Crystallization growth rates and front propagation in amorphous solid water films.

The growth rate of crystalline ice (CI) in amorphous solid water (ASW) films was investigated using reflection absorption infrared spectroscopy. Two different experiments were set up to measure rates of the crystallization front propagation from the underlying crystalline template upward and from the vacuum interface downward. In one set of experiments, layers of ASW (5% DO in HO) were grown on a CI template and capped with a decane layer.

Halide Perovskites for Nonlinear Optics.

Halide perovskites provide an ideal platform for engineering highly promising semiconductor materials for a wide range of applications in optoelectronic devices, such as photovoltaics, light-emitting diodes, photodetectors, and lasers. More recently, increasing research efforts have been directed toward the nonlinear optical properties of halide perovskites because of their unique chemical and electronic properties, which are of crucial importance for advancing their applications in next-generation photonic devices. Here, the current state of the art in the field of nonlinear optics (NLO) in halide perovskite materials is reviewed.

Chiral Lead Halide Perovskite Nanowires for Second-Order Nonlinear Optics.

Hybrid organic/inorganic lead halide perovskites (LHPs) have recently emerged as extremely promising photonic materials. However, the exploration of their optical nonlinearities has been mainly focused on the third- and higher-order nonlinear optical (NLO) effects. Strong second-order NLO responses are hardly expected from ordinary LHPs due to their intrinsic centrosymmetric structures, but are highly desirable for advancing their applications in the next generation integrated photonic circuits.

Controlling the Growth of Molecular Crystal Aggregates with Distinct Linear and Nonlinear Optical Properties.

Two novel donor-acceptor molecules, 2,7-diphenylbenzo[1,2-b:4,3-b']difuran-4,5-dicarbonitrile and 2,7-bis(4-methoxyphenyl)benzo[1,2-b:4,3-b']difuran-4,5-dicarbonitrile containing cyano group as the electron acceptor, were synthesized. Their single-crystal structures, molecular packing, and self-assembly behaviors were also investigated. By simple solvent evaporation techniques, these compounds self-assemble into various low-dimensional microstructures that demonstrate distinctive nonlinear optical properties depending on the orientations of their transition dipoles.

Communication: Distinguishing between bulk and interface-enhanced crystallization in nanoscale films of amorphous solid water.

The crystallization of amorphous solid water (ASW) nanoscale films was investigated using reflection absorption infrared spectroscopy. Two ASW film configurations were studied. In one case the ASW film was deposited on top of and capped with a decane layer ("sandwich" configuration).

Lyman-α photodesorption from CO2(ice) at 75 K: role of CO2 vibrational relaxation on desorption rate.

The photodesorption of CO2 from CO2(ice) at 75 K when irradiated by Lyman-α light is strongly mediated by vibrational relaxation of highly vibrationally excited molecules produced from the electronically excited CO2 state. A vibrationally hot molecule can either relax (major process) in the ice or desorb (minor process). We find that isotopically pure CO2 ices photodesorb least efficiently due to efficient vibrational tuning between molecules in the ice.

Isotope effect in the photochemical decomposition of CO2 (ice) by Lyman-α radiation.

The photochemical decomposition of CO2(ice) at 75 K by Lyman-α radiation (10.2 eV) has been studied using transmission infrared spectroscopy. An isotope effect in the decomposition of the CO2 molecule in the ice has been discovered, favoring (12)CO2 photodecomposition over (13)CO2 by about 10%.