A new nanoscale effect caused by adsorbed molecules
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Scientists from Max Plank and EPFL have discovered a new nanoscale effect in the interplay between a quantized metallic system and adsorbed molecules.
The study, published in Physical Review Letters, uses STM conductance spectroscopy and mapping to analyze the impact of molecular adsorption on the quantized electronic structure of individual metal nanoparticles. The work is a collaborative effort between the Fritz-Haber-Institute of the Max-Planck-Society in Berlin and Wolf-Dieter Schneider at EPFL’s Institute of Condensed Matter Physics.
The researchers adsorbed isophorone and CO2 onto monolayer gold islands grown on MgO thin-films. Isophorone and CO2 acted as prototypes for physisorptive and chemisorptive binding, respectively on the metal-oxide boundary.
The study found that CO2 binding causes the gold quantum well states to increase their mutual energy spacing. On the other hand, they move together for isophorone physisorption. In effect, the experiment reveals how molecular adsorption affects individual quantum systems, which is “of utmost relevance for heterogeneous catalysis.”
Reference
Stiehler C, Calaza F, Schneider W-D, Nilius N, Freund H-J. Molecular Adsorption Changes the Quantum Structure of Oxide-Supported Gold Nanoparticles: Chemisorption versus Physisorption.Phys Rev Lett 115, 036804, 14 July 2015. DOI: http://dx.doi.org/10.1103/PhysRevLett.115.036804