A method for characterizing carbon nanotubes comprising: providing a conductive substrate and applying an insulating layer on the conductive substrate; forming a carbon nanotube structure on a surface of the insulating layer, the carbon nanotube structure includes at least one carbon nanotube; placing the carbon nanotube structure under a scanning electron microscope, adjusting the scanning electron microscope with an accelerating voltage ranging from 520 KV, a dwelling time ranging 620 microseconds and a magnification ranging from 10000100000 times; taking photos of the carbon nanotube structure with the scanning electron microscope; and, obtaining a photo of the carbon nanotube structure, the photo shows the at least one carbon nanotube and a background.

The invention provides novel gold nanoclusters of the formula Au.sub.20(SR).sub.15(weak ligand), wherein each R is independently an organic group, and the weak ligand is a weakly associating gold ligand of Formula I as described herein. The nanocluster can have an approximate molecular weight of 6 kDa. Corresponding dimers of the nanocluster can have an approximate molecular weight of 10 kDa (by SEC). The invention also provides methods of making and using the gold nanoclusters.

A machine-readable medium and methods of reading and writing same are disclosed. The machine-readable medium comprises a substrate having an array of addressable locations thereon, each addressable location adapted to be physically associated with a collection of non-polymeric molecules. The molecules in each collection are selected from a set of unambiguously identifiable molecules, each molecule uniquely associated with a predetermined position in a numerical value, wherein the presence of the molecule in the collection indicates a predetermined digit at the associated position and the absence of said molecule in the collection indicates a zero at said associated position.