Monolayer transition metal dichalcogenides (1L-TMDs) are expected for applications to next-generation optoelectronic devices, owing to strong coupling with light. Optical properties of 1L-TMDs are dominated by excitons (electron-hole pairs), which are stable even at room temperature. This is because exciton binding energies are as large as a few hundred meV, derived from the atomic thickness. The low-dimensionality also gives arise to the nonhydrogenic energy level structure of 1L-TMDs excitons unlike those in bulk semiconductors [1]. So far, phenomenological Rytova-Keldysh potential [2], [3] is used for the analyses on the s-series exciton level structure observed in linear spectroscopies [4], [5]. In addition, Berry curvature effects are expected to contribute to the splitting of p-series excitons observed in third-order nonlinear optical responses [6]. However, no unified model picture has been established for the 1L-TMDs exciton level structure.
Recent advancement in high-power mid-infrared lasers has facilitated the investigation of extreme nonlinear optical phenomena in solids, which exhibit unconventional behaviors owing to strong light–matter interactions. High-harmonic generation (HHG) is a typical phenomenon that generates harmonics through nonperturbative processes. Herein, the strong laser field tunnels the charged particles from the valence to the conduction band and induces their carrier motion along the band, and then their motion generates high harmonics. In this study, we demonstrate that both the location of the Fermi level and the intensity of the laser field significantly affect the tunneling process in semiconducting carbon nanotubes through experimental measurements and theoretical calculations. Additionally, on- or off-tunneling can determine the nonperturbative or perturbative harmonic generation processes, respectively, and this crossover can be observed owing to the shift in the gate voltage. Tuning the Fermi level and laser intensity is crucial for manipulating the tunneling process, carrier oscillations, and harmonic generation mechanisms. The results provide further insights into the nonlinear optical processes of semiconductors and pave the way for precisely controlling HHG in solids by using a static electric field.
Abstract The reaction is only successful with an aryl substituent at the 2‐position of the thiophene and the unique tricyclic skeletons are obtained as single diastereomers.
Incubation period involved in the photo-induced phase transition has been studied by monitoring electron paramagnetic resonance signal. The incubation periods sub-linearly depend on the irradiating light power in higher power region. [Fe II (2-pic)3]Cl2EtOH (Fe-pic) exhibits the photo-induced phase transition (PIPT) from a diamagnetic phase to a paramagnetic phase at low temperature. In the PIPT, cooperative intersystem crossing mediated by spin lattice interaction play a key role 1) . Electron paramagnetic resonance (EPR) spectroscopy is one of the most powerful tools to study local structure surrounding a localized spin. In this study, dynamics of the local structural change in PIPT has been monitored by ESR signals of doped Co 2+ ions.
In a polar material, a laser pulse can trigger nonlinear optical phenomena, such as second-harmonic generation (SHG). The authors investigate the variation of SHG in BiCoO${}_{3}$ upon irradiation with femtosecond terahertz pulses. Applying a THz pulse, they observe enhancement of SHG by more than 50% at room temperature, the response being so fast that it simply follows the THz pulse. This huge, ultrafast enhancement, explained in terms of a photon dressed state, could be used to control nonlinear optical properties at the femtosecond timescale.
Fatal cases with the use of atypical antipsychotic drug paliperidone have been reported; however, there was no clinical report describing paliperidone-induced torsade de pointes. In this study we assessed its electropharmacological effects together with its proarrhythmic potential in intravenous doses of 0.03, 0.3 and 3 mg/kg using the halothane-anesthetized dogs (n = 5), which could provide approximately 2, 20 and 200 times higher peak plasma drug concentrations than its therapeutic level, respectively. Paliperidone exerted potent vasodilator effect resulting in hypotension, which may be largely explained by its α1-adrenoceptor blocking action. In vivo electrophysiological results suggest that paliperidone may inhibit human ether-à-go-go-related gene K+ channel in a dose-related manner and modestly suppress Na+ channel in the in situ heart. The high dose of paliperidone may have some potential to induce early afterdepolarization that can trigger lethal ventricular arrhythmias, whereas the low and middle doses lack such proarrhythmic possibility, indicating that at least 20 times higher plasma concentration may be considered to be safe.
A terahertz microscope has been used to excite and observe the resonant modes of a single split ring resonator in the reactive and radiative near-field zones. The two lowest resonant modes of an isolated split ring resonator with their corresponding radiation patterns are reported; they showed good agreement to simulations. The passage from the reactive to radiative near-field zone is also discussed. Further, our result introduced a novel technique to perform terahertz time-domain spectroscopy of samples a few tens of micrometers in size by measuring the in-plane radiative near-field zone.
