A new method is reported for deflecting a microscopic jet emanating from a nozzle away from the nozzle’s axis of symmetry. It relies on putting energy into the jet through an asymmetric heater embedded in the nozzle. This novel phenomenon is probed theoretically. It is shown that jet deflection is set by the competition among three effects. Two of these can be attributed to the variation with temperature of surface tension and the third to that of viscosity. Whether the contact line is fixed or free is shown to profoundly impact the extent of jet deflection at a given flow rate.

We have experimentally determined the equation of state of a two-dimensional "gas" of pentadecylic-acid molecules moving on the surface of water. Our data provide conclusive evidence for the occurrence of a phase transition in this two-dimensional system, similar to the liquid-vapor transition displayed by three-dimensional pure fluids. We have demonstrated the existence of a critical point, determined the shape of the coexistence curve, and observed an increase in the isothermal compressibility near the critical point.

We report observations of the effect of heat pulses on the precipitation of oxygen in single-crystal silicon. In our experiments, heat pulses are applied for various durations at a fixed temperature of 1200 °C prior to a two-step precipitation sequence. When no pulse is applied, precipitation is at a maximum and is close to that expected from considerations of solid solubility, provided account is taken of the loss of oxygen due to evaporation. For very short pulses (e.g., 2 s), precipitation is suppressed by several fold. As the length of the pulse is increased to roughly 100 s, the precipitation recovers to its initial value. For very long pulses (greater than 10 000 s), precipitation decreases to nearly zero. There are no further changes in the precipitation characteristics for pulse times up to 50 000 s. We interpret these results in terms of a model in which the thermal pulses modify an initial distribution of heterogeneous nucleation sites. The fraction of heterogeneous sites that survive the two-step precipitation cycle is assumed to decrease continuously during the pulse due to thermal dissolution of sites. For short pulses, the decrease in sites accounts for the suppressed precipitation. For longer pulse times (about 100 s), we believe the recovery of precipitation is due to a reduction by out-diffusion of silicon self-interstitials which otherwise limit the rate of precipitation. For very long pulses (10 000 s), all nuclei have dissolved, so that negligible precipitation occurs. This interpretation is supported by experiments in which the interstitial population is altered by changes in ambient and by experiments in which the effects of more complex pulse sequences are investigated. It is suggested that studies of this type can be used to characterize the defect population of silicon for device applications as well as to investigate precipitation processes.

We have measured the spectrum of light scattered inelastically from thermal excitations on the surface of liquid xenon near its critical point, deduced the temperature dependence of the surface tension a and the effective kinematic viscosity F, examined the Fisk-Widom relation between the surface tension and the long-range correlation length £, and obtained numerically the Kawasaki critical contribution to the thermal diffusivity. The surface tension and the effective kinematic viscosity along the coexistence curve may be represented by CT = (62.9±1.8)(1 -T/T c ) um ± °-m dyn/cm and F= [448 + 12(T c -T)] ±15 micro stokes.We have measured the surface tension o and the effective kinematic viscosity v of xenon along its coexistence curve in the temperature range 0.070°K < T c -T< 5°K by using the techniques of optical mixing spectroscopy 1 to observe the spectrum of light scattered inelastically from thermal excitations on the liquid-vapor interface. 2 " 4 We have found that over this entire temperature range the surface tension obeys the power law cr = (62.9±1.8)(l -T/r/-302 * 0 -006 dyn/cm (1) and that the effective kinematic viscosity is slowly varying along the coexistence curve:v= [448 + 12(T C -T)} ± 15 microstokes.(2)Using these results, we have examined the Fisk-Widom relation 5 which predicts that the scaled interfacial thickness L', defined by the equation c P 2 (Pi-P v ) 2