Temperature tunneling

The temperature-dependent fluctuation rates a>i2 of the EFG, which result from this simultaneous fit, were interpreted in terms of low-temperature tunneling plus a temperature-dependent activation of the terminal O-atom from position 1 to 2 and vice versa, described by the expression... 

Ironically, the most recent calculational treatments of the rearrangement from 56 to 57 indicate that even at room temperature tunneling does, in fact, dominate the H-shift process. Phenyl substitution in 56 should lower the energy barrier for rearrangement compared with 54, not only increasing the rate of classical rearrangement... 

J. T. Fermann and S. Auerbach, Modeling proton mobility in acidic zeolite clusters II. Room temperature tunneling effects from semiclassical theory, J. Chem. Phys. 112 (2000), 6787. 

Santos TS, Lee JS, Migdal P, Lekshmi IC, Satpati B, Moodera JS (2007) Room temperature tunnel magnetoresistance and spin-polarized tunneling through an organic semiconductor barrier. Phys Rev Lett 98 016601... 

Although there is no macroscopic conduction in localized states at zero temperature, tunneling transitions occur between localized states and give rise to conduction at elevated temperatures. The spatial extent of the wavefunction allows tunneling between neighboring localized states as illustrated in Fig. 1.10 for two states of separation R and energy difference The probabilities of twineling between states 1 and 2, and vice versa are respectively. 

Low temperature tunneling thermalization in the band tail is observed by time resolved luminescence, which is a transition between band tail electrons and holes, as described in Section 8.3.2. Fig. 8.11 (a) shows the change in energy of the luminescence peak with increasing time after the excitation pulse, measured at 12 K. The decrease of the energy at times up to 10" s is caused by carrier thermalization - the changes at... 

Here we show how one particular model, the free-volume model, can account for the glass transition, the behavior of ij, C, and t near Tg, and the existence of low-temperature tunneling states. 

Findings of bacterial attack in wood exposed at the bottom of the Baltic Sea suggest that active degradation occurs at rather low temperatures. Tunneling bacteria in laboratory experiments have been found to attack wood at 40°C but not at 45°C. A different form of bacterial attack was observed at 70°C. 

Reaction dynamics in acidic zeolites room temperature tunneling effects... 

At lower temperatures, tunneling currents may become more important. The tunneling of electrons from the conduction band into the metal is certainly observed in crystalline Si and has been reported for amorphous Si (Alkaisi and Thompson, 1979-1980). The process is more complicated in a-Si H because the localized states near the conduction-band tail may significantly enhance the tunneling current. 

Singh, Jag J. Davis, William T. and Puster, Richard L. Proposed Fast-Response Oxygen Monitoring and Control System for the Langley 8—Foot High—Temperature Tunnel. NASA TP—2218 (1983). 

---