Time-resolved photocurrent at the MoSe2—I− photoelectrode studied with a nanosecond pulsed laser

A time-resolved transient photocurrent in the nanosecond region when illuminating the MoSe₂ — I^? semiconductorliquid junction with a pulsed laser, consists of a rapid one which immediately follows the incident light pulse and of another one with a slower decay. From the dependence of the photocurrent on light intensity, bias voltage and the effective concentration of the electrolyte, the two observed components in the spectrum were explained to originate from charge-carrier generation in the solid and electron transfer across the electrode interface, respectively.     

Diode-pumped distributed-feedback dye laser with an organic–inorganic microcavity

We present a diode-pumped microcavity dye laser composed of a top organic reflector and a bottom inorganic reflector. The top organic reflector consists of alternate thin films of cellulose acetate and poly(N-vinylcarbazole) doped with coumarin 540A to construct a distributed-feedback (DFB) resonator. Pumped directly by an InGaN-based blue laser diode (LD) with a pulse duration of 4 ns, the microcavity dye laser exhibited a single-mode oscillation at 563 nm with a threshold pump LD power of 290 mW/pulse. The emission of the microcavity dye laser was measured through an optical fiber, resulting in a peak power of 2.5 mW for a pump LD power of 320 mW. PACS  42.55.Mv; 42.55.Sa; 42.55.Xi     

Low-threshold strained multi-quantum well lasers fabricated by selective metalorganic vapor phase epitaxy without a semiconductor etching process

Strained InGaAsP multi-quantum well (MQW) buried hetero- (BH) laser diodes (LDs) on a p-InP substrate were fabricated by selective metalorganic vapor phase epitaxy (MOVPE). In the laser fabrication process, both the strained MQW active layer and current blocking structure were directly formed by selective MOVPE without a semiconductor etching process. This novel laser fabrication process produces extremely uniform device characteristics that are essential to the deployment of optical subscriber systems. Furthermore, important device design parameters (e.g. the active stripe shape or the leakage current path configuration) are precisely controlled by only the epitaxial growth steps. This highly controllable laser fabrication method results in a very low-threshold current with excellent uniformity (I_th = 1.78 ± 0.19 mA) for 20 consecutive LDs (L = 200 μm with 70%–90% coatings).     

A revised synthetic scheme of 6,6′‐dibromoindirubin

The synthetic scheme of 6,6′‐dibromoindirubin ( 2 ) was investigated in detail. The reaction of 6‐fluoro‐3‐acetoxyindole ( 7 ) with isatin ( 8 ) in methanol with Na₂CO₃ produced 6′‐fluoroindirubin in moderate yields. Its structure determination was mainly undertaken using ¹H NMR spectroscopy. On the basis of this result, the synthetic scheme of 2 reported by Cooksey was revised.     

Noncontact atomic force microscopy of perfect single crystals of pentacene prepared by crystallization from solution

Nearly perfect single crystals of pentacene were grown from trichlorobenzene solution. The surface structure of pentacene single crystals has been investigated by frequency modulation atomic force microscopy. Molecularly flat and extraordinarily wide terraces, extended over the width of more than a few micrometers with monomolecular steps, were consistently observed, suggesting that those pentacene crystals were nearly perfect single crystals. Molecular packing arrangements were revealed by FM-AFM for the first time.