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1.
AMBIKA NEGI R V HARIWAL ANJU SEMWAL R G SONKAWEDE D KANJILAL J M S RANA R C RAMOLA 《Pramana》2011,77(4):707-714
In the present study, the effects of swift heavy ion beam irradiation on the structural, chemical and optical properties of
Makrofol solid-state nuclear track detector (SSNTD) were investigated. Makrofol-KG films of 40 μm thickness were irradiated with oxygen beam (O8 + ) with fluences ranging between 1010 ion/cm2 and 1012 ion/cm2. Structural, chemical and optical properties were investigated using X-ray diffraction, FTIR spectroscopy and UV–visible
spectroscopy methods. It is observed that the direct and indirect band gaps of Makrofol-KG decrease after the irradiation.
The XRD study shows that the crystalline size in the films decreases at higher fluences. The intensity plots of FTIR measurements
indicate the degradation of Makrofol at higher fluences. Roughness of the surface increases at higher fluence. 相似文献
2.
Numerical modeling of dynamical processes in semiconductor lasers with external delayed optical feedback has been performed
on the basis of the rate equations taking into account the quantum fluctuations of radiative transition rates. It has been
shown that the nature of the optoelectronic signal as a function of pump current is determined by the magnitude of the optoelectronic
coupling and corresponds to the behavior of the autocorrelation function of the radiation. It has been found that the radiation
coherence decreases substantially with strong optical feedback. Experimental measurements confirming the theoretical results
have been performed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 809–813, November–December, 2008. 相似文献
3.
N. G. Semaltianos W. Perrie P. French M. Sharp G. Dearden S. Logothetidis K. G. Watkins 《Applied Physics A: Materials Science & Processing》2009,94(4):999-1009
Femtosecond laser (180 fs, 775 nm, 1 kHz) ablation characteristics of the nickel-based superalloy C263 are investigated. The
single pulse ablation threshold is measured to be 0.26±0.03 J/cm2 and the incubation parameter ξ=0.72±0.03 by also measuring the dependence of ablation threshold on the number of laser pulses.
The ablation rate exhibits two logarithmic dependencies on fluence corresponding to ablation determined by the optical penetration
depth at fluences below ∼5 J/cm2 (for single pulse) and by the electron thermal diffusion length above that fluence. The central surface morphology of ablated
craters (dimples) with laser fluence and number of laser pulses shows the development of several kinds of periodic structures
(ripples) with different periodicities as well as the formation of resolidified material and holes at the centre of the ablated
crater at high fluences. The debris produced during ablation consists of crystalline C263 oxidized nanoparticles with diameters
of ∼2–20 nm (for F=9.6 J/cm2). The mechanisms involved in femtosecond laser microprocessing of the superalloy C263 as well as in the synthesis of C263
nanoparticles are elucidated and discussed in terms of the properties of the material. 相似文献
4.
S. Dinakaran Sunil Verma S. Jerome Das G. Bhagavannarayana S. Kar K. S. Bartwal 《Applied Physics A: Materials Science & Processing》2010,99(2):445-450
Potassium dihydrogen phosphate (KDP) crystals grown along the type-II phase-matching direction were investigated for crystalline
and optical perfection. High-resolution X-ray diffraction (HRXRD) technique was used for investigating crystalline perfection.
UV–VIS transmission, Mach–Zehnder interferometry, birefringence interferometry and conoscopy were performed for optical characterization.
HRXRD results show that the grown crystals have good structural perfection. A uniform transmittance of 92% was observed in
the visible region of the spectrum. Straight and parallel fringes were observed in Mach–Zehnder interferometric studies. A
symmetrical fringe pattern was obtained in conoscopy images. These interferometric results suggest that the optical homogeneity
of the grown crystal was good and not influenced by the growth technique. 相似文献
5.
The ablation behavior of single crystalline sapphire with nanosecond laser pulses at 157 nm wavelength is investigated. Ablation
rates of about 10 to 100 nm/pulse are obtained at fluences ranging from 1 to 9 J/cm2. At moderate fluences, incubation behavior is observed, i.e. ablation starts after material modification by a number of laser
pulses. The ablation can be utilized to fabricate sapphire micro-optics. The capability of creating lenses or gratings on
the tip of sapphire fibers is demonstrated. Multilevel diffractive optical elements and high resolution gratings with 1 μm
period are fabricated on planar sapphire substrates. 相似文献
6.
