Vibrational spectra of serotonin by terahertz time domain spectroscopy and DFT simulations.

Serotonin is an important biogenic monoamine neurotransmitter that has major influences on mental health disorders; its structural and conformational changes have important roles in the biological functions of the human body. The decreased serotonin levels in the human body are majorly attributed to the causes of anxiety, depressive disorders, mood disorders, etc. Therefore, the quantification of serotonin in our bodies is of utmost importance in unearthing the origin of such physiological disorders.

Plasmon-enhanced optical nonlinearity in pyramidal silver nanocrystals.

This study investigates the coherent optical nonlinearity of two sets of anisotropic silver nanocrystals (NCs) showing plasmon peaks at 530 and 610 nm (hence named Ag-530 and Ag-610 NCs, respectively). The nonlinear optical (NLO) properties of Ag-530 and Ag-610 NCs are compared with spherical silver NCs exhibiting plasmon peak at 420 nm (hence called Ag-420 NCs). Resonant excitation induces significant one-photon absorption (1PA) saturation for all NCs, with Ag-610 NCs displaying exceptional transparency.

Two-Photon-Responsive "TICT + AIE" Active Naphthyridine-BF Photoremovable Protecting Group: Application for Specific Staining and Killing of Cancer Cells.

The combined effects of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) phenomena have demonstrated a significant influence on excited-state chemistry. These combined TICT and AIE features have been extensively utilized to enhance photodynamic and photothermal therapy. Herein, we demonstrated the synergistic capabilities of TICT and AIE phenomena in the design of the photoremovable protecting group (PRPG), namely, NMe-Napy-BF.

Observing ice structure of micron-sized vapor-deposited ice with an x-ray free-electron laser.

The direct observation of the structure of micrometer-sized vapor-deposited ice is performed at Pohang Accelerator Laboratory x-ray free electron laser (PAL-XFEL). The formation of micrometer-sized ice crystals and their structure is important in various fields, including atmospheric science, cryobiology, and astrophysics, but understanding the structure of micrometer-sized ice crystals remains challenging due to the lack of direct observation. Using intense x-ray diffraction from PAL-XFEL, we could observe the structure of micrometer-sized vapor-deposited ice below 150 K with a thickness of 2-50 m grown in an ultrahigh vacuum chamber.

Temporal Release of Cell Cycle Regulator α-Lipoic Acid: An NIR-Light (Two-Photon) Activatable Quinoxaline-Based Nano-Prodrug Delivery System.

The regulation of the cell cycle has recently opened up a new research perspective for cancer treatment. So far, no effort has been made for temporal control of cell cycles using a photocleavable linker. Presented herein is the first report of regulation of disrupted cell cycles through the temporal release of a well-known cell cycle regulator α-lipoic acid (ALA), enabled by a newly designed NIR-active quinoxaline-based photoremovable protecting group (PRPG).

A two-photon responsive hydroxyphenylquinazolinone (HPQ)-based fluorescent organic nanoprodrug for HS release against oxidative stress.

Light-activated HS donors have attracted considerable interest in understanding the physiological role and clinical potential of HS, as their release is highly localized and controlled. Herein, we have evolved a new HPQ chromophore-based fluorescent organic nanosystem localized in a target area that tolerates oxidative stress and precisely releases HS under one- and two-photon irradiation with real-time monitoring capability. The two-photon absorption cross-section of this new phototrigger was calculated to be 283 GM at 720 nm.

Adipic acid directed self-healable supramolecular metallogels of Co(II) and Ni(II): intriguing scaffolds for comparative optical-phenomenon in terms of third-order optical non-linearity.

Two brilliant outcomes of supramolecular self-assembly directed, low molecular weight organic gelator based self-healable Co(II) and Ni(II) metallogels were achieved. Adipic acid as the low molecular weight organic gelator and dimethylformamide (DMF) solvent are employed for the metallogelation process. Rheological analyses of both gel-scaffolds reveal mechanical toughness as well as visco-elasticity.

One- and Two-Photon Uncaging of Carbon Monoxide (CO) with Real-Time Monitoring: On-Demand Carbazole-Based Dual CO-Releasing Platform to Test over Single and Combinatorial Approaches for the Efficient Regression of Orthotopic Murine Melanoma .

