a texas a&m university physicist is developing a technique to identify molecules on the surfaces of metals which could have far-reaching implications in the control of chemical reactions in operations within the chemical and petroleum industries it is possible to get images of molecules today with the scanning tunneling microscope (stm) but until recently it has been impossible to identify the molecules in these images says glenn agnolet a texas a&m physicist who is part of a team doing research on the stm at texas a&m the stm has been an enormous revolution for surface science adds agnolet before the advent of the stm surface scientists used probes to determine the molecule positions averaged over a large sample with the stm scientists can obtain local information on the atomic scale like a phonograph the stm uses a tiny needle that follows the bumps and troughs on the surface of a material giving an image of what this surface looks like as the needle approaches the surface an electrical current flows from the needle to the metallic surface since the current depends on the distance the current variations reflect the topography of the surface the surface of a material is like a landscape made of mountains and valleys agnolet says the stm can detect these changes of elevation and make a topography of the surface although molecules are revealed by the change of topography until recently scientists have been unable to identify the molecules with the stm you get these beautiful pictures says agnolet but the question remains: ‘what am i really looking at in an attempt to identify molecules agnolet is using self-assembled tunnel junctions (satjs) a device developed by stephen gregory a low temperature physicist at the university of oregon an satj is made of two long fine metallic wires with a layer of neon in between the first metallic wire plays the role of the stms needle the second wire the role of the stms surface and the neon layer acts to keep the two surfaces apart if a molecule sits between the two metal surfaces then as the electrons flow from one metal to the other they can cause the molecule to vibrate every molecule has vibrational modes that can be used to distinguish it from other molecules says agnolet from a study of acetylene molecules on platinum agnolet found that the coupling between the molecule and the electrons is ten times larger than expected by understanding the mechanisms of this effect he hopes to be able to identify more complex molecules to improve his measurements agnolet is now studying undesirable effects due to imperfections and defects on the wires the biggest problem is that we do not see the same thing every time says agnolet so we are trying to find the dominant behavior as opposed to materials problems we take lots of data and we try to sift out of this data the underlying features that we are interested in agnolet has published his results in the journals applied physics letters and physica the ultimate goal is to be able to take a metallic surface to add molecules to it and then to be able to find those molecules on the surface with an stm type of instrument agnolet says contact: glenn agnolet (979) 845 – 2386 or agnolet@physicstamuedu aggiedaily office of university relations texas a&m university (979) 845-4641