Tunneling electron induced luminescence from monolayered Cu-TBP porphyrin molecules adsorbed on Cu(100)

STM-induced luminescence spectra from a monolayer of Cu-TBP porphyrin molecules indicate purely plasmon-mediated emission from the Cu(I 0 0) substrate. The molecule appears to enhance the emission intensity, but no direct luminescence from the molecules was observed. Such observation suggests the role of molecules acting mainly as a spacer to modify the junction geometry, specifically, increasing the tip-substrate distance to cause blue-shift of emission. (C) 2003 Elsevier Science B.V. All rights reserved.