Quantum Tunnelling in Enzyme-Catalysed Reactions

2009 ◽  
Keyword(s):  
Quantum Tunnelling

Microscopic Interpretation of Arrhenius Parameters

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Transition State Theory ◽  
Average Energy ◽  
Zero Point ◽  
State Theory ◽  
Exponential Factor ◽  
Quantum Tunnelling ◽  
Microscopic Interpretation ◽  
The Difference

This chapter reviews the microscopic interpretation of the pre-exponential factor and the activation energy in rate constant expressions of the Arrhenius form. The pre-exponential factor of apparent unimolecular reactions is, roughly, expected to be of the order of a vibrational frequency, whereas the pre-exponential factor of bimolecular reactions, roughly, is related to the number of collisions per unit time and per unit volume. The activation energy of an elementary reaction can be interpreted as the average energy of the molecules that react minus the average energy of the reactants. Specializing to conventional transition-state theory, the activation energy is related to the classical barrier height of the potential energy surface plus the difference in zero-point energies and average internal energies between the activated complex and the reactants. When quantum tunnelling is included in transition-state theory, the activation energy is reduced, compared to the interpretation given in conventional transition-state theory.

scholarly journals Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Longhua Tang ◽  
Binoy Paulose Nadappuram ◽  
Paolo Cadinu ◽  
Zhiyu Zhao ◽  
Liang Xue ◽  
...  
Keyword(s):  
Limited Range ◽  
Practical Implementation ◽  
Successful Operation ◽  
Detection Rates ◽  
Quantum Tunnelling ◽  
Conductive Substrate ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Transport Molecules ◽  
Magnitude Increase

AbstractQuantum tunnelling offers a unique opportunity to study nanoscale objects with atomic resolution using electrical readout. However, practical implementation is impeded by the lack of simple, stable probes, that are required for successful operation. Existing platforms offer low throughput and operate in a limited range of analyte concentrations, as there is no active control to transport molecules to the sensor. We report on a standalone tunnelling probe based on double-barrelled capillary nanoelectrodes that do not require a conductive substrate to operate unlike other techniques, such as scanning tunnelling microscopy. These probes can be used to efficiently operate in solution environments and detect single molecules, including mononucleotides, oligonucleotides, and proteins. The probes are simple to fabricate, exhibit remarkable stability, and can be combined with dielectrophoretic trapping, enabling active analyte transport to the tunnelling sensor. The latter allows for up to 5-orders of magnitude increase in event detection rates and sub-femtomolar sensitivity.

Quantum mechanical tunnelling: the missing term to achieve sub-kJ mol−1 barrier heights

2021 ◽  
Author(s):  
Sebastian Kozuch ◽  
Tim Schleif ◽  
Amir Karton
Keyword(s):  
Barrier Height ◽  
Quantum Mechanical ◽  
Effective Barrier Height ◽  
Quantum Tunnelling ◽  
Barrier Heights ◽  
Effective Barrier

Quantum tunnelling can lower the effective barrier height, creating a discrepancy between experiment and theory.

Asymmetrically-gated graphene self-switching diodes as negative differential resistance devices

Nanoscale ◽  
2014 ◽  
Vol 6 (13) ◽  
pp. 7628-7634 ◽  
Author(s):  
Feras Al-Dirini ◽  
Faruque M. Hossain ◽  
Ampalavanapillai Nirmalathas ◽  
Efstratios Skafidas
Keyword(s):  
Negative Differential Resistance ◽  
Differential Resistance ◽  
Conduction Current ◽  
Quantum Tunnelling ◽  
Tunnelling Current

In an asymmetrically-gated graphene self-switching diode the quantum tunnelling current is used to control a much larger channel conduction current, resulting in a very pronounced NDR effect.

Neural network approach to modelling the behaviour of quantum tunnelling composites as multifunctional sensors

2010 ◽  
Vol 19 (12) ◽  
pp. 125007 ◽  
Author(s):  
Andrés Díaz Lantada ◽  
Pilar Lafont Morgado ◽  
Javier Echavarri Otero ◽  
Juan Manuel Munoz-Guijosa ◽  
José Luis Muñoz Sanz
Keyword(s):  
Neural Network ◽  
Network Approach ◽  
Neural Network Approach ◽  
Quantum Tunnelling
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