Herein, we report three new metal-free, photochemically active single, dual, and combinatorial CORMs (photoCORMs) based on a carbazole-fused 1,3-dioxol-2-one moiety which released one equivalent of CO, two equivalent of CO, and a combination of one equivalent of each CO and anticancer drug upon one- and two-photon excitation, respectively. The photoCORMs exhibited good cellular uptake and real-time monitoring ability of CO uncaging by a color change approach in cancerous B16F10 cells. Interestingly, the cytotoxicity assay on B16F10 cells indicated that the dual photoCORM has increased anticancer activity over the single and combinatorial photoCORMs upon irradiation.

Unusual higher-order nonlinear optical properties in Au-coated triangular Ag-Au nanostructures.

Here, we report hitherto unobserved local field (LF)-assisted pump wavelength-dependent nonlinear optical (NLO) effects of three-photon (3PA)-induced four-photon absorption (4PA) at 532 nm and two-photon-induced 3PA at 730 nm in triangular-shaped core-shell Ag-Au nanoparticles (TrAg@Au) by femtosecond Z-scan. The shell thickness-dependent enhancement in the LF is observed by a COMSOL simulation. The intensity-dependent interplay between saturable and reverse-saturable absorptions along with switching of nonlinear (NL) phase is reported at 730 nm, showing the superiority of TrAg@Au in optical switching (OS).

Is the origin of green fluorescence in unsymmetrical four-ring bent-core liquid crystals single or double proton transfer?

The origin of green fluorescence in unsymmetrical four-ring bent-core liquid crystals (BCLCs) is not understood clearly. There is no analysis of the photo-physical properties, in particular, the excited state dynamical behaviour, of these molecules. Because of the availability of two proton transfer sites in these systems, there is no clear explanation of the involvement of single or double proton transfer reactions in the origin of the large Stokes shifted green fluorescence band.

Electrical transport properties and ultrafast optical nonlinearity of rGO-metal chalcogenide ensembles.

In recent times, nanomaterials that harvest solar radiation and transform it into other forms of energy are of considerable interest. Herein, the electrical transport properties of reduced graphene oxide (rGO), rGO-zinc selenide (rGO-ZnSe) and rGO-zinc telluride (rGO-ZnTe) thin films have been investigated at 87-473 K under both dark and illumination conditions. A comparative study of photosensitivity () and charge carrier mobility (), calculated using a trap-free space charge limited current model, shows the highest values for 54 wt% ZnSe and 50 wt% ZnTe contents (namely samples C1 and C2, respectively).

Core/Shell Nanocrystal Tailored Carrier Dynamics in Hysteresisless Perovskite Solar Cells with ∼20% Efficiency and Long Operational Stability.

The ambient stability, hysteresis, and trap states in organo-halide perovskite solar cells (PSCs) are correlated to the influence of interlayer interfaces and grain boundaries. Astute incorporation of CuZnSnS (CZTS) and Au/CZTS core/shell nanocrystals (NCs) can realize the goal of simultaneously achieving better performance and ambient stability of the PSCs. With optimized Au/CZTS NC size and concentration in the photoactive layer, power conversion efficiency can be increased up to 19.

Third-order optical nonlinearity of the CuCoTiO nanostructure under 120 fs laser irradiation.

Recently, titanium-based nanostructures with high nonlinear optical properties have found use in ultrafast photonic system applications. Here, we report a study of the third-order nonlinear optical property of the ${{\rm CuCo}_{0.5}}{{\rm Ti}_{0.

Stepwise dual stimuli triggered dual drug release by a single naphthalene based two-photon chromophore to reverse MDR for alkylating agents with dual surveillance in uncaging steps.

In this work, we depleted glutathione (GSH) by releasing SO2 with internal stimulus GSH itself, and also selectively marked the cancer cells followed by release of anticancer drug using another orthogonal stimulus i.e., two-photon (TP) NIR light by a single naphthalene based chromophore (TP absorbance 77 GM and uncaging cross-section 21 GM).

Photoinduced Bending of Single Crystals of a Linear Bis-Olefin via Water-Templated Solid-State [2+2] Photopolymerization Reaction.

