Light emission scanning tunneling microscopy

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The light-emission scanning tunneling microscopy ( English light emission scanning tunneling microscopy , LE-STM ) is a modification of the scanning tunneling microscopy , the first of Coombs et al. has been described. LE-STM enables the observation and investigation of electronic relaxation via light emission on surfaces at the atomic level.

Measuring principle

Electrons are injected into a surface via a tunnel tip . The tunneling electrons can generate surface plasmons in the area of ​​the tunnel contact. The tunnel tip and sample surface form a kind of resonator, so that the properties of the plasmons induced by the tunnel electrons also depend on the dielectric properties of this “resonator” and its shape (especially the shape of the tunnel tip). In addition to these so-called tip-induced plasmons ( English tip induced plasmon , TIP) are also other light generating mechanisms discussed in the literature such as surface-enhanced Raman scattering or two-electron processes (similar to the Auger effect ).

application

The investigation of relaxation channels from the light emission provides important information about the electronic structure of surfaces and supplements existing scanning tunnel spectroscopic measurements. For example, Fermi's golden rule could be verified in real space through LE-STM experiments. Thus, the LE-STM makes important contributions to the understanding of electronic processes on surfaces.

literature

  • R. Berndt: Photon Emission from the Scanning Tunneling Microscope In: R. Wiesendanger (Ed.): Scanning Probe Microscopy . Springer, New York 1998, ISBN 978-3-642-08360-0 , pp. 97-134.

Individual evidence

  1. ↑ JH Coombs, JK Gimzewski, B. Reihl, JK Sass and RR sledders: photon emission experiments with the scanning tunneling microscope . In: J. Microsc. tape 156 , no. 2 , November 1988, pp. 325–336 , doi : 10.1111 / j.1365-2818.1988.tb01393.x .
  2. ^ P. Johansson, R. Monreal and P. Apell: Theory for light emission from a scanning tunneling microscope . In: Physical Review B . tape 42 , no. 14 , November 15, 1990, pp. 9210 , doi : 10.1103 / PhysRevB.42.9210 .
  3. ↑ J. Aizpurua, SP Apell and R. Berndt: Role of tip shape in light emission from the scanning tunneling microscope . In: Physical Review B . tape 62 , no. 3 , June 15, 2000, p. 2065 , doi : 10.1103 / PhysRevB.62.2065 .
  4. ↑ R. Pechou, R. Coratger, F. and J. Ajustron Beauvillain: Cutoff anomalies in light Emitted from the tunneling junction of a scanning tunneling microscope in air . In: Applied Physics Letters . tape 72 , no. 6 , 1998, pp. 671 , doi : 10.1063 / 1.120841 .
  5. ^ G. Hoffmann, R. Berndt and P. Johansson: Two-Electron Photon Emission from Metallic Quantum Wells . In: Physical Review Letters . tape 90 , no. 4 , January 28, 2003, p. 046803 , doi : 10.1103 / PhysRevLett.90.046803 .
  6. ↑ Chi Chen, CA Bobisch and W. Ho: Visualization of Fermi's Golden Rule Through Imaging of Light Emission from Atomic Silver Chains . In: Science . tape 325 , no. 5943 , September 21, 2009, p. 981-985 , doi : 10.1126 / science.1174592 .