I. Kh. Abdukadyrova 《Journal of Applied Spectroscopy》2007,74(2):278-282
Features of the thermoradiative changes in the optical absorption and luminescence spectra of leucosapphire (colorless sapphire)
crystals irradiated by neutron fluences within the range 5·1015 to 5·1019 cm−2 have been studied in the visible region. The stepwise character of these processes was established as well as the basic steps
involved in bleaching the induced color of the wafers as a result of isochronal annealing. Some anomalies have been observed
in the temperature dependence of the optical density of the 460–620 nm bands, the activation energies for the color centers
as well as the color center concentrations have been calculated, and the nature of the radiation-induced centers has been
analyzed. An analytical expression is proposed to describe the accumulation kinetics for the centers during irradiation of
the crystals by reactor neutrons. It is concluded that there is an interconnection between, for example, the 460 nm color
centers and the 540 nm luminescence centers, and that there is a common mechanism for the process of radiation-induced defect
formation, initially responsible for their formation in the crystal. The possible effect of reabsorption of radiation on the
behavior of the Y(Φ) curve in the irradiated material is discussed.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 247–251, March–April, 2007. 相似文献
7.
Q.X. Zhao P. Klason M. Willander 《Applied Physics A: Materials Science & Processing》2007,87(1):27-30
Zinc oxide nanorods have been grown by vapor–liquid–solid (VLS) catalytic growth. The optical properties and structures properties
of the grown ZnO nanostructures have been studied by photoluminescence, high resolution X-ray diffraction and scanning electron
microscopy. The results show that the formation of ZnO nanostructures is strongly influenced by the growth conditions and
used substrates. It was found that oriented ZnO nanorods are grown more easily on a substrate with a similar crystalline structure
as ZnO. By optimizing growth conditions, oriented-ZnO nanorods grown on Si(001) substrate with a diameter of around 300 nm
and lengths of 20 to 35 μm have been achieved, and they show excellent optical properties. Laser action has been observed
at room temperature by using optical pumping.
PACS 81.05.Dz; 81.10.Bk; 81.16.Hc 相似文献
8.
Results from studies of the effect of the action of optical radiation on the characteristics of light-emitting diodes (LEDs)
produced using the binary heterostructure GaxAl1−xAs (λ=0.88 μm) are presented. High sensitivity of the LED to the following parameters of the optical radiation is shown: flux
density, quantum energy, and exposure dose. The action of optical radiation in the form of a band with a maximum at 255 nm
on the LED heterostructures lowers the leakage current into the bulk, decreases the loss identified as surface leakage current
by about an order of magnitude, increases the radiated power by 50–100% in the current region up to 10−3 A, and increases the overall light output of the diodes.
Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 109–114, August,
1997. 相似文献
9.
V. V. Gruzinskii S. M. Kazakov M. N. Kaputerko I. I. Kulak V. A. Suchkov 《Journal of Applied Spectroscopy》1998,65(2):224-231
Information on paths in absorption and deactivation of energy gained by molecules in their excitation by electron impact to
low-lying singlet states has been obtained from an analysis of changes in the fluorescence spectra of these molecules. It
is shown that there is a significant difference in the formation of fluorescence spectra when free molecules are excited by
optical radiation and by electrons. It contrast to optical excitation, the interaction of an electron with a molecule is nonselective
in character. All electronic states have a chance to be excited, which results in ensembles of emitting molecules with a different
store of vibrational energy, and these ensembles each contribute to the fluorescence spectrum.
Deceased.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 216–223, March–April, 1998. 相似文献
10.
The possible use of a simplified UV absorption spectroscopic method for dosimetry of bioactive antirachitic UV radiation has
been analyzed. The method is based on the observation of the phototransformation kinetics of the provitamin D3 primary molecule in ethanol (in vitro vitamin D3 synthesis model) by measuring the decrease in the optical density at a fixed wavelength during UV exposure. The method can
be used successfully for artificial UV sources with a constant radiation spectrum. However, such a technique turns out to
be inapplicable to solar UV dosimetry in view of the variability of the solar UV spectrum that results in a varying rate of
formation of irreversible photoproducts.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 256–260, March–April, 2009. 相似文献
11.
