Učinak ozračivanja elektronima visoke energije na optička svojstva olovnog stakla

Optical absorption and photoluminescence spectra of lead silicate glass irradiated by 5- to 10-MeV electrons are studied. High-energy electron irradiation is shown to result in the formation of colour centres generally similar to those being formed by X-ray and γ-radiation. The most probable factors responsible for the non-sensitivity of the photoluminescence of the investigated lead silicate glass to the electron irradiation are discussed.U vidljivom smo području proučavali apsorpciju i fotoluminescentne spektre olovnog stakla ozračenog elektronima energije 5 do 10 MeV. Pokazuje se da to ozračivanje stvara centre boje vrlo slične onima koji se postižu ozračivanjem Xi γ-zračenjem. Raspravljamo o najvjerojatnijim uzrocima neosjetljivosti fotoluminescencije na ozračivanje elektronima

Resonant Raman studies of compositional and size dispersion of CdS₁₋ₓSeₓ nanocrystals in a glass matrix

Resonant Raman scattering spectra of glass-embedded CdS₁₋ₓSeₓ nanocrystals are measured and complemented with TEM and optical absorption as well as photoluminescence data. The selectivity of the resonant Raman process not only for the size, but also for the composition of nanocrystals within the ensemble, is directly observed in the dependence of phonon band frequency, linewidth and shape on the excitation wavelength

Nanostructured Silver Substrates With Stable and Universal SERS Properties: Application to Organic Molecules and Semiconductor Nanoparticles

Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60–80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time

Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange

Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC) surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO) phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs

Низькотемпературна люмінесценція суперіонних кристалів Cu6PS5Br

Photoluininescence (PL)  spectra of Cu6PS5Br crystals are studied in a broad spectral range (0.5-2 µm) at 77 K, under various excitation conditions. In the PL spectra a number of bands of different origin is revealed. The computer processing of the spectrum is carried out and the mechanisms of the radiative recombination resulting in the band appearance, are discussed. The comparative analysis of the PL and optical absorption spectra is performed.Исследованы спектры фотолюминесценции кристаллов Cu6PS5Br в широком спектральном диапазоне (0.5 - 2 мкм) при температуре 77 К и различных условиях возбуждения. Обсуждаются механизмы излучательной рекомбинации, приводящие к возникновению полос различной природы, обнаруженных в спектрах фото-люминесценции. Проведен сравнительный анализ спектров фотолюминесценции и оптического поглощения.Досліджені спектри фотолюмінесценції кристалів Cu6PS5Br в широкому спектральному діапазоні (0.5 - 2 мкм) при температурі 77 К та різних умовах збудження. Обговорюються механізми випромінювальної рекомбінації, що приводять до виникнення смуг різної природи, виявлених у спектрах фото-люмінесценції. Проведено порівняльний аналіз спектрів фотолюмінесценції та оптичного поглинання.

Resonant Raman studies of compositional and size dispersion of CdS₁₋ₓSeₓ nanocrystals in a glass matrix

Resonant Raman scattering spectra of glass-embedded CdS₁₋ₓSeₓ nanocrystals are measured and complemented with TEM and optical absorption as well as photoluminescence data. The selectivity of the resonant Raman process not only for the size, but also for the composition of nanocrystals within the ensemble, is directly observed in the dependence of phonon band frequency, linewidth and shape on the excitation wavelength