9616 research outputs found
Sort by
Optical control of a metastable phase in the charge-density-wave Mott insulator ▫▫ investigated using time-resolved ARPES
No full textLight-induced metastable phases are exotic, long-lived out-of-equilibrium states of matter. Optical control offers a powerful approach to engineering these phases, enabling dynamic tuning of their electronic and structural properties. Using time- and angle-resolved photoemission spectroscopy, we investigate the emergence of a metastable phase induced by a strong infrared pump in the charge-density-wave (CDW)-Mott insulator 1T-TaS2. Furthermore, we demonstrate how its properties can be optically manipulated by varying the photoexcitation strength. A long-lived stabilization of the renormalized electronic band structure serves as a signature of the metastable phase. It displays a relaxed periodic lattice distortion (PLD) and primarily lattice-driven dynamics. The emergence of a new dispersive band in the vicinity of the Hubbard bands reveals the formation of a novel band structure unique to the metastable phase. Our pump-fluence-dependent studies reveal a threshold (incident) fluence ▫▫ ~ 1.3 mJ/▫▫ for inducing the metastable phase, above which the band renormalization continuously evolves with increasing fluence. For ▫▫ 3.4 mJ/▫▫, stronger photoexcitation progressively drives the phase to higher energies, accompanied by a more relaxed PLD and reduced CDW amplitude. The properties of the metastable phase are strongly influenced by the transient dynamics at each fluence, and the associated fast timescales suggest that the intrinsic CDW amplitude mode remains unaffected by optical manipulation. These findings highlight the potential of optical control in tuning the properties of metastable phases in quantum materials, offering new insights into the manipulation of CDW systems and paving the way for future investigations in non-equilibrium phase engineering
Identification of volatile organic compounds as natural antifungal agents against Botrytis cinerea in grape-based systems
No full textBotrytis cinerea Pers., the causal agent of grey mould, causes major economic losses in viticulture by reducing grape and wine quality and yield. Antagonistic yeasts that release bioactive volatile organic compounds (VOCs) represent a sustainable alternative to synthetic fungicides. Here, VOCs produced by Pichia guilliermondii strain ZIM624 were identified and assessed for antifungal activity against B. cinerea. 65 VOCs—including higher alcohols, volatile phenols, esters, and terpenes—were detected using two newly developed and validated analytical methods combining automated headspace solid-phase microextraction with gas chromatography–mass spectrometry. A total of 13 VOCs were selected for the bioassays. Fumigation assays demonstrated that terpenes (citronellol, geraniol, nerol, α-terpineol, and linalool) were the most effective inhibitors of B. cinerea mycelial growth (EC50 = 6.3–33.9 μL/L). Strong inhibition was also observed for 4-vinylphenol and isoamyl acetate. In vivo assays confirmed that exposing infected grape berries to P. guilliermondii VOCs significantly reduced grey mould incidence. These results highlight the potential of P. guilliermondii ZIM624 volatiles as natural biofumigants for the eco-friendly management of B. cinerea in grapes. Future research should focus on optimising VOC production, evaluating efficacy under field conditions, and developing formulations for practical application in vineyards and post-harvest storage. Additionally, investigating potential synergistic effects of VOC combinations could lead to more effective biocontrol strategies
Irradiation-induced point defects in optical fibers investigated by cathodoluminescence microscopy and spectroscopy
No full text
Chemical instability and formation of new phases at the interface between metallic thin films and ▫▫ topological insulator
No full text
Investigation of thermal properties of cement Sorel by photothermal deflection technique
No full textPhotothermal deflection PTD is a non destructive Technique. PTD is based on the photothermal
phenomenon, in which a modulated incident light on the specimen is transformed into heat and
detected as a tension by using a position photodetecor linked to a lock in amplifier. The signal depends
directly on the thermal properties (Thermal conductivity, thermal diffusivity) of the specimen [1]. In
this work we investigated the thermal property of cement Sorel (CS). Nowadays, the development of
composite construction materials with low thermal properties will be an interesting alternative that
would solve energy concerns. In this context, we investigate the effect of replacing Sorel cement with
polymer PVAc [2]. The thermal properties are measured using the Photothermal Deflection Technique
(PTD) by comparing the experimental curves of normalized amplitude and phase of photothermal
signal versus square root modulation frequency to the corresponding theoretical ones. The
experimental investigation revealed that the addition of the PVAc reduces the Thermal conductivity
and thermal diffusivity of the cement and yield a lightweight. The thermal insulating effect of PVAc is
attractive and indicates a high and promising potential for development