Distance tunneling spectroscopy

The STM imaging resolution is mainly determined by the tunneling mechanism, which may be identified by distance tunneling spectroscopy (DTS). DTS is characterized by measuring the tunneling current, U, as a function of the tip-substrate distance, d, at constant tunnel voltage Et. For ex-situ measurements is the applied... 

Nagy G, Wandlowski T (2003) Double layer propoties of Au(lll)/H2S04 (Cl) + Cu2+ fiom distance tunneling spectroscopy. Langmuir 19 10271-10280... 

The ESTM experiment provides actually five measurable quantities tunnelling current, / at the applied voltage, U, and three dimensions, x, y, z. The standard STM can therefore easily be modified by recording the local l-Uy U-zy or /-z characteristics (z is vertical distance of the tip from the electrode surface). Plot of dl/dU or d//dz versus x and y brings additional information on the electronic and chemical surface properties (local work functions, density-of-states effects, etc.), since these manifest themselves primarily as l-U dependences. The mentioned plots are basis of the scanning tunnelling spectroscopy (STS). 

Gopakumar TG, Meiss J, Pouladsaz D, Hietschold M (2008) HOMO-LUMO gap shrinking reveals tip-induced polarization of molecules in ultrathin layers tip-sample distance-depen-dent scanning tunneling spectroscopy on d8 (Ni, Pd, and Pt) phthalocyanines. J Phys Chem C 112 2529-2537... 

It is possible to obtain chemical information from STM when it is used in the spectroscopic mode, for example by measuring at a fixed distance the tunneling current / as a function of the voltage over the gap (I/V spectroscopy). This method of measurement is called scanning tunneling spectroscopy (STS) [49],... 

Fig. 14.3. Dependence of local tunneling spectra with distance. By moving a tip with atomic resolution closer and closer to the sample surface, the features in the tunneling spectra is broadened. At the contact point, the tunneling spectrum becomes featureless. This phenomenon demonstrates the effect of local modification of the sample wavefunction and the consequence of uncertainty principle in scanning tunneling spectroscopy. (After Avouris et al., 1991b.)...

Tip-state effects 19—20, 126, 297 atomic resolution, and 32 corrugation enhancement 125 corrugation inversion, and 137 graphite, and 146 layered materials, on 20 metal surfaces, on 19 scanning tunneling spectroscopy, and 24, 308 Tip-sample distance 53... 

Spectroscopic techniques Scanning Tunneling Spectroscopy (STS) Frequency-Distance Curves Force-Distance Curves Phase- Distance Curves Full-resonance Spectroscopy Adhesion Force Spectroscopy Amplitude-Distance Curves I(z) Spectroscopy I(v) Spectroscopy... 

Fundamentals. The tunneling current depends at fixed voltage across the gap between tip and probed surface on the distance and the local probability of electron transfer. This in turn is a function of local electron density, work function or related localized electronic properties (for an overview of tunneling spectroscopies. 

Artes JM, Diez-Perez I, Sanz F, Gorostiza P (2011) Direct measurement of electron transfer distance decay constants of single redox proteins by electrochemical tunneling spectroscopy. ACS Nano 5 2060-2066... 

ANanoScope I (Digital Instruments, CA) was modified to carry out the electrochemical tunneling spectroscopy (ETS) measurement. ETS measurement was carried out by monitoring the tunneling current under a constant tip-sample distance. Details of the present ETS system were desaibed elsewhere (7). The potential of the tip and the sample were controlled independently by a home-built bi-potentiostat (8) with respect to a common Pd-H reference electrode which was charged sufficiently at a current density of 10 fcA cm before each measurement Potentials were presented with respect an Ag/AgCl electrode in this article. The counter electrode was a Pt wire. The tip was a simply cut Pt wire (0.3 mm) insulated with apiezon wax. 

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