Electronic interactions in a branched chromophore investigated by nonlinear optical and time-resolved spectroscopy J. Chem. Phys. 120, 337 (2004); 10.1063/1.1630309Study of hyper-Rayleigh scattering and two-photon absorption induced fluorescence from crystal violet Three two-photon active boradiazaindacene derivatives named 2,6-di-͑phenylacetylenyl͒-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene ͑3a͒, 2,6-di-͑9-ethyl-9H-carbazole-3-ethynyl͒-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene ͑3b͒, and 2,6-di-͑4-N,N-diphenyl-phenylacetylenyl͒-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene ͑3c͒ in tetrahydrofuran solutions were systematically investigated by using the femtosecond laser spectroscopic techniques. The two-photon absorption cross sections of 3a, 3b and 3c were determined to be 29 GM, 46 GM, and 60 GM, respectively, increasing with the increase in strength of the electron-donor groups. The relaxation dynamics of the excited states measured by femtosecond pump-probe experiments reveal a broad region of stimulated radiation of the excited states and the different relaxation process happened in these compounds. The preliminary two-photon fluorescence imaging experiment show their good cell permeability, nontoxicity, and excellent two-photon fluorescence properties.

A kind of glass-in-LuAG (GIP) ceramic with excellent luminous efficiency and high thermal stability was fabricated by solid-state sintering for laser diode (LD)-pumped green-emitting phosphor. The GIP ceramic employing particularly designed borosilicate glass as adhesive exhibits high thermal conductivity (2.8  W/m·K at 80°C) and remarkable improvement in thermal stability (T=711°C) and reliability (luminous flux has only a 0.5% drop after 100 h at 300°C). When the GIP ceramic is pumped by 455 nm blue LDs (14.5  W/mm), a luminous efficacy of 205 lm/W was achieved. More importantly, the GIP ceramic did not have luminescence saturation even under a higher power density (17.1  W/mm) excitation. The novel GIP ceramic, possessing good optical and thermal properties, is promising for LD-pumped green-emitting phosphor.

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The quantum dynamics of a V-type three-level system, whose two resonances are first excited by a weak probe pulse and subsequently modified by another strong one, is studied. The quantum dynamics of the multi-level system is closely related to the absorption spectrum of the transmitted probe pulse and its modification manifests itself as a modulation of the absorption line shape. Applying the dipole-control model, the modulation induced by the second strong pulse to the system’s dynamics is quantified by eight intensity-dependent parameters, describing the self and inter-state contributions. The present study opens the route to control the quantum dynamics of multi-level systems and to quantify the quantum-control process.

Boundary layer suction is used in turbomachinery to control flow separation to enhance the loading capacity of a compressor. This paper focuses on both numerical calculation and experimental investigation with boundary layer suction holes made in the suction surface of a compressor cascade with a large camber angle. Experimental and numerical investigations are carried out with suction holes in different positions. In the experimental investigation, exit aerodynamic parameters are measured using a five-hole aerodynamic probe, and ink-trace flow visualization is adopted on cascade surface. Experimental and numerical results indicate that both side and middle suctions on the suction surface can efficiently remove low-energy fluid to increase the cascade load capacity while they effectively restrain the corner flow separation. The cascade aerodynamic performance is obviously improved by middle and side suctions, and it is also significantly altered by the position of suction changes. The middle suction holes have their best positions at about 60–66% chord length from the leading edge, and the side suction holes have their best positions a little downstream the corner separation line.