single-cycle THz pulses, focusing on the influence of pulse polarity. Negative THz pulses were found to efficiently trigger the evaporation of cations from nanoneedles in amorphous silica samples compared to positive pulses. Conversely, this dependence on pulse polarity is strongly reduced and reversed in samples with metallic behavior such as LaB6 and could not be found when multicycle pulses in different frequency ranges such as ultraviolet (UV) are used. First-principles simulations focus on silica under THz laser irradiation and show critical fields for ion evaporation of hydroxyl groups from Si(OH)4, which serves as a model precursor molecule for the amorphous solid matrix. To explain our experimental results, we propose a simplified theoretical model that determines the role of the polarity of the THz pulse by taking into account the differences in electron mobility between silica and semimetallic samples. The study explores the nonlinear microscopic mechanisms of atomic evaporation under external static and THz laser fields and clarifies the dynamics of THz-enhanced atom probe tomography and related applications.

We study the microscopic field evaporation behavior of hydrogen and related molecules in Atom Probe Tomography (APT) of pure Zr and a Zr hydride phase obtained by electrochemical charging. Our results show the presence of hydrogen ions H+, H2+, and H3+ for both systems, while hydride molecular ions ZrH2+ are found in the hydride phase. The distribution of the hydrogen ions H+, H2+ density map on the detector space of the charged sample reveals a crystallographic structure with symmetry close to a face-centered cubic (FCC) phase. The distribution of relative abundances of hydrogen ions and Zr2+ and hydride molecules also correlates with the crystallography, while a weaker correlation is found with the surface field distribution. In particular, the distribution of the detected species shows preferential formation for hydride molecules along selected crystallographic zone lines. These results are interpreted with the support of density functional theory (DFT) calculations and through the analysis of multiple detection events.

The demand for precise, high-energy Extreme Ultraviolet (EUV) sources is growing across scientific and industrial fields. Studies have demonstrated that bulk crystals driven by mid-infrared laser pulses can generate high-order harmonics with enhanced intensities, extended cut-off energies, and improved damage thresholds [1]. While high-energy OPCPA and OPA systems have been successfully utilized to achieve these results, their complexity highlights the need for simpler, more compact solutions [1]–[3].

Atom probe tomography data are composed of a list of coordinates of the reconstructed atoms in the probed volume. The elemental identity of each atom is derived from time-of-flight mass spectrometry, with no local chemical information readily available. In this study, we use a data processing technique referred to as field evaporation energy loss spectroscopy (FEELS), which analyzes the tails of mass peaks. FEELS was used to extract critical energetic parameters that are related to the activation energy for atoms to escape from the surface under intense electrostatic field and dependent of the path followed by the departing atoms. We focused our study on pure face-centered cubic metals. We demonstrate that the energetic parameters can be mapped in two-dimensional with nanometric resolution. A dependence on the considered crystallographic planes is observed, with sets of planes of low Miller indices showing a lower sensitivity to the field. The temperature is also an important parameter in particular for aluminum, which we attribute to an energetic transition between two paths of field evaporation between 25 and 60 K close to (002) pole. This paper shows that the information that can be retrieved from the measured energy loss of surface atoms is important both experimentally and theoretically.

We present findings on high harmonic generation (HHG) in solids utilizing a high-energy fiber laser system operating at 1550 nm. The driving laser source comprises an erbium-doped fiber chirped pulse amplifier (EDFA) combined with a post-compression stage employing a hollow-core photonic crystal fiber (HC-PCF) filled with noble gases. Nonlinear selfcompression in the HC-PCF enables the generation of ultrashort pulses with a duration of 50 fs and energy of 0.91 mu J at a repetition rate of 660 kHz. In a first step, harmonics up to H7 were observed when focusing the laser into small bandgap materials such as Zinc Oxide (ZnO). Subsequently, the system was enhanced to measure high harmonics in the extreme ultraviolet (XUV) range, with harmonics up to H25 observed using a large bandgap material, magnesium oxide (MgO). To the best of our knowledge, this represents the first solid-state HHG source driven by a high-energy few-cycle fiber laser in the telecom region.

