GaN quantum wells in an AlN matrix are characterized using scanning transmission electron microscopy. The width of the quantum wells and sharpness of the interfaces are measured with composition sensitive annular dark field imaging and electron energy-loss spectroscopy. The effects of beam broadening inside the specimen are discussed and mechanisms to minimize it are suggested. The quantitative...

We show that with spatially incoherent illumination, the point spread function width of an imaging interferometer like that used in full-field optical coherence tomography (FFOCT) is almost insensitive to aberrations that mostly induce a reduction of the signal level without broadening. This is demonstrated by comparison with traditional scanning OCT and wide-field OCT with spatially coherent i...

We report the generation of high-repetition-rate femtosecond pulses in the blue by intracavity doubling of a mode-locked Ti:sapphire laser using ,f-BaB204. To reduce the pulse-broadening effect of group-velocity mismatch, an extremely thin p-BaB204 crystal is used. By pumping the Ti:sapphire laser with 4.4 W of power from an Ar' laser, as much as 230 mW of 430-nm light is produced at a 72-MHz r...

2014 We show that the pressure broadening of the width 2 ~(4 V2 + (01270393)2) of an anticrossing signal (where V is the coupling between the anticrossing levels and 0393 the reciprocal of their lifetime) is caused by more than just the increase of 0393 by collisions. We find that the linewidth is given by 2 ~(4 V2 ab03B3/03B3 + (0127 ab03B3)2), where ab03B3/03B3 is the ratio of the effective r...

The new technique of cavity enhanced velocity modulation spectroscopy has been further developed, incorporating a tighter cavity to laser lock and an optical frequency comb for absolute frequency calibration. Several N2 transitions have been observed with much higher precision than previously possible, and transitions that were blended in earlier Doppler-limited experiments are now resolved. Th...

Injection mode locking of large-aperture TEA CO 2 lasers makes it possible to generate nanosecond pulses with high intensities [ 1 3 ] . It was shown by Dyer and Perera [6] that by injection mode locking the width of the amplified pulse depends on many variables, such as the width of the injected pulse from the master oscillator and the gas pressure of the slave oscillator. They studied the bro...

The mobile SOUSY VHFRadar was operated in the summer of 1987 during the MAC/SINE campaign in northern Norway to study the polar mesosphere summer echoes (PMSE). Measurements of the spectral width indicate that two types of structures occur. In general mesospheric layers are bifurcated exhibiting a narrow spectral width and a well-de®ned aspect sensitivity. However, for about 10% of the observat...

We calculate the absorption spectra of a conductive disk in presence metal gate. In our analysis, we use conductivity described by Drude model. examine frequency and line width resonances associated with excited plasma waves. They are estimated both numerically analytically for fundamental axisymmetric modes. The is determined collisional radiative losses. high mobility samples, latter may domi...

Carbon monoxide dehydrogenase (CODH) catalyzes the reversible oxidation of CO to CO2 at a nickel-iron-sulfur cluster (the C-cluster). CO oxidation follows a ping-pong mechanism involving two-electron reduction of the C-cluster followed by electron transfer through an internal electron transfer chain to external electron acceptors. We describe 13C NMR studies demonstrating a CODH-catalyzed stead...