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1.
It was found that the use of multifiber probes and photon traps allows contactless measurement of Raman scattering spectra for small amounts (~1 µg) of organic and inorganic compounds at exposures of 1–16 s. The possibility of improving the sensitivity of Raman scattering spectrum measurement using globular photonic crystals as matrices or substrates carrying analyzed compounds was studied. 相似文献
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I.F. Ginzburg G.L. Kotkin 《The European Physical Journal C - Particles and Fields》2000,13(2):295-300
The luminosity distribution in the effective mass at a photon collider usually has two peaks which are well separated: a high energy peak with mean energy spread about
5–7% and a wide low energy peak. The low energy peak strongly depends on the details of the design and is unsuitable for the
study of new physics phenomena. We find a simple approximate form for the spectra of colliding photons for and colliders, whose convolution describes the high energy luminosity peak with a good accuracy in most of the essential preferable
region of the parameters.
Received: 14 September 1999 / Published online: 17 February 2000 相似文献
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A new type of resonator cells (photon traps) has been worked out, which ensures the Raman opalescence regime (i.e., the conditions under which the relative Raman scattering intensity at the outlet of the cells increases significantly as compared to the exciting line intensity. The Raman scattering spectra of a number of organic and inorganic compounds placed in photon traps are studied under pulse-periodic excitation by a copper-vapor laser. 相似文献
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Photoluminescence excitation spectra of donor-acceptor pairs have been observed in phosphorus doped ZnTe. Binding energies of the donor and the acceptor is estimated from the spectra. Emission spectra measured under below-band-gap excitation showed sharp bands superimposed with a broad emission band. The result indicates the existence of two decay processes under the below-band-gap excitation: (1) recombination of an electron and a hole trapped on a given D-A pair, and (2) recombination of D-A pairs with various distances for which bound electrons are formed via conduction band. 相似文献
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With no restrictions on the value of optical density, we derive an equation that describes the photoluminescence excitation spectra of separate components with overlapping absorption bands in a multicomponent medium. Based on the equation obtained, we propose methods for measuring the ratios of absorption optical densities of the components and quantum yields of their luminescence. The applicability of the proposed methods is demonstrated by measuring the characteristics of coumarin and porphyrin dissolved in different proportions in ethanol. We have also measured the quantum yield and luminescence decay time of the radiationinduced color centers F 3 + in the lithium fluoride crystal and calculated probabilities of radiative and nonradiative transitions from the first excited singlet state of these centers. 相似文献
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Yu. P. Voinov V. S. Gorelik A. Yu. Pyatyshev M. F. Umarov 《Bulletin of the Lebedev Physics Institute》2012,39(12):341-346
The photoluminescence spectra of aromatic compounds in a photon trap under ultraviolet pulse-periodic excitation are recorded. It is shown that the photoluminescence spectrum shape depends on the material layer thickness in a cell, physical state of the sample, and exciting radiation characteristics: as the layer thicknesses decreases, the intensity is significantly redistributed, which is explained by the transition from spontaneous luminescence to superluminescence. 相似文献
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I. Kh. Akopyan M. E. Labzovskaya A. A. Lisachenko B. V. Novikov A. Yu. Serov V. V. Titov N. G. Filosofov 《Physics of the Solid State》2016,58(9):1767-1771
The influence of oxygen desorption on the photoluminescence of zinc oxide has been investigated. Photodesorption and thermal desorption of oxygen have been controlled using mass spectrometry. It has been found that the removal of oxygen from the ZnO surface leads to a manifold increase in the exciton photoluminescence intensity. The process has a reversible character. The mechanism of increase in the exciton luminescence intensity of ZnO during the oxygen desorption has been discussed. 相似文献
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The low temperature optical spectra of free base porphin in crystalline anthracene have been observed in the visible region of the spectrum. Quasilines and broad components were observed in the region of the forbidden Q bands. Site selection techniques were used to separate the spectra of inequivalent site species, and vibronic frequencies were assigned in the ground state and excited Q states. The relative strengths of the broad and quasiline components of the spectra in the Qx and Qy states indicated that the host lattice may affect the relative transition strengths of Qx and Qy. These results indicated that the strength of the transition to Qx is greater than that of Qy for a free porphin molecule. 相似文献
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Optical data are presented for a novel thin film structure based on anthracene. Thin films of the 9-butyl–10-anthryl propionic acid derivative were prepared using the Langmuir-Blodgett technique. By applying electric fields in excess of 106 V cm?1 both electroabsorption and electroluminescence results have been obtained. The electroluminescence spectrum exhibits a shoulder at the wavelength where the maximum in the fluorescence spectrum occurs. 相似文献
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Optical spectra of highly excited quantum wires at low temperatures have been studied within the dynamical screening approximation. We found a strong Fermi-edge singularity (FES) in the photoluminescence spectra. The spectral shape and FES intensity strongly depend on temperature in agreement with recent experimental results. 相似文献
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Enhancing redshift phenomenon in time-resolved photoluminescence spectra of AlGaN epilayer 下载免费PDF全文
AlGaN epitaxial layer has been studied by means of temperature-dependent time-integrated photoluminescence(PL)and time-resolved photoluminescence(TRPL). An enhancing redshift phenomenon in TRPL spectra with increasing temperature was observed, and the localized excitons behaved like quasi two-dimensional excitons between 6 K and 90 K. We demonstrated that these behaviors are caused by a change in the carrier dynamics with increasing temperature due to the competition of carriers' localization and delocalization in the AlGaN alloy. 相似文献
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Conclusions The studies performed here have shown that the superlattice samples studied exhibit photoluminescence spectra which agree
with the Kronig-Penney model, although in calculating the energies of the radiative transitions it is necessary to take into
account the binding energy of the excitons,E
B. Due to the exciton—phonon interaction, the 1HH peak breaks up on the long wavelength side into a Poisson distribution. The
energy of the LO phonon so determined is 34 meV. Bands due toD
0-A
0 andD
0X transitions, caused by remaining low-level impurities in the GaAs crystals are also observed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 61, Nos. 3–4, pp. 241–245, September–October, 1994. 相似文献
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Fabrication and temperature-dependent photoluminescence spectra of Zn–Cu–In–S quaternary nanocrystals 下载免费PDF全文
A series of Zn-Cu-In-S nanocrystals (ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photoluminescence (PL) spectra of the ZCIS NCs show a redshift with decreasing intensity at low temperature (50-280 K) and a blueshift at high temperature (318--403 K). The blueshift can be explained by the thermally active phonon-assisted tunneling from the excited states of the low-energy emission band to the excited states of the high-energy emission band. 相似文献