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1.
We have studied the effect of lead dopant on the optical absorption, photoluminescence, and x-ray luminescence spectra, and the scintillation characteristics of CdI2 at room temperature. The crystals for the study were grown by the Stockbarger-Bridgman method. Activation of CdI2 from the melt by the compound PbI2 leads to the appearance in the absorption spectra in the near-edge region of an activator band at 395–405 nm, which is interpreted as an A band connected with electronic transitions from the 1S0 state to the 3P1 levels in the Pb2+ ion. For x-ray excitation, CdI2:Pb2+ crystals with optimal dopant concentration (∼1.0 mol%) are characterized by a light yield with maximum in the 570–580 nm region that is an order of magnitude higher than for CdI2 crystals in the 490–500 nm band. For α excitation, the radioluminescence kinetics for cadmium iodide is characterized by a very short (∼0.3 nsec) rise time and fast decay of luminescence, with τ1 ≈ 4 nsec and τ2 = 10–76 nsec. Depending on the conditions under which the crystals were obtained, the fast component fraction is 95%–99%. The crystal is characterized by a similar scintillation pulse in the case of excitation by x-ray pulses. The radioluminescence pulse shape for CdI2:Pb in the decay stage is predominantly exponential, with luminescence decay time constants τ1 ≈ 10 nsec and τ2 = 200–250 nsec. This system is characterized by low afterglow, at the level for the Bi4G3O12 scintillator. We have demonstrated the feasibility of using CdI2:Pb as a scintillator for detecting α particles. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 825–830, November–December, 2008.  相似文献   

2.
We have studied an optical parametric oscillator (OPO) with an unstable telescopic cavity, placed inside the cavity of an actively Q-switched multimode Nd3+:KGW pump laser. We used a KTP crystal as the nonlinear medium for the OPO. We have compared the emission characteristics of OPOs with unstable telescopic and planar cavities. We have established that compared with the planar cavity, the unstable cavity reduces the OPO beam divergence and improves the spatial distribution of the radiation energy in the far wave zone. Based on our investigations, we have designed a compact eye-safe (λ = 1.578 μm) laser source with natural cooling, emitting (for electrical pumping energy 7.3 J) pulses with pulse energy 22 mJ and pulse duration 6 nsec. The FWHM beam divergence for the source is no greater than 3.5 mrad. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 254–259, March–April, 2006.  相似文献   

3.
Thin films of solid xenon have been excited by a pulsed electron beam with electron energies of 300 eV and pulse lengths down to 5 nsec at low current. For the main luminescence band of solid xenon (λ ≈ 1750 Å) two decay times have been observed. The short decay time (3 ± 1 nsec) is independent of temperature between 4 K and 30 K, whereas the long decay time decreases from 900 ± 50 nsec at 4 K to 150 ± 50 nsec at 30 K.  相似文献   

4.
The generation properties of an optical parametric oscillator (OPO) with a three-mirror ring resonator have been investigated under conditions of a pulsed pump by multimode radiation from a Nd3+:YAG laser. KTP crystals were used as the OPO nonlinear medium. At pump energies up to 100 mJ, decreasing the diameter d of the Nd3+:YAG laser beam causes a decrease in OPO radiation divergence and an increase in the generation efficiency at λ = 1.571 μm despite a decrease in the differential efficiency. At d = 2.25 mm and a KTP crystal total length of 40 mm, the efficiency of the pump conversion to the signal-wave pulse reaches 36.5%. Based on the traveling-wave OPO, a compact, highly effective, eye-safe laser source radiating pulses of up to 35 mJ in energy, 11 nsec in duration, and 10 Hz in repetition rate at electrical pump energy of ≤ 8 J is developed. At the 86.5% level of the total pulse energy, the source-beam divergence does not exceed seven diffraction limits. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 516–523, July–August, 2008.  相似文献   

5.
We have studied the radiation output parameters for an erbium glass laser, lasing at a wavelength of 1.54 μm, with passive Q-switching by means of a cobalt-containing magnesium aluminosilicate sitall compared with a saturable absorber based on a magnesium aluminum spinel crystal with cobalt ions. We have shown that the output characteristics of the laser emission when using sitall are not inferior to the analogous characteristics of a laser based on a spinel crystal, and are practically independent of the temperature of the saturable absorber in the range 0°C–80°C. The duration (energy) of the output pulses was 70 nsec (∼4 mJ), the energy dispersion of the radiation pulse relative to the average value was no greater than 3%, the beam divergence was 2.8 mrad, the laser beam quality factor was M2 = 1.2. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 126–131, January–February, 2007.  相似文献   

