Institute of Ion Plasma Laser Technologies

Abstract A series of sulfide nanocrystals was prepared using a new reagent. The properties of the nanocrystals and of thin films containing them were investigated using spectroscopic, morphological and nonlinear optical methods. The two-photon absorption, three-photon absorption, and saturable absorption of the thin (30–80 nm) films containing different number of layers of the nanocrystals of three sulfides (Ag 9 GaS 6 , AgInS 2 , and CuGaS 2 ) were studied using the 1030 nm and 515 nm, 200 fs probe pulses. The prevailing role of either saturable absorption or three-photon absorption was demonstrated in the case of Ag 9 GaS 6 and CuGaS 2 films by varying the intensity of the 1030 nm probe pulses. In the case of 515 nm probe pulses, the two-photon absorption in AgInS 2 film was observed at small intensities followed by saturable absorption at higher intensities of the probe pulses. The three-photon absorption coefficients of Ag 9 GaS 6 and CuGaS 2 films were measured to be 2.2 × 10 –21 cm 3 W− 2 and 6 × 10 –19 cm 3 W −2 , while two-photon absorption coefficient of AgInS 2 film was determined to be 3.6 × 10 11 cm 1 W −1 .

The saturable absorption and two-photon absorption of the thin films containing the quantum dots (QD) of several metal sulfides and selenides (Ag 2 S, PbS, Ag 2 Se, and PbSe) are studied using the 1030 nm and 515 nm, 200 fs probe pulses. The prevailing role of saturable absorption and two-photon absorption in films was determined by varying the intensity of the probe pulses. The nonlinear optical parameters of the above processes are calculated. The strong two-photon absorption in PbS and PbSe QD films in the case of the 515 nm probe pulses is revealed. The growth of the nonlinear absorption in the QD films compared to the colloids containing similar species is attributed to the growing influence of the local field introduced by QDs in the films. The potential applications of the studied QD films are discussed.

Anode-free sodium batteries (AFSBs) hold great promise for high-density energy storage. However, high-voltage AFSBs, especially those can stably cycle at a wide temperature range are challenging due to the poor electrolyte compatibility toward both the cathode and anode. Herein, high-voltage AFSBs with cycling ability in a wide temperature range (-20-60°C) are realized for the first time via a sole-solvent high-entropy electrolyte based on the diethylene glycol dibutyl ether solvent (D2) and NaPF6 salt. The sole-solvent high-entropy electrolyte with unique solvent-ions effect of strong anion interaction and weak cation solvation enables entropy-driven electrolyte salt disassociation and high-concentration contact ion pairs, thus simultaneously forming stable anion-derived electrode-electrolyte interphases on cathode and anode. Moreover, the wide liquid range of D2 further extends the temperature extremes of the battery. Consequently, ampere-hour (Ah)-level anode-free sodium pouch cells with cyclability in a wide temperature range of -20-60°C are realized. Impressively, the pouch cell achieves a leadingly high cell-level energy density of 209Wh kg-1 and a high capacity retention of 83.1% after 100 cycles at 25°C. This work provides inspirations for designing advanced electrolytes for practical AFSBs.

The objective of the present study is to investigate desorption of low-volatility analytes in Leidenfrost phenomenon-assisted thermal desorption (LPTD). LPTD was investigated for 5μL solutions of 0.03 ppm cocaine or morphine in methanol (sample weight: 0.12 ng) by using heated metal surfaces (240°C) polished by abrasives with grit numbers from #5000 (~3μm) to #100 (~200 μm). The analyte signals were detected only after the complete evaporation of methanol solvent and the formed analyte residues levitated on the heater surface. The strongest ion signals were obtained with grit number #100. Because the analyte residue does not come into contact with the heated surface but levitates on the hot substrate after the evaporation of the solvent, thermal decomposition of the analyte is largely suppressed. This is a great merit of LPTD for trace analysis of low-volatility and thermally labile compounds.

A method for producing a thin semiconductor film of antimony selenide (Sb2Se3) via vacuum thermal evaporation with the assistance of an electric field was presented. The morphological, elemental and structural properties of the thin films were characterized using X-ray diffraction and scanning electron microscopy (with energy dispersive X-ray spectroscopy). It was found that an applied constant electric field plays an important role in obtaining Sb2Se3 thin films with the desired morphological and structural properties. The latter is a useful tool for controlling charge transport properties in thin films.