The atomic-scale characteristics of stoichiometric lanthanum hexaboride (LaB6) material are investigated in this work using atom probe tomography (APT). The presence of a higher background level in the mass spectrum is attributed to continuous boron evaporation, causing preferential boron loss and affecting composition measurements. The measured composition in LaB6 exhibits inaccuracies influenced by the experimental conditions, particularly showing an excess of lanthanum (La). This enrichment is consistently linked to boron's tendency for continuous evaporation, leading to a higher fraction of multiple evaporation and detection events. Consequently, the susceptibility of boron to measurement errors is increased due to detector limitations. To address this issue, we propose a method of compositional correction based on pseudomultiple events and an abundance of isotopic pairs, which has been successfully applied to elements with two isotopes and has the potential for elements with multiple isotopes.

Terahertz (THz) radiation with low-energy photons (meV) is used in a wide range of applications, such as microscopy, sensing, and spectroscopy. However, recently, high amplitude THz pulses of MV/cm have been generated and used for electron emission and ion evaporation from field emitters, opening up the possibility of using high amplitude THz pulses for material imaging by THz-assisted atom probe tomography (APT). In this work, we compare the APT analyses of lanthanum hexaboride (LaB6) samples using a femtosecond near-infrared laser with those obtained using high-amplitude single-cycle THz pulses. The atomic-scale characterization of stoichiometric LaB6 is challenging in laser-assisted APT due to the detection losses of boron ions. Here, we show that the THz radiation reduces the emission of molecular ions and multiple detection events, and it increases the charge state of the emitted ions. All these effects result in an improvement in boron detection. Furthermore, the emission dynamics of boron and lanthanum ions differ in their evaporation times when using THz radiation. This work emphasizes the ability of high-amplitude, single-cycle THz pulses to well control material analysis in APT, leading to better results on chemical composition. It also paves the way for the use of this radiation for material manipulation.

This study investigates the emission of cations from silica samples by single-cycle THz pulses, focusing on the influence of pulse polarity. Negative THz pulses were found to efficiently trigger the evaporation of cations from nanoneedles in amorphous silica samples compared to positive pulses. Conversely, this dependence on pulse polarity could not be found in samples with metallic behaviour such as LaB_6 and when multi-cycle pulses in different frequency ranges such as ultraviolet (UV) are used. First-principles simulations focus on silica under THz laser irradiation and show critical fields for ion evaporation of hydroxyl groups from Si(OH)_4, which serves as a model precursor molecule for the amorphous solid matrix. To explain our experimental results, we propose a simplified theoretical model that determines the role of the polarity of the THz pulse by taking into account the differences in electron mobility between silica and semi-metallic samples. The study explores the nonlinear microscopic mechanisms of atomic evaporation under external static and THz laser fields and clarifies the dynamics of THz-enhanced APT and related applications.

We report on a high energy ultrafast fibre laser architecture designed for high harmonics generation in solids. The laser delivering 50 fs pulses with 2.12 µJ at 1550 nm has enabled the generation of harmonics up to harmonic H5 from a magnesium oxide (MgO) bulk sample. To the best of our knowledge this is the first solid-state HHG source driven by a µJ-class few-cycle fiber laser in the mid-IR region.

$\text{LaB}_{6}$ has been traditionally used as a thermionic electron source for electron microscopes, but has been hardly set to practical use as cold field emitter (CFE) [1–2]. The chemical inertness, the high conductivity and the dense structure make $\text{LaB}_{6}$ a good candidate as ultrafast electron source. In the present work, we study the emission properties of LaB 6 nano-tip fabricated by focused ion beam milling, under static electric field (static emission) and under femtosecond laser illumination (ultrafast emission), using a $2.25\mu \mathrm{m}$ laser at 13 MHz.