V. A. Lapina P. P. Pershukevich A. E. Dontsov M. V. Bel’kov 《Journal of Applied Spectroscopy》2008,75(1):53-63
The spectra and kinetics of fluorescence of two-component solutions of the chlortetracycline (CHTC)-DOPA-melanin (melanin
or ME) system in water have been investigated. The data obtained have been compared to similar data for solutions of CHTC-melanosome
from bull eye (MB), which contains natural melanin, in K-phosphate buffer at pH 7.4. The overall results indicate the occurrence
of complexation between molecules of CHTC and ME as they are being excited. The studies of complexation in the solution of
CHTC-MB in the buffer are complicated by the formation of a CHTC-buffer complex. The effect of optical radiation in the range
330–750 nm on the CHTC-ME complex shows selectivity: the greatest change in the spectrum occurs when the wavelength of the
exciting radiation coincides with the long-wavelength band maximum of the fluorescence excitation spectrum of the CHTC-ME
complex in aqueous solution. In this range, CHTC and especially ME show high photochemical stability. The nature of the radiation
effect on the studied compounds in the hard UV range (λ < 330 nm) differs greatly from that in the range 330–750 nm. It is
apparently accompanied by significant photochemical transmutations of all system components. By comparing the characteristics
of the CHTC-ME systems with those of the related drug doxycycline (DC-ME), the conclusion has been made that the chlorine
atom plays a vital role in formation of the short-wavelength band in the fluorescence spectrum of the CHTC-ME complex.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 52–62, January–February, 2008. 相似文献
12.
I. Kh. Abdukadyrova 《Journal of Applied Spectroscopy》2006,73(4):557-561
IR spectroscopy has been used to study the process of structural damage and changes in some characteristics of fused silica
irradiated by fast neutrons over a very broad fluence range (1017–1021 cm−2). Features of the change in spectral characteristics of the bending and stretching vibrations of the bridge bonds have been
identified, and also a comparative analysis has been carried out with radiation-induced changes in a series of optical spectra
in the UV and visible regions, and structural parameters and other characteristics of wafers irradiated by different fluences.
A correspondence has been established between the features of the radiation-induced changes in the optical, luminescence,
and structural properties, and extremal points have been observed on the dose dependences. Based on the results obtained,
a mechanism of radiation-induced rearrangement of the silica structure is suggested.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 494–497, July–August, 2006. 相似文献
13.
Characteristics of nonlinear optical phenomena in reflection of light at the interface with photorfractive crystals having
photovoltaic nonlinearity are studied. it is shown that under total reflection, hysteretic behavior of the reflection coefficient
is possible as a function of the incident radiation intensity or the angle of incidence. It is important that previously required
threshold intensities are rather low (≤1 W/cm2) in comparison with the known case of reflection from media with Kerr nonlinearity. The present results are of doubtless
interest in view of the development of possible devices for controlling laser radiation.
Interdepartmental Institute of Advanced Training of Personnel in New Trends in Engineering and Technology at the State Polytechnical
Academy of Belarus, 77, Partizanskii Ave., Minsk-107, 220600 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 6, pp. 915–920, November–December, 1998. 相似文献
14.
E. K. Naumenko 《Journal of Applied Spectroscopy》1998,65(3):434-441
The spectral dependences of the optical characteristics governing radiation transfer in scattering media are analyzed within
the wavelength range of 0.4–14 μm for three types of aerosols. The wavelength ranges where approximate methods of calculation
of frequency-contrast characteristics are applicable are established; the corresponding limitting masses of aerosol particles
in a layer per unit of surface area are determined for which approximate methods provide acceptable accuracy.
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 419–425 May–June, 1998. 相似文献
15.
