Photopatterning of graphene oxide films can be achieved by exposing a thin film of graphene oxide to a photographic flash. Absorption of light causes rapid heating of the graphene oxide resulting in deoxygenation to graphitic carbon. Using a transmission electron microscope grid as a mask, the grid pattern can be transferred to a graphene oxide film.

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We present a differential modulation technique which is effective in extracting the photoreflectance from GaAs/AlxGa1−xAs samples exhibiting excessive room-temperature photoluminescence. Using the technique, we obtain the photoreflectance from the triangular potential-well region of a high-electron-mobility transistor. Surprisingly, the signal from the potential well can be extracted from underneath two layers of heavily doped material, making differential photoreflectance useful in detection of two-dimensional electron gas in high-electron-mobility transistors cladded with doped protective GaAs caps which usually obliterate the PR from the buried interfaces. We isolate absorptionlike photoreflectance peaks at 1.447 and 1.472 eV and show that their energies and the ratio of their amplitudes agree with the 2DEG theory for asymmetric triangular potential well.

An experimental study has been conducted to explore the coupling between a coaxial gaseous hydrogen / liquid oxygen jet flame and transverse acoustic perturbations. A variety of chamber conditions including acoustic frequency, amplitude, and the location of the pressure node / antinode with respect to the flame were examined. The flame response was documented using high-speed imaging including backlit visualization and unfiltered chemiluminescence. Dynamic mode decomposition was used to isolate the spatial structure of the flame response at the forcing frequency. The results indicate that the flame response to forcing is qualitatively similar to previous results of nonreacting coaxial jet flows; the pressure node forcing appears to generate in-plane flapping of the flame while pressure antinode forcing induces a helical structure in the flame.

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