630
A. P. Pospelov et al.
large diameters of the conduction channel, while high resistances are those of the
contacts with small diameters, down to the size of an atom [3]. The steps in the curve
R(t) (Fig. 1b) reflect the existence of metastable quantum energy states of contacts
with certain diameters [10], which emerge in the process of the contacts’ evolution.
The process of the cyclic switchover effect can be thought of as follows. As the
current starts flowing through the needle tip, a dendrite starts growing along the
lines of force of the electric field toward the “anvil” (precommutation phase) [3].
Sometime later the dendrite tip reaches the surface of the counterelectrode. In the
point of contact, a dendritic Yanson point contact is formed (commutation phase).
Further passage of the stabilized current through the system causes dissolution of the
conduction channel of the Yanson point contact (decommutation phase). The dissolution phase is initiated by the gapless electrode system formed on the surface of the
conduction channel upon the formation of the point contact. The process acquires
a cyclic character with alternating phases of formation and dissolution of dendritic
point contacts, which can be seen in Fig. 1a in the form of cyclic variations in the
electric resistance of the system under study. This is the cyclic switchover effect [3].
The transformations of the Yanson point-contact nanostructure are shaped by the
quantum shell effect [7] and characterized by the existence of metastable quantum
states corresponding to certain diameters of conduction channel, which can be registered as steps (Fig. 1b) in the dependence electric resistance R versus time t [3]. A
set of the metastable quantum states the system can be in during its evolution is a
unique characteristic of the system. Its registration in the form of a histogram of the
conductance of dendrite point contacts allows using it as an efficient tool for selective
detection in gaseous and liquid media [4]. Thus, the conductance histogram of point
contacts formed in the analyzed medium is the output characteristics of the selective quantum sensors based on the cyclic switchover effect [3, 4]. The conductance
histogram characterizes the probability of formation of the metastable quantum states
of the system during its evolution. The distribution of the probabilities of formation
of point contacts with certain values of the conduction channel conductance is in
direct correlation with the parameters of the medium in which the point-contact
structures are formed and destroyed. To get some quantitative data in the process of
detection, it is necessary to distinguish the differential response caused by the action
of the analyte on the sensing element. The output basic characteristic obtained in a
“pure” medium with virtually no agents influencing the sensing element or analyzed
substances can be used as the background signal. That is why it is crucial to know the
fundamental features of the processes that contribute to the formation of the background characteristics—in our case, of the conductance histogram of point-contact
structures commutating the interelectrode space in the cyclic switchover effect.
An important source of information needed for obtaining a conductance histogram
is the phase of the anode destruction of a Yanson point contact from the moment it is
created to the complete interruption of direct conductance (decommutation phase).
A key role in this process belongs to the gapless electrode system formed on the
surface of the conduction channel of a point contact at the moment of its creation.
Information about the nature of the GES operation can be gained by analyzing the
lifetimes of Yanson point contacts during the evolution of the nanostructure from its
A. P. Pospelov et al.
large diameters of the conduction channel, while high resistances are those of the
contacts with small diameters, down to the size of an atom [3]. The steps in the curve
R(t) (Fig. 1b) reflect the existence of metastable quantum energy states of contacts
with certain diameters [10], which emerge in the process of the contacts’ evolution.
The process of the cyclic switchover effect can be thought of as follows. As the
current starts flowing through the needle tip, a dendrite starts growing along the
lines of force of the electric field toward the “anvil” (precommutation phase) [3].
Sometime later the dendrite tip reaches the surface of the counterelectrode. In the
point of contact, a dendritic Yanson point contact is formed (commutation phase).
Further passage of the stabilized current through the system causes dissolution of the
conduction channel of the Yanson point contact (decommutation phase). The dissolution phase is initiated by the gapless electrode system formed on the surface of the
conduction channel upon the formation of the point contact. The process acquires
a cyclic character with alternating phases of formation and dissolution of dendritic
point contacts, which can be seen in Fig. 1a in the form of cyclic variations in the
electric resistance of the system under study. This is the cyclic switchover effect [3].
The transformations of the Yanson point-contact nanostructure are shaped by the
quantum shell effect [7] and characterized by the existence of metastable quantum
states corresponding to certain diameters of conduction channel, which can be registered as steps (Fig. 1b) in the dependence electric resistance R versus time t [3]. A
set of the metastable quantum states the system can be in during its evolution is a
unique characteristic of the system. Its registration in the form of a histogram of the
conductance of dendrite point contacts allows using it as an efficient tool for selective
detection in gaseous and liquid media [4]. Thus, the conductance histogram of point
contacts formed in the analyzed medium is the output characteristics of the selective quantum sensors based on the cyclic switchover effect [3, 4]. The conductance
histogram characterizes the probability of formation of the metastable quantum states
of the system during its evolution. The distribution of the probabilities of formation
of point contacts with certain values of the conduction channel conductance is in
direct correlation with the parameters of the medium in which the point-contact
structures are formed and destroyed. To get some quantitative data in the process of
detection, it is necessary to distinguish the differential response caused by the action
of the analyte on the sensing element. The output basic characteristic obtained in a
“pure” medium with virtually no agents influencing the sensing element or analyzed
substances can be used as the background signal. That is why it is crucial to know the
fundamental features of the processes that contribute to the formation of the background characteristics—in our case, of the conductance histogram of point-contact
structures commutating the interelectrode space in the cyclic switchover effect.
An important source of information needed for obtaining a conductance histogram
is the phase of the anode destruction of a Yanson point contact from the moment it is
created to the complete interruption of direct conductance (decommutation phase).
A key role in this process belongs to the gapless electrode system formed on the
surface of the conduction channel of a point contact at the moment of its creation.
Information about the nature of the GES operation can be gained by analyzing the
lifetimes of Yanson point contacts during the evolution of the nanostructure from its