Defect related anomalous mobility of small polarons in dielectric oxides at the example of congruent lithium niobate.

Polarons play a major role in the description of optical, electrical and dielectrical properties of several ferroelectric oxides. The motion of those particles occurs by elementary hops among the material lattice sites. In order to compute macroscopic transport parameters such as charge mobility, normal (i.

Optical and Electrical Properties of A[VS] (A = Na, K) Synthesized via a Straightforward and Scalable Solid-State Method.

Two literature-known sulfido vanadates, Na[VS] and K[VS], were obtained through a straightforward and scalable synthetic method. Highly crystalline powders of both compounds were obtained from the homogeneous molten phases of starting materials via a─comparably rapid─solid-state technique. Low-temperature structure determination, ambient temperature powder diffraction, and solid-state NMR spectroscopy verify previous structural reports and indicate purity of the obtained samples.

Small electron polarons bound to interstitial tantalum defects in lithium tantalate.

The absorption features of optically generated, short-lived small bound electron polarons are inspected in congruent lithium tantalate, LiTaO(LT), in order to address the question whether it is possible to localize electrons at interstitial TaV:VLidefect pairs by strong, short-range electron-phonon coupling. Solid-state photoabsorption spectroscopy under light exposure and density functional theory are used for an experimental and theoretical access to the spectral features of small bound polaron states and to calculate the binding energies of the small bound TaLi4+(antisite) and TaV4+:VLi(interstitial site) electron polarons. As a result, two energetically well separated (ΔE≈0.

Gap-Free Tuning of Second and Third Harmonic Generation in Mechanochemically Synthesized Nanocrystalline LiNbTaO (0 ≤ ≤ 1) Studied with Nonlinear Diffuse Femtosecond-Pulse Reflectometry.

The tuning of second (SHG) and third (THG) harmonic emission is studied in the model system LiNb 1-xTa xO 3 (0≤x≤1, LNT) between the established edge compositions lithium niobate (LiNbO 3, x=0, LN) and lithium tantalate (LiTaO 3, x=1, LT). Thus, the existence of optical nonlinearities of the second and third order is demonstrated in the ferroelectric solid solution system, and the question about the suitability of LNT in the field of nonlinear and quantum optics, in particular as a promising nonlinear optical material for frequency conversion with tunable composition, is addressed. For this purpose, harmonic generation is studied in nanosized crystallites of mechanochemically synthesized LNT using nonlinear diffuse reflectometry with wavelength-tunable fundamental femtosecond laser pulses from 1200 nm to 2000 nm.

Remarkable Infrared Nonlinear Optical, Dielectric, and Strong Diamagnetic Characteristics of Semiconducting K[BiS].

The ternary sulfido bismuthate K[BiS] is synthesized in quantitative yields. The material exhibits nonlinear optical properties with strong second harmonic generation properties at arbitrary wavelengths in the infrared spectral range and a notable laser-induced damage threshold of 5.22 GW cm for pulsed laser radiation at a wavelength of 1040 nm, a pulse duration of 180 fs, and a repetition rate of 12.

Ca-activated sphingomyelin scrambling and turnover mediate ESCRT-independent lysosomal repair.

Lysosomes are vital organelles vulnerable to injuries from diverse materials. Failure to repair or sequester damaged lysosomes poses a threat to cell viability. Here we report that cells exploit a sphingomyelin-based lysosomal repair pathway that operates independently of ESCRT to reverse potentially lethal membrane damage.

NIR-to-NIR Imaging: Extended Excitation Up to 2.2 μm Using Harmonic Nanoparticles with a Tunable hIGh EneRgy (TIGER) Widefield Microscope.

Near-infrared (NIR) marker-based imaging is of growing importance for deep tissue imaging and is based on a considerable reduction of optical losses at large wavelengths. We aim to extend the range of NIR excitation wavelengths particularly to values beyond 1.6 μm in order to profit from the low loss biological windows NIR-III and NIR-IV.

Time evolution of Symmetry-forbidden Raman lines activated by photorefractivity.

Transmission Raman spectroscopy experiments were performed on iron doped congruent lithium niobate within two -in principle equivalent- configurations, namely Y(ZX)Y and Y(XZ)Y. While the former respects the Raman selection rules, the other configuration gives a time dependent spectrum that, after a transient time of several minutes, finally results in a mixture of expected and forbidden modes. This breaking of Raman selection rules is caused by the spontaneous conversion of a part of the ordinarily polarized pump beam into an extraordinarily polarized beam by photorefractive anisotropic self-scattering.

The elusive role of Nb bound polaron energy in hopping charge transport in Fe: LiNbO.

Charge transport due to small polarons hopping among defective (bound polarons) and regular (free polarons) sites is shown to depend in a non-trivial way on the value of the stabilization energy provided by the lattice distortion surrounding the charge carriers. This energy, normally not directly accessible for bound polarons using spectroscopic techniques, is determined here by a combination of experimental and numerical methods for the important case of small electron polarons bound to [Formula: see text] defects in the prototype ferroelectric oxide lithium niobate. Our findings provide an estimation of the [Formula: see text] polaron stabilization energy [Formula: see text] and demonstrate that in lithium niobate both free and bound polarons contribute to charge transport at room temperature, explaining the fast decay of the light-induced bound polaron population observed by transient absorption spectroscopy.