A study is performed of the conditions needed to generate an incoherent exciton echo in a layer of CdSe/CdS/ZnS semiconductor quantum dots.

A theoretical investigation is performed of the possibility and conditions of locked exciton echo excitation and modulation spectroscopy on the localized excitons of an ensemble of nanocrystals with an emitting core of CdSe.

A theoretical investigation is performed for the possibility and conditions of the stimulated induction of excitons in a thin layer of semiconductor quantum dots upon excitation by continuous-wave laser radiation.

The possibility and conditions of recording and reading out two-quantum transient holograms on the exciton levels of CdSe/CdS/ZnS-type semiconductor quantum dots are studied theoretically.

The effect of green and ultraviolet laser light on Ba_0.8Sr_0.2TiO_3/LaMnO_3 heterostructure electrical resistance was studied. In 80-200 K range illumination induces transient resistance component at 15 transient component is 12 s. The negative photoresistance effect is found under green, infrared and ultraviolet illumination.

We have synthesized luminescent YVO4: Yb, Er nanoparticles (NPs) in the size range of 10–700 nm. A bright green luminescence of the dry NPs powder due to Er3+ ions emission centered at 526 and 550 nm was compared for upconverting and downconverting laser excitations at 980 nm and 257 nm, respectively. Moreover, the NPs exhibited bright luminescence in colloidal water solution upon 980 nm laser irradiation. All experiments showed very weak radiative 4F9/2→4I15/2 emission from Er3+ ions at 660 nm that indirectly indicates low efficiency of multiphonon intraionic transitions and insensitivity of the NPs to the luminescence quenchers in the water solution. A broad red band in the luminescence spectrum appearing under intense 257 nm laser excitation can be attributed to emission from crystal lattice defects in the NPs. Based on these facts we propose that YVO4: Yb, Er NPs are promising as efficient upconversion fluorescent nanoprobes for certain biological applications, like optogenetics.

We studied the dynamics of photoinduced charge carriers in core/shell CdSe/CdS quantum dots (QDs) of two sizes, 2.0 and 2.9 nm, in a toluene colloid by femtosecond up-conversion spectroscopy. We observed the luminescence kinetics of QDs excited by 50 fs laser pulses at a wavelength of 385 nm. The modeling of experimental data showed that a 0.5 ps rise of the luminescence intensity corresponds to the process of electron thermalization. The two-exponential luminescence decay with characteristic times in the picosecond range corresponds to populating of two types of traps, which we associate with core and shell defects. Electron- hole recombination process does not affect the shape of the luminescence kinetics in the picosecond range. A comparative analysis indicates that the concentration of defects in 2.0nm QDs is greater than that in 2.9nm QDs, while potential wells, which charge carriers eventually escape due to thermal activation, are deeper for 2.9 run QDs.

We have studied picosecond dynamics of photo-induced charge carriers in CdSe/CdS nanoparticles with sizes of 2.0 and 2.9 nm in toluene colloidal solutions using femtosecond up-conversion spectroscopy. The kinetics of nanoparticles luminescence excited by laser pulses of 50 fs duration at 350 nm were observed. The simulation of experimental data showed that electron thermalization occurs within 0.5 ps, while recombination processes have characteristic times of 5 and 20 ns, although these cannot be unequivocally identified using the simplest recombination model with direct transitions and single type of traps. However, a comparative analysis indicates a fundamental difference in the mechanisms responsible for the dynamics of charge carriers in the time interval up to 5 ps after laser excitation, which we associate with different structures of traps in 2.0 and 2.9 nm particles.

The effect of an incoherent photon echo is studied experimentally and theoretically in (LiYFEr3+)-Li-7 crystal ( transition). This is considered as a promising material for Raman optical quantum memory due to the extremely narrow optical transitions. Oscillations of the photon echo intensity versus the external static magnetic field are observed. The theory shows that the oscillation period is very sensitive to one of the parameters of the spin Hamiltonian in the excited state, thereby making the incoherent photon echo convenient for spectroscopic measurements.

We have studied theoretically a possibility to construct a quantum gate on the basis of semiconductor quantum dots of a core/shell type.

The Stark coefficient of the Er 3+ ion in Y 2 SiO 5 is determined for transition). The stark photon echo beating method (SPEB) was used: the pseudo-Stark frequency shift was measured from the period of beats of the temporal form of the photon echo signal. Light beatings were caused by the use of a weak electric field pulse that splits the frequencies of optical transitions of nonequivalent subgroups of echo-active Er 3+ ions in Y 2 SiO5