6.
A resonance-Raman-scattering multifrequency laser spectrometer operating in a wide spectral range (355–750 nm) and making possible the recording of both stationary Raman spectra and spectra with a time resolution of up to 100 psec in the time interval of 0–50 nsec has been developed. The spectrometer has been used with advantage for the study of the excited states of molecules of metalloporphyrins in solutions and processes of interaction of model metalloporphyrins with DNA and DNA-modeling polynucleotides. To whom correspondence should be addressed. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus 68, F. Skorina Ave., Minsk, 210072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 726–733, September–October, 1999.  相似文献   

7.
A rubidium laser pumped on the 52S1/2–52P3/2 D2 transition by a pulsed dye laser at pump intensities exceeding 3.5 MW/cm2 (>1000 times threshold) has been demonstrated. Output energies as high as 12 μJ/pulse are limited by the rate for collision relaxation of the pumped 2P3/2 state to the upper laser 2P1/2 state. More than 250 photons are available for every rubidium atom in the pumped volume during each pulse. For modest alkali atom and ethane spin–orbit relaxer concentrations, the gain medium can only process about 50 photons/atom during the 2–8 ns pump pulse. At 110°C and 550 Torr of ethane, the system is bottlenecked in the 2P3/2 state and all of the incident photons cannot be absorbed. The output energy is linearly dependent on pump pulse duration for a given pump energy. The highly saturated pump limit of the recently developed three-level model for diode pumped alkali lasers (DPALs) is developed. The system efficiency based on absorbed photons approaches 36% even for these extreme pump conditions.  相似文献   

8.
It has been found that on exposure of specimens of synthetic opal to UV radiation, luminescence is excited in them (337 nm) that has spectral maxima at 400 and 500 nm. Its duration at half-height of a pulse is 9 nsec, and there is a weak slow component with τ ∼ 1 μsec. The spectrum and intensity of the luminescence depend on the duration of irradiation and temperature. The luminescence bands revealed relate to two individual luminescence centers, namely: the shortwave one, caused by the luminescence centers formed in the bulk of the opal, and the longwave one, due to those formed on the opal surface. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 622–626, September–October, 2005.  相似文献   

9.
We have experimentally studied the lasing characteristics of an eye-safe optical parametric oscillator (OPO) with an unstable telescopic cavity when it is placed inside (intracavity OPO) and outside (extracavity OPO) the plane-parallel cavity of a pulsed, nearly single-mode KGW:Nd pump laser. We used a KTP crystal as the nonlinear medium for the OPO. We have shown that the intracavity OPO has the higher lasing efficiency. We have observed that the distribution of nonlinear losses introduced by the intracavity OPO, nonuniform over the cavity cross section, leads to an increase in the diameter and divergence of the radiation beam from the pump laser and a dependence of its temporal lasing dynamics on the transverse beam coordinate. We propose a physical model qualitatively explaining the spatial and temporal lasing dynamics of a radiation source with an intracavity OPO. Both OPO versions generate beams of radiation with about the same divergence. When the KGW:Nd laser has an electrical pumping energy of 7.3 J and a cavity length of 77 cm, the intracavity OPO and the extracavity OPO emit pulses with energies of 14.5 mJ and 12.0 mJ and duration 18 nsec and 13 nsec respectively. The divergence of the eye-safe radiation (λ = 1.578 μm) at 86.5% of the total pulse energy is no greater than 5.5 mrad for an OPO output beam diameter of = 2 mm. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 535–543, July–August, 2006.  相似文献   

10.
The results of experiments with a three-ring large-area diode that were conducted on an MIG pulse generator are reported. The MIG generator makes it possible to produce in a matched load electrical pulses up to 2 TW in power with an FWHM of 50–60 ns (1.2–1.4 TW and 80–90 ns in our experiments). In the operating mode of the generator, the current amplitude through the load is 2 MA (the current of a relativistic electron beam) at a diode voltage of ≈ 500 kV. As a load, a large-area vacuum diode with three ring-shaped cathodes is used. It is shown that about 20% of the energy stored in the capacitor bank can be converted to the energy of a relativistic electron beam by matching the output resistance of the MIG generator to the load resistance. When the beam slows down on a condensed foil target, the parameters of the resulting source are the following: the mean energy of X-ray quanta is ≈ 70 keV; irradiated area, 500 cm2; pulse FWHM, 65 ns; energy flux in the spectrum, 2 J/cm2; and percentage of X-ray radiation (10–100 keV) in the flux, ≈ 50%.  相似文献   

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