Tunneling modes

Takahashi S, Futamata M and Ko]ima I 1999 Spectroscopy with scanning near-field optical microscopy using photon tunnelling mode J. Microscopy 194 519... 

Picardi, G., Nguyen, Q., Schreiber, J. and Ossikovski, R. (2007) Comparative study of atomic force mode and tunneling mode tip-enhanced Raman spectroscopy. Eur. Phys. J. Appl. Phys., 40, 197-201. 

An approximate analytical solution (see above) yields that Tc is nearly independent of the tunnel mode frequency. Experimentally, it is found that in H2-xDxSQ substantial variations in take place with variations in x [54]. This fact does not contradict the above results since the tunnel mode is renormalized through the coupling C as -/q (S ) - (S > /g4T). As C... 

Besides the peaks of the local proton modes typical for hydrogen bond, a sharp peak at 28 meV was observed in KDP [34] and attracted much attention [34,38,39]. This peak exists in DKDP at somewhat higher frequency its intensity decreases in both crystals and its width decreases upon the transition from the FE to the PE phase, without any softening of its frequency [38]. Hence, it is concluded that this mode is connected with the phase transition dynamics, i.e., coupled to the polarization fluctuations. This mode is not the tunneling mode or any local mode of proton or deuteron, but rather some collective optical mode of the lattice that involves substantial proton or deuteron displacement. It has been suggested [38] that this mode corresponds to the mode that has a peak at about 200 cm (25 meV) in Raman scattering and infrared reflectivity spectra, and that it is coupled to the soft mode and usually... 

In reactions with the participation of H atoms, both classical (overbarrier) and quantum (underbarrier, tunneling) modes of overcoming an activation barrier are possible. The value of the isotope effect suggests that the reaction occurs via a classical (overbarrier) path at room temperature. Assuming a normal value of the pre-exponential factor (10-11 cm3/molecule sec) for the activation energy of this reaction, we obtain E — 7.7 (8.7)kcal/mol (processes with the participation of H2(D2) molecules). 

The total tunneling current then consists of a resonance tunneling current and the direct elastic current. These two currents are shown plotted separately in Figs. 56 and 57 and it can be seen that the most important qualitative result is that the resonance tunneling mode gives a maximum in the current distribution, though this maximum may be difficult to observe in practice. 

Fig. 2.15. Temperature dependence of the heat capacity fitted to the form of Eq. (2.22). The shaded region represents the excess heat capadty from the tunneling modes (Graebner et at. 1984).

Results obtained with n-GaAs in NaOH are presented in Fig. 17. True in-situ STS measurements, plotted in the form of ii - U, curves, are solid lines. Since in tunneling mode the tip current is the sum ij + h, with ij the tunnel current, the faradaic component ip has been determined by retracting the tip far away from the surface (dotted line). The shape of STS curves is very similar to curves obtained in ex-situ... 

The tunneling modes in a-MnH are found to be suppressed by elastic stresses [128]. In fact, the INS peak due to tunneling disappears at a pressure of 0.8 GPa in a quasi-hydrostatic regime of a sapphire anvil cell. On the other hand, the appli-... 

Figure 29.19 The reactant (R), transition state (TS) and product (P) configurations for the rate-determining triple proton transfer step of the 58-atom model used to represent the active site of carbonic anhydrase II [18]. The numbers denote bond distances (in A) calculated at two different levels of theory. The arrows in the insert figure represent the tunneling mode and illustrate the degree of synchronicity of the transfer.

Dissociative Recombination Crossing and Tunneling Modes, David R. Bates... 

Figure 7.9. Types of the SNOM configurations, (a) Transmission coiiection mode. The tip is generaiiy metaiiized except for its nano-sized end. (b) Transmission iiiu-mination mode, (c) Refiection coiiection mode, (d) Photon scanning tunnei mode. The iiiumination beam is totaiiy refiected inside a substrate, (e) Duai iiiumination coiiection mode. It is a combination of (a) and (b). (f) Refiection illumination mode, it is an inverted photon tunnel mode (d) [53].

Moreover, among SNOM modifications operating in the collection mode, there is a so-called photon scanning tunnel mode, where light is incident at the angle of total internal reflection (Figure 7.9d). The optical near field localized in the neighborhood of the specimen surface is detected with a near-field probe. 

S. Takahashi, M. Futamata, and 1. Koji-ma. Spectroscopy with Scanning Near-Field Optical Microscopy Using Photon Tunnelling Mode, J. Microsc. Oxford 194, 519 (1999)... 

S Takahashi, M Futamata, I Kojima. Spectroscopy with scanning near-held optical microscopy using photon tunnelling mode. J Microsc (Oxford) 194 519-522, 1999. 

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