Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Investigation of free and bound excitons in strained ZnTe films grown by MBE on GaAs(100) substrates (2000)
    Springer
    Physics of the solid state 42 (2000), S. 236-240 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is reported of the reflectance and low-temperature photoluminescence (PL) spectra of ZnTe films grown by molecular-beam epitaxy (MBE) on GaAs substrates [(100) orientation, 3° deflection toward 〈110〉]. It is shown that the strain-induced splitting of the free-exciton energy level (ΔE ex) does not depend on ZnTe film thickness within the 1–5.7 µm range and is due to biaxial in-plane film tension. The stresses are primarily determined by the difference between the thermal expansion coefficients of the film and the substrate. It is also shown that the residual stresses originating from incomplete relaxation of the film lattice parameter to its equilibrium value at the growth temperature likewise provide a certain contribution. The position of the spectral line of an exciton bound to a neutral acceptor (As) is well approximated in terms of the present models, taking into account the stresses calculated using the value of ΔE ex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1131152
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Specific features in the temperature dependence of photoluminescence from CdTe/ZnTe size-quantized islands and ultrathin quantum wells (1999)
    Springer
    Physics of the solid state 41 (1999), S. 647-653 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study has been carried out of the temperature dependences of luminescence spectra on a large number of CdTe/ZnTe structures differing in average thickness, 〈L z〉=0.25–4 monolayers (ML), and CdTe layer geometry (continuous, island type). The influence of geometric features in the structure of ultrathin layers on linewidth, the extent of lateral localization of excitons, their binding energy, and exciton-phonon coupling is discussed. It is shown that in island structures there is practically no lateral exciton migration. The exciton-phonon coupling constant in a submonolayer structure has been determined, Γph=53 meV, and it is shown that in structures with larger average thicknesses Γph is considerably smaller. Substantial lateral exciton migration was observed to occur in a quantum well with 〈L z〉=4 ML, and interaction with acoustic phonons was found to play a noticeable part in transport processes. It has been established that the depth of the exciton level in a quantum well and structural features of an ultrathin layer significantly affect the temperature dependences of integrated photoluminescence intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130842
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Deep-level optical spectroscopy of ZnTe (1998)
    Springer
    Physics of the solid state 40 (1998), S. 924-929 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The variation of the deep-level spectrum of stoichiometric ZnTe in the various stages of its purification and annealing in saturated Zn vapor has been studied by low-temperature photoluminescence and IR Fourier spectroscopy. The relation between the concentration of the main residual impurities with complex formation probability is analyzed. We have succeeded in observing for the first time Z center emission in ZnTe, as previously in CdTe and ZnSe. This center is shown to be a multicharged impurity in ZnTe. The activation energies of these levels have been determined. A comparison of the data obtained by chemical analysis with optical spectra has led to a conclusion that this center is associated with isolated oxygen present on the metalloid sublattice. While this emission exhibits the same specific features in a number of II–VI compounds (a high recombination rate, narrow emission lines, extremely weak electron-phonon coupling), the positions of the levels in the band gap and the characteristic charge state distinguish ZnTe from CdTe and ZnSe. As a rule, the Z center forms in a material in decomposition of various complexes (for instance, of the complex responsible for the 1.65-eV emission in ZnTe) and disappears when the material is doped leading to formation of the same complexes. An assumption is put forward that this center creates the main compensating deep levels and is an essential component of easily forming complexes with impurities. Its position in the lower half of the ZnTe band gap (in contrast to ZnSe and CdTe) makes preparation of the n material difficult.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130449
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Magnetic Models of Pulsars and Rotating Neutron Stars (1969)
    [s.l.] : Nature Publishing Group
    Nature 222 (1969), S. 230-231 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The authors describe how magnetic models of pulsars can account for the narrowness of the beam of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/222230a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    A dynamic theory of type III solar radio bursts (1972)
    Springer
    Solar physics 24 (1972), S. 444-456 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Numerous experimental data indicate that type III solar radio bursts are generated by the streams of fast electrons in the corona. The process of the electron acceleration in the flare region is, in general, of the character of a short time local explosion. As a result, a spatially limited stream with inhomogeneous front and back is formed in the corona. The present paper shows that such a spatial structure of fast electrons radically changes the dynamics of the stream instability development. In particular, for example, despite strong quasilinear relaxation, in this case the electron stream can generate plasma waves in the corona for a long time due to faster electrons escaping out of the front of the stream. The extension of the stream in the outer corona where the collisions are negligible is of similar character. The maximum of the energy density in the packet of excited plasma waves travels in the corona with constant mean velocity which is defined by the fast-electron energy at the moment of their formation in the flare region. Therefore, in spite of the considerable influence of quasilinear effects on the stream motion, the velocity of type III sources found in terms of the drift velocity remains unchanged. This creates the illusion of stream stabilization. The energy dissipation of plasma waves for the low frequency type III bursts is fully determined by Landau damping in the tail of the stream. Because of this, the temperature estimates of the outer corona from time profiles of type III bursts are incorrect. The theoretical curves of the time variation of radiation at different frequencies agree well with the experimental data in the hectometer wave range under the assumption that the electromagnetic wave generation takes place at the second harmonic of the plasma frequency. In this case it is necessary to decrease the electron density in the solar corona at distances of about 5 to 30 R ⊙ 4 times as compared with the previous densities previously derived from type III data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00153387
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Positions of solar storm burst sources by observations with a heliograph based on the UTR-2 antenna at 25 MHz (1980)