The single crystals of two structural isomers of bis-olefinic molecules were shown to have contrasting properties in terms of their photoreactivity: one exhibits an excellent ability to form polymers, accompanied with bending of crystals upon irradiation, while the other is photostable. The photoreactive crystal is a first example in which [2+2] polymerization leads to bending of the crystals, with implications for the design of photoactuators. The hydrate formation ability of one of these molecular isomers promotes the solid-state reactivity in its crystal, as the H O molecules act as a template to bring the olefin molecules into the required arrangement for [2+2] polymerization.

Highly stable photoelectrochemical cells for hydrogen production using a SnO-TiO/quantum dot heterostructured photoanode.

Photoelectrochemical (PEC) water splitting implementing colloidal quantum dots (QDs) as sensitizers is a promising approach for hydrogen (H2) generation, due to the QD's size-tunable optical properties. However, the challenge of long-term stability of the QDs is still unresolved. Here, we introduce a highly stable QD-based PEC device for H2 generation using a photoanode based on a SnO2-TiO2 heterostructure, sensitized by CdSe/CdS core/thick-shell "giant" QDs.

Anomalous Dynamics in -Butyl Alcohol-Water and Trimethylamine -Oxide-Water Binary Mixtures: A Femtosecond Transient Absorption Study.

In this article, we have investigated the unusual dynamics of -butyl alcohol (TBA)-water and trimethylamine -oxide (TMAO)-water binary mixtures using solvation dynamics as a tool. For this purpose, femtosecond transient absorption spectroscopy has been employed. Although these two molecules are isosteres to each other, a significant difference in water dynamics has been observed.

Dynamic gain aperture modelocking in picosecond regime based on cascaded second-order nonlinearity.

The operation of a cascaded second-order mode-locked Nd:YVO laser has been investigated considering it as a soft-aperture Kerr lens type and using complex beam parameters. A self consistent complex beam propagation method is used to incorporate the effect of cascaded Kerr nonlinearity on radially varying gain aperturing. The analysis deduces a stable pulsewidth of ~9.

Effect of including intraband phenomena in the semiconductor optical amplifier model for propagation of short pulses.

A comparison has been done between the two cases when intraband effects are included and when they are excluded in the semiconductor optical amplifier model for propagating short pulses. The numerical investigation shows that the dependence of output pulse chirping and broadening on the amplifier gain, input pulse energy, and input pulsewidth becomes stronger on inclusion of intraband effects. To prove the experimental fact of pulsewidth dependency of the amplifier saturated gain for short pulses, it is compulsory to include intraband effects in the model.

Dual colour cw mode-locking through soft aperture based on second order cascaded nonlinearity.

Large nonlinear phase shift achieved by exploiting intracavity second order cascaded nonlinear process in a non-phasematched second harmonic generating crystal is transformed into amplitude modulation through soft aperturing the nonlinear cavity mode variation within the laser gain medium to mode-lock a Nd:YVO4 laser. The laser delivers stable dual wavelength cw mode-locked pulse train with pulse duration 10.3 ps and average power of 1.

Nonlinearly coupled, gain-switched Nd:YAG second harmonic laser with variable pulse width.

An all-solid-state, gain-switched, green laser is developed using a side diode-array pumped Nd:YAG laser and a KTiOPO(4) (KTP) crystal as an intracavity frequency doubler. The effect of nonlinear coupling on the pulse width of the fundamental is studied and is found to be in good agreement with the experimental measurement. In this preliminary experiment, a peak power of 40 W at 532 nm corresponding to a pulse width of 409 ns is obtained for an average pump power of 2 W.

Simultaneous multi-wavelength oscillation of Nd laser around 1.3 mum: A potential source for coherent terahertz generation.

Simultaneous oscillations of 1318.8nm, 1320.0nm, 1332.

Picosecond pulse generation and its simulation in a nonlinear optical mirror mode-locked laser.

A nonlinear mirror composed of a lithium triborate crystal and a dichroic output coupler is used to passively mode lock an Nd:YVO4 laser that is pumped by a diode laser array. A mode-locked output power of 3.2 W, a repetition rate of 178 MHz, a pulse width of 8.