Tip shape dependence of the light emission efficiency for the scanning tunneling microscope

Abstract

We have investigated the relation between the scanning-tunneling-microscope (STM) tip shape and the efficiency of STM light emission. The light intensity radiated by a current source placed in the tip-sample gap of the STM was calculated for various shapes of the tip using the finite differential time domain method. We found that the highest emission efficiency is obtained for the pyramidal tip with the flat top of 4 nm width and the apex angle of 90 °C.

Creation and Luminescence of a Single Silver Nanoparticle on Si(111) Investigated by Scanning Tunneling Microscopy

“…This is similarly seen in the previous result, i.e., the calculation of the STM-LE from the Au substrate with the W tip. 51,52,57 The tip size dependence observed in the radiation intensity is ascribed to the periphery effect; i.e., the part of light emitted from the tip−sample gap is blocked due to the presence of the STM tip. One can expect that the radiation intensity should be reduced with the tip radius above the certain critical value.…”

“…Although this method allows us to reproduce various types of experimental STM-LE results, it is only applicable to the system consisting of simple layered structures. In contrast, the FDTD method has been recently applied to the spectral analysis of the STM-LE. , One of the advantages of the FDTD is that the electromagnetic calculations can be performed for the sample with the arbitrary shapes. Recently, it was confirmed that the FDTD calculation provides predictions which are consistent with those of the calculation based on the dielectric theory .…”

Vibrational Excitation of a Single Benzene Molecule Adsorbed on Cu(110) Studied by Scanning Tunneling Microscope Light Emission Spectroscopy

“…27 It may be claimed that the observed difference can be explained merely by the effect of the STM tip. We investigated this possibility by performing the same experiment with different STM tips.…”

“…Note that the shape of the STM tip is known to affect the shape of the STM-LE spectrum as well as the intensity of the STM-LE. 27 It may be claimed that the observed difference can be explained merely by the effect of the STM tip. We investigated this possibility by performing the same experiment with different STM tips.…”

Note: Optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence

“…That is partly why early photon mapping for molecular systems was usually acquired with large currents (nA typically, 5 with only a couple of recent examples 6, 7 going down to sub-nA) and long integration time (dozens of milliseconds per pixel). The STM induced luminescence is known very sensitive to the tip status, 6,14 experiments carried out at high currents may modify both molecules on surfaces and tip conditions easily, while long integration time would require a very stable cryogenic system to avoid the thermal a) Author to whom correspondence should be addressed. Electronic mail:…”