A detailed interpretation of exciton lines caused by the presence of a lithium impurity in ZnO crystals (T = 4.2 K) was carried out. The 368.5-nm line is caused by radiative recombination of excitons bound on neutral donor states LiixThe 371.2-nm line is caused by the same process but occurring simultaneously with the transition of the donor to the excited state. The 368.2-nm line occurs when excitons bound on ionized Lii+states emit. The 369.7-nm line is the emission of excitons bound on acceptor complexes of the form (Zni+LiZn divide (Lii+LiZn divide etc. The measurements also made it possible to calculate the ionization energy of shallow donors Liix as E-d = 0.033 eV. Thus, a method for exciton spectroscopy of lithium states affecting the optical and electrophysical characteristics of zinc oxide has been developed.

The principal results of the investigation of thermally stimulated electron–hole and ionic processes in hydrothermal and gas-phase ZnO single crystals preexcited at low temperatures, based on simultaneous study of photo-EPR and thermoluminescence (TL), are presented. The nature of the traps determining the TL peaks at 17, 24, 40, 53, 90–110, 140–150, and 160–200 K is discussed. In particular, it has been established that the lithium paramagnetic centers (Li Zn + –O I ) play the role of hole traps in ZnO giving green and red TL in the temperature range 160–200 K and, in the case of association with small-sized donors, also TL in the temperature range 90–110 K. The other traps are electronic in character, and in the presence of acceptor lithium in the crystals, they form yellow-orange TL. Optical quenching of TL has been evaluated, and it has been found that there is a difference Δ E ≈ 0.75 eV between the thermal and optical energies of ionization of lithium acceptors. Irreversible ionic processes associated with the “healing” of cationic vacancies at T ≈ 360–420 K have been revealed.

It is shown that changes in luminescence characteristics of zinc sulfide and oxide in the presence of external effects that alter the surface charge are associated with a change in the parameters of surface barriers and can be explained within the framework of a model that takes into account separation of recombining partners in the Schottky barriers. We suggest a barrier mechanism for the effect of the surface region of a crystal on experimentally measured luminescence parameters and show that errors occuring in the measurement of these parameters can reach 10% and greater, depending on the depth of penetration of light.

The streamer chamber of a magnetic GIBS spectrometer made froin a 2-meter SKM-200 chamber is described. The chamber design and its construction are discussed. Focusing on the problems of installing the chamber into the interpolar gap of an electromagnet and its connection to a high-voltage pulse generator. The chamber is used in beams of accelerated nuclei from the synchrophasotron at the Joint Institute for Nuclear Research.

Controlled photomultipliers may be used for analysing modulation frequencies and other time parameters of radiation, which lie beyond the bandwidth or the time parameters of secondary emission systems. On the basis of the electron-optical characteristics of a control system for photomultipliers with two control grids, the properties to be expected are investigated for quasi-stationary operation an...