    Springer
    Solar physics 66 (1980), S. 393-409 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract To locate two-dimensional positions of the solar decametric radio bursts a heliograph was developed on the basis of the UTR-2 radiotelescope (Khar'kov) operated in the range 10–26 MHz. The beamwidth of the heliograph rapid-scanning pencil-beam is 25 arc min at 25 MHz, and its field of view is about 3.5° (E-W) × 2.0° (N-S). The instrument yields rapidly forty records of the radio brightness of all (8 × 5) elementary parts (each 25 arc min in diameter) of the investigated sky area during every period of 1/4 s. Both coordinates of a burst center are measured with an accuracy 5 arc min. The bandwidth of the receiving system is 10 kHz. The heliograph operates in conjunction with a radiospectrograph connected to the output of a N-S arm of the UTR-2 array. The data observations with the UTR-2 correspond only to one linear polarized component. The ionospheric distortion of the test records of the radio source Cassiopeia-A that occurred sometimes is illustrated. First results of 25 MHz observations of the solar radio storm in August, 1976 with the heliograph are presented here. This storm is accompanied by the compact sunspot group travelling all over the optical disk. The type III and stria bursts were predominant during the storm. On the given day the scattering regions of their apparent centers were overlapped and the sizes of these regions were usually not more than 5 arc min. On some days there occurred additional burst sources displaced in position from the persistent storm region. It was found out that, as a rule, 25 MHz stria-bursts from the type IIIb chain coincided in position with the following type III burst at the same frequency. The difference of the daily averaged coordinates of both stria and type III bursts was considerably smaller than the mean diameter of their sources. The radial distance of the 25 MHz storm region from the solar center was calculated by using the three methods. The storm height was estimated as 1.8R ⊙ from the rotation rate close to the central meridian of the storm center. Definite association of the spots with the storm near the limb allowed to determine the average value 2.1R ⊙ for the height. The limb measurements give the mean height of 2.3R ⊙. The center-to-limb variation of the storm source height is a known fact in the meter-wavelength range. This is the evidence of the propagation effects in the solar corona being essential to interpret the results of the radio source location.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00150593
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Frequency and time splitting of decameter solar radio bursts (1974)
    Springer
    Solar physics 39 (1974), S. 223-231 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper deals with the observations of the fine structure of type III bursts in the 12.5–25 MHz band using the UTR-2 (IRE AN UkSSR, Kharkov) radio telescope. A fine structure arises in the form of chains of short-lived narrow-band bursts. The chains have a frequency drift analogous to type III bursts. Observations allow two different-type chains to be singled out. Ordinary stria-bursts, split-pairs and triplets belong to the first type chains. They may also involve the echo-type phenomena The second type chains (IIId) involve diffusive stria-bursts, diffusive split-pairs and triplets. The analysis of a harmonic structure of chains incidates that the first type chains are generated at the frequencies close to the local plasma electron frequency ω pe . The second type chains and, consequently, diffusive stria-bursts correspond to the second harmonic of the plasma frequency 2ω pe . Experimental data evidence that the type III bursts with a fine structure are excited by the faster particle streams than the ordinary type III bursts with a diffusive character both of the fundamental and the second harmonic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154983
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Frequency and time splitting of decameter solar radio bursts (1974)
    Springer
    Solar physics 39 (1974), S. 213-222 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper deals with the stria-burst observations by the UTR-2 radio telescope (IRE AN UkSSR, Kharkov) at the frequencies of 12.5–25 MHz. Two varieties of these bursts are pointed out: ordinary stria-bursts and diffusive stria-bursts. The ordinary stria-bursts may occur isolated, as split-pairs and splitted triple bursts (triplets). At the frequency 25 MHz, the ordinary stria-bursts are characterized by the average duration about 1 s, the band width 0.07 MHz and the frequency drift 0.07 MHz s−1. A scale of the frequency splitting in pairs and triplets is 0.1 MHz. The diffusive stria-bursts have essentially larger duration (of the order of 10 s) and no visible frequency drift. Like the ordinary stria-bursts, the diffusive ones may appear isolated and in the form of split-pairs and triplets. The occurrence of echoes is typical of both types of stria-bursts which are a succession of two or several (multiple echoes) similar bursts separated by the time interval 1.5–2.5 s for the ordinary and by 3–10 s for the diffusive stria-bursts. Sometimes the bursts with two scales of the frequency splitting are observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154982
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The plasma radiation of flare kernels (1983)
    Springer
    Solar physics 88 (1983), S. 297-313 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We offer a coherent plasma-emission mechanism for intense microwave radiation of a flare in the impulsive phase. The radiation arises because of a loss-cone instability of plasma waves near the upper hybrid frequency in the energy release region (flare kernel). Under typical conditions of a flare kernel, conversion of plasma waves into electromagnetic ones causes the radio emission to dominate the second harmonic of the plasma frequency. The radiation is polarized in the extraordinary sense. The Bernstein mode loss-cone instability leads to a zebra-pattern in the microwave radiation. MHD-oscillations of the flare kernel give rise to pulsations of the microwave and hard X-ray emission. The plasma mechanism offers new possibilities of flare plasma diagnostics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196194
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The energy supply systems in the heart valve leaflet cells during kryopreservation and storage (1998)
    Springer
    Bulletin of experimental biology and medicine 125 (1998), S. 558-560 
    Details
    ISSN: 1573-8221
    Keywords: cardiac valve allografts ; kryopreservation ; energy supply systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The condition of animal heart valve allografts after kryopreservation and storage is assessed. After 2-day storage of preparations at 4°C tissue ATP content decreases by 1.5–2 times and remains at this level for 5 days. Freezing of tissues without kryoprotector results in more than 10-fold drop in ATP content and a 2-fold decrease in the total content of pyridine nucleotides. After kryopreservation these parameters decrease by 1.2–1.4 times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445239
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...