Quantum tunneling spectroscopy

Bakkers EP, Hens Z, Kouwenhoven LP, Gurevich L, Vanmaekelbergh D (2002) A tunneling spectroscopy study on the single-particle energy levels and electron-electron interactions in CdSe quantum dots. Nanotechnology 13 258-262... 

Field emission is a tunneling phenomenon in solids and is quantitatively explained by quantum mechanics. Also, field emission is often used as an auxiliary technique in STM experiments (see Part II). Furthermore, field-emission spectroscopy, as a vacuum-tunneling spectroscopy method (Plummer et al., 1975a), provides information about the electronic states of the tunneling tip. Details will be discussed in Chapter 4. For an understanding of the field-emission phenomenon, the article of Good and Muller (1956) in Handhuch der Physik is still useful. The following is a simplified analysis of the field-emission phenomenon based on a semiclassical method, or the Wentzel-Kramers-Brillouin (WKB) approximation (see Landau and Lifshitz, 1977). 

The local modification of sample wavefunctions due to the proximity of the tip, and consequently the involvement of the Bloch functions outside the energy window Er eV in the tunneling process, has an effect on the limit of the energy resolution of scanning tunneling spectroscopy. This effect is discussed in detail by Ivanchenko and Riseborough (1991). First, if the tunneling current is determined by the bare wavefunctions of the sample and the tip, the process is linear, and there is no effect of quantum uncertainty. The effect of quantum uncertainty is due to the modification or distortion of the sample wavefunction due to the existence of the tip. Here, we present a simple treatment of this problem in terms of the MBA. 

In parallel, the related activity was in the field of single-electron shuttles and quantum shuttles [143-153]. Finally, based on the Bardeen s tunneling Hamiltonian method [154-158] and Tersoff-Hamann approach [159,160], the theory of inelastic electron tunneling spectroscopy (IETS) was developed [113-116,161-163],... 

In parallel, the theory of inelastic scanning tunneling spectroscopy was developed [113-116,161-163], For a recent review of the electron-vibron problem and its relation to charge transport at the molecular scale see Ref. [164], Note the related problem of quantum shuttle [143,145,147,149],... 

Tunnelling spectroscopy is unique to observing quantum nonlinear dynamics in crystals. Evidence for proton transfer along hydrogen bonds is another outstanding contribution of INS. It is another manifestation of the decoupling of proton dynamics from the crystal lattice. The quantum nature of proton transfer dynamics even at room temperature is quite unforeseen and contrasts with mechanisms based on semiclassical diffusion jumps. 

XRD, Elemental Analysis, NMR, UV-vis, and STM. STM images of InAs give particle size distributions and confirm sample conductivity. Scanning tunneling spectroscopy shows a larger bandg for nanocrystsd-line InAs than for InAs wafers, consistent with quantum confinement. 

The combined approach of low-temperature scanning tunneling spectroscopy and DFT computations (LDA and HSE periodic computations) was used to study hexadecafluoro-phthalocyanine CuFjgPc and epitaxial graphene on 6H-SiC(0001) (Table 11.9) [154]. Since a dispersion-stabilized system was investigated, computational quantum chemistry methods that properly treat vdW-interactions were desired for such a study. These may correct the computed adsorption- and diffusion-related energetic characteristics. 

Firstly, we showed that the quantum fluctuation and tunneling may be simulated when among the Michaelis-Menten also the logistic kinetics and its solution is considered, a feature confirmed by applying the Beer-Eambert law of absorption spectroscopy. Such picture is in accordance with the observed enhanced rate of the vibrationally states of ES by means of quantum tunneling when considered within the Brownian mechanism (1.168) and Figure 1.13. 

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