High electrical-to-green efficiency high stability intracavity-frequency-doubled Nd:YAG-LBO QCW 532 nm laser with a straight cavity

An electrical-to-green efficiency of more than 10% was demonstrated by intracavity-frequency-doubling a Q-switched diode-side-pumped Nd:YAG laser with a type II lithium triborate (LBO) crystal in a straight plano-concave cavity. An average power of 69.2 W at 532 nm was generated when electrical input power was 666 W. The corresponding electrical-to-green conversion efficiency is 10.4%. To the best of our knowledge, this is the highest electrical-to-green efficiency of second harmonic generation laser systems with side-pumped laser modules, ever reported. At about 66 W of green output power, the power fluctuation over 4 hours was better than +/-0.86%.

Photodissociation dynamics of the methyl radical at 212.5 nm: Effect of parent internal excitation

Photodissociation dynamics of the CH3 radical at 212.5 nm has been investigated using the H atom Rydberg tagging time-of-flight method with a pure CH3 radical source generated by the photolysis of CH3I at 266 nm. Time-of-flight spectra of the H atom products from the photolysis of both cold and hot methyl radicals have been measured at different photolysis polarizations. Experimental results indicate that the photodissociation of the methyl radical in its ground vibrational state at 212.5 nm excitation occurs on a very fast time scale in comparison with its rotational period, indicating the CH3 dissociation at 212.5 nm occurs on the excited 3s Rydberg state surface. Experimental evidence also shows that the photodissociation of the methyl radical in the nu(2)=1 state of the umbrella mode at 212.5 nm excitation is characteristically different from that in the ground vibrational state. (C) 2004 American Institute of Physics.

Mass resolved MPI spectra of methyl iodide in the 430-490 nm region

The mass resolved multiphoton ionization (MPI) spectra of methyl iodide were obtained in the 430-490 nm region using a time-of-flight (TOF) mass spectrometer. They have the same vibrational structure, which testifies that the fragment species, in the wavelength region under study, are from the photodissociation of multiphoton ionized molecular parent ions. Some features in the spectra are identified as three-photon excitations to 6p and 7s Rydberg states of methyl iodide. Two new vibrational structures of some Rydberg states are observed. The mechanism of ionization and dissociation is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

A velocity map ion-imaging study on C2H5SH and C3H7SH photodissociation at 243 nm

Photodissociation dynamics Of C2H5SH, i-C-3-H7SH and n-C3H7SH at 243.1 nm were investigated using velocity map ion-imaging method. H-atom photolysis products were detected by a (2 + 1) resonance enhanced ionization scheme. Both the angular distribution and translational energy distribution of the H-atom elimination processes were determined from the ion images of the H-atom products. The experimental results indicate that the H-atom eliminations from these molecules are mainly direct and fast dissociation processes from a repulsive potential energy state. And a more statistical dissociation process that likely occurs oil the ground state via internal conversion has also been observed. Dissociation energies of the S-H bonds are also derived from the H-atom product translational energy distributions. (C) 2002 Elsevier Science B.V. All rights reserved.

Green synthesis of 1-2 nm gold nanoparticles stabilized by amine-terminated ionic liquid and their electrocatalytic activity in oxygen reduction

Stable gold nanoparticles with average size 1.7 nm synthesized by an amine-terminated ionic liquid showed enhanced electrocatalytic activity and high stability.

Single-crystal-like organic heterojunction with 40 nm thick charge accumulation layers

Single-crystal-like organic heterojunction films of copper phthalocyanine (CuPc) and copper-hexadecafluoro-phthalocyanine (F16CuPc) were fabricated by weak-epitaxy-growth method. The intrinsic properties of organic heterojunction were revealed through threshold voltage shift of field-effect transistors and measurement of single-crystal-like diodes. At both sides of the heterojunction interface 40 nm thick charge accumulation layers formed, which showed that the long carriers' diffusion length is due to the high crystallinity and low density of deep bulk traps of single-crystal-like films.

Controllable Red, Green, Blue (RGB) and Bright White Upconversion Luminescence of Lu2O3:Yb3+/Er3+/Tm3+ Nanocrystals through Single Laser Excitation at 980 nm

Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode laser excitation of 980 nm, the bright blue emissions of Lu2O3:Yb3+, Tm3+ nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-> H-3(6) transition of Tm3+. The bright green UC emissions of Lu2O3:Er3+ nanocrystals appeared near 540 and 565 nm were observed and assigned to the H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) transitions, respectively, of Er3+. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb3+ in Lu2O3:Er3+ nanocrystals.

Simple and Efficient Near-Infrared Organic Chromophores for Light-Emitting Diodes with Single Electroluminescent Emission above 1000 nm

A series of NIR organic chromophores with donor-pi-acceptor-pi-donor structure are synthesized. Good thermal stability and strong photoluminescence in solid state render them suitable for application in light-emitting diodes. Exclusive near-infrared emission at 1080 nm with external quantum efficiency of 0.28% is obtained from the nondoped OLEDs. The longest electroluminescence wave-length is 1220 nm.