Photon emission at molecular resolution induced by a scanning tunneling microscope

The tip-surface region of a scanning tunneling microscope (STM) emits light when the energy of the tunneling electrons is sufficient to excite luminescent processes. These processes provide access to dynamic aspects of the local electronic structure that are not directly amenable to conventional STM experiments. From monolayer films of carbon-60 fullerenes on gold(110) surfaces, intense emission is observed when the STM tip is placed above an individual molecule. The diameter of this emission spot associated with carbon-60 is approximately 4 angstroms. These results demonstrate the highest spatial resolution of light emission to date with a scanning probe technique.     

New cell wall and cell lumen wood polymer composites

Summary Furfuryl alcohol-based (FA) cell wall and methyl methacrylate-based (MMA) combination formulations were used to make wood polymer composites (WPC). Swelling gradients developed during preparation. Properties (density, hardness, water extractables, antiswell efficiency) gradients were observed along samples in 5 of the 7 treating formulations. Two cell wall treatments based on furfuryl alcohol did not show the gradients. The results suggest treating solution separations occurred during impregnation and the resulting nonhomogenious chemical produced the properties gradients. WPC made using the combination formulations based on MMA had properties which fell between cell wall and cell lumen formulations.It is gratefully acknowledged that Mr. Michel Andrew, Student Assistant, carried out the experiment part of this study