We present novel measurements of the primary instabilities of thin liquid films flowing down an incline. A fluorescence imaging method allows accurate measurements of film thickness h(x, y, t) in real time with a sensitivity of several microns, and laser beam deflection yields local measurements with a sensitivity of less than one micron. We locate the instability with good accuracy despite the fact that it occurs (asymptotically) at zero wavenumber, and determine the critical Reynolds number Rc for the onset of waves as a function of angle β. The measurements of Rc(β) are found to be in good agreement with calculations, as are the growth rates and wave velocities. We show experimentally that the initial instability is convective and that the waves are noisesustained. This means that the waveform and its amplitude are strongly affected by external noise at the source. We investigate the role of noise by varying the level of periodic external forcing. The nonlinear evolution of the waves depends strongly on the initial wavenumber (or the frequency f). A new phase boundary f*s(R) is measured, which separates the regimes of saturated finite amplitude waves (at high f) from multipeaked solitary waves (at low f). This boundary probably corresponds approximately to the sign reversal of the third Landau coefficient in weakly nonlinear theory. Finally, we show that periodic waves are unstable over a wide frequency band with respect to a convective subharmonic instability. This instability leads to disordered two-dimensional waves.

We present experimental results for Rayleigh-Bénard convection with rotation about a vertical axis at dimensionless rotation rates 0 ≤ Ω ≤ 250 and ǫ ≡ ∆T /∆Tc − 1 < ∼ 0.2. Critical Rayleigh numbers and wavenumbers agree with predictions of linear stability analysis. For Ω > ∼ 70 and small ǫ the patterns are cellular with local four-fold coordination and differ from the theoretically expected Küppers-Lortz-unstable state. Stable as well as intermittent defect-free square lattices exist over certain parameter ranges. Over other ranges defects dynamically disrupt the lattice but cellular flow and local four-fold coordination is maintained.

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Organic compounds with selective near‐infrared absorption and visible transparency are very desirable for fabrication of transparent/semitransparent optoelectronic devices. Herein, we develop a molecule with selective near‐infrared absorption property, QBNA‐O, in which four B←N units are incorporated to the core and two benzodioxin groups are introduced at the termini of the dibenzo‐azaacene skeleton. QBNA‐O exhibits a small optical gap of 1.39 eV due to the strong electron‐donating benzodioxin groups and the strong electron‐withdrawing B←N units. In toluene solution, QBNA‐O shows a strong absorption peak at 856 nm with the full width at half maximum (FWHM) of only 41 nm as well as very weak absorption in the visible range from 380 nm to 760 nm. Thin films of QBNA‐O exhibit the average visible transparency (AVT) of 78 % at the thickness of 205 nm and 90 % at the thickness of 45 nm. Solution‐processed organic field‐effect transistors (OFETs) of QBNA‐O display ambipolar transporting behavior with the electron mobility of 0.52 cm2 V−1 s−1 and the hole mobility of 0.013 cm2 V−1 s−1 together with excellent air‐stability. The selective NIR absorbing property and excellent charge transporting property imply that QBNA‐O can be used to fabricate transparent organic optoelectronic devices.