S. N. Ivanov E. Yu. Loktionov Yu. S. Protasov Yu. Yu. Protasov 《Journal of Applied Spectroscopy》2009,76(5):738-742
We describe an optical diagnostics module and the instrumental and methodological features of ultrahigh vacuum experiments
investigating the optical characteristics of condensed media in the short-wavelength (hv ~ 3.5–25 eV) range of the spectrum of probing synchrotron radiation. We give a brief presentation of the results of an experimental
determination of the spectral dependence of the luminescence quantum yield and the luminescence excitation spectrum of ablatable
polymer dielectrics on the Kurchatov synchrotron radiation source at values of the probing radiation power density (I
0 ~ 1012 photons/cm2∙sec) that are below threshold for extended surface vaporization and a surface temperature of the condensed targets equal
to 77–300 K. 相似文献
16.
The spectra of transmission and reflection are measured in the region of 0.4–2.5 μm on thin silver selenium indate films obtained
by means of pulse laser vaporization. The magnitudes of the refractive index and absorption coefficient are calculated. The
energies of interband transitions and the values of crystalline and spin-orbit splitting are determined. The experimental
results for the AgInSe2 films agree with the data for bulk crystals.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 512–514, July–August, 2000. 相似文献
17.
The influence of the tuning of the radiation frequency of quantum-well heterolasers within the limits of their amplification
band on the output laser radiation parameters at different frequencies of pump-current modulation has been numerically simulated
using two optical models of an active medium under the assumption that the excess of the invariable component of the pump
current over its threshold value at any point of the amplification band is constant. It has been established that the amplitude-detuning
characteristics of the lasers studied are linear at high current-modulation frequencies and nonlinear at medium ones. The
behavior of the nonlinear spectral response of a laser diode is explained by its multiresonance structure and is mainly determined
by the ratio between the pump-current modulation frequency and the maximum resonance frequency of the laser.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 473–478, July–August, 2005. 相似文献
18.
Dependences of the refractive indices on the proton concentration in H:LiNbO3 waveguides 总被引:1,自引:0,他引:1
Proton-exchanged optical waveguides in lithium niobate crystals exhibit a rich variety of structures and phases. It is established
that seven HxLi1−x
NbO3 crystalline phases with a lithium niobate structure may form under various conditions of proton exchange and post-exchange
annealing. A method is proposed to determine the proton concentration in the various phases identified. Relationships are
established between the structural parameters, the proton concentration, and the ordinary and extraordinary refractive indices
of various HxLi1−x
NbO3 crystalline phases. The results can explain various optical phenomena observed in proton-exchanged waveguides and permit
prediction of the characteristics of light-guide structures.
Zh. Tekh. Fiz. 69, 47–57 (March 1999) 相似文献
19.
Xiaomiao Hou Xiaoling Zhang Yan Fang Shutang Chen Na Li Qi Zhou 《Journal of nanoparticle research》2011,13(5):1929-1936
1-Hexadecylamine (HDA)-capped Au and Ag nanoparticles (NPs) have been successfully prepared by a one-pot solution growth method.
The HDA is used as both reducing agent and stabilizer in the synthetic process is favorable for investigating the capping
mechanism of Au and Ag NPs’ surface. The growth process and characterization of Au and Ag NPs are determined by Ultraviolet–visible
(UV–vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). Experimental results demonstrate
that the HDA-capped Au and Ag NPs are highly crystalline and have good optical properties. Furthermore, surface-enhanced Raman
scattering (SERS) spectra of 2-thionaphthol are obtained on the Au and Ag NPs modified glass surface, respectively, indicating
that the as-synthesized noble metal NPs have potentially high sensitive optical detection application. 相似文献
20.
O.R. Musaev O.S. Kwon J.M. Wrobel D.-M. Zhu M.B. Kruger 《Applied Surface Science》2008,254(18):5803-5806
An InP wafer was irradiated in air by a series of UV pulses from a nitrogen laser with fluences of 120 mJ/cm2 and 80 mJ/cm2. These fluences are below the single-pulse ablation threshold of InP. Over the studied region the distribution of the radiation intensity was uniform. The number of pulses varied from 50 to 6000. The evolution of the surface morphology and structure was characterized by atomic force microscopy, optical microscopy and Raman spectroscopy. The relationship between mound size and the number of pulses starts out following a power law, but saturates for a sufficiently high number of pulses. The crossover point is a function of fluence. A similar relation exists for the surface roughness. Raman spectroscopic investigations showed little change in local crystalline structure of the processed surface layer. 相似文献