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1.
W.?A.?Pisarski ?.?Grobelny J.?Pisarska R.?Lisiecki G.?Dominiak-Dzik W.?Ryba-Romanowski 《Laser Physics》2010,20(3):649-655
Rare earth doped lead borate glasses and transparent glass-ceramics have been studied using optical spectroscopy. Based on
the absorption, emission and its decay and the Judd-Ofelt calculations, several radiative and laser parameters for Ln
3+ (Ln = Pr, Nd, Eu, Dy, Er, Tm) were evaluated. The large values of luminescence lifetime, quantum efficiency of excited state
and room temperature peak stimulated emission cross-section suggest efficient laser transitions of Ln
3+ ions in lead borate glasses. The obtained results indicate that lead borate glasses and glass-ceramics containing Ln
3+ ions are promising host matrices for solid-state laser applications. 相似文献
2.
3.
V. N. Gridnev 《JETP Letters》2011,93(3):161-165
The dynamics of the coherent superposition of exciton states in a semiconductor quantum well excited by the joint action of
two successive light pulses with the time interval between them t
12 has been theoretically studied. The dependences of the amplitude and initial phase of the quantum bits on t
12 have been found. It has been shown that the time dependence of the Kerr rotation of the reflected probe pulse is determined
not only by the dynamics of the excited state, but also by the optical properties of the heterostructure containing the quantum
well. The dependence of the decay rate of the excited state on t
12 has been predicted. 相似文献
4.
Abstract The characteristics of stored ions in a Kingdon trap have been investigated. The charge distribution of stored ions was measured by a time of flight (TOF) mass spectrometer. Storage of Arq+ (q = 1, 2, 3, 4) produced by electron beam irradiation has been confirmed. The dependences of Ar ion yields on the trapping potential and storage time have been systematically studied. Applying a voltage to end plates is very important for the storage of ions. Remarkable oscillations of the ion yields are found in the decay curves as a function of storage time for Ar+, Ar2+ and Ar3+ indicating periodical motion of each ion group about the central wire. The three dimensional orbits of ions in the trap are analysed by a computer calculation to understand the experimental results. 相似文献
5.
Yuan Liu 《Hyperfine Interactions》2014,227(1-3):85-99
The development of a resonant ionization laser ion source (RILIS) for the production of isotopically pure radioactive ion beams is reported. The application of the laser ion source calls for high elemental selectivity, high efficiency, and fast release of short-lived isotopes. A hot-cavity ion source and three Ti:sapphire lasers pulsed at a 10 kHz rate are employed for the RILIS. The Ti:sapphire lasers have been upgraded with individual pump lasers to eliminate intracavity Pockels cells and output losses due to synchronization delays. The development of ionization schemes for a wide range of elements is important to the success of Ti:sapphire-laser-based RILIS. In off-line studies with stable isotopes, resonant ionization of 14 elements has been studied, leading to new ionization schemes for ten elements. The absolute ionization efficiency of the hot-cavity RILIS has been measured to range from 0.9 % to 40 % for different elements. The mechanisms for ion transportation and confinement in the hot-cavity ion source have been studied using the temporal profiles of the laser-ionized ions. The hot-cavity RILIS has provided beams of neutron-rich $^{83,85,86}$ Ga isotopes for beta decay studies and enabled the first measurement of the beta decay of the exotic $^{86}$ Ga. 相似文献
6.
A. Jokinen J.C. Wang J. Äystö P. Dendooven S. Nummela J. Huikari V. Kolhinen A. Nieminen K. Peräjärvi S. Rinta-Antila 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):9-12
Beta decay of a refractory isotope 118Rh produced in symmetric fission and mass separated by the ion guide technique has been applied for the study of low-lying
excited states of 118Pd. The yrast band in 118Pd has been observed up to a 6+ state and the lowest states of the asymmetric γ-band have been identified. The measured half-life of 118Rh is (300±60)ms. The systematics of the excited states in neutron-rich Pd-isotopes implies the saturation towards an O(6) symmetry at N = 70.
Received: 19 June 2000 / Accepted: 1 August 2000 相似文献
7.
本文利用飞秒激光泵浦-探测质谱和离子成像研究了NO_2分子的超快解离动力学.结果表明NO~+离子的动能释放包含两个部分,分别对应的能量是0.05和0.25 eV,并且指认了它们叫能的解离通道.NO~+离子通道分辨的瞬态测量提供了区分超快解离路径贡献的方法,不同动能释放的离子信号变化曲线可以通过双e指数函数进行拟合.其中衰减时间为0.25 ps的快速变化部分产生于里德堡态的演化.变化较慢的信号部分是山两个竞争的通道产生的,其中一个通道是吸收一个400 nm光子到A~2B_2激发态,它的衰减寿命是30 ps;另一个慢的通道是吸收三个400 nm光子到一个价电子类型的里德堡态,它的衰减寿命是短于7.2 ps.通道和时间分辨的实验测量对于区分分子复杂的超快解离动力学具有非常大的潜力. 相似文献
8.
Energy transfer from both Coumarin 120 (C120) and p-Bis(o-methylstyryl)-benzene (Bis-MSB), energy donors, to coumarin 7(C7) (acceptor) individually has been studied by steady-state emission measurements in methanol. The dye laser characteristics of the above-mentioned dyes have also been studied with respect to the energy transfer mechanism in the same solvent using a pulsed nitrogen laser as a pumping source. The large values of the critical transfer distances, R0, indicate that the dominant mechanism responsible for energy transfer is due to long-range dipole–dipole interaction between the excited donor and ground state acceptor molecule. Both photophysical and photochemical stability of the donors has been examined under the effect of N2 laser pumping. 相似文献
9.
Sven Mannervik 《Hyperfine Interactions》2000,127(1-4):237-245
Collinear ion beam laser spectroscopy has been utilized in the ion storage ring CRYRING in order to measure lifetimes of metastable
states in singly charged ions. The laser light has been used for selective probing of the population decay of individual fine
structure or hyperfine structure states. With the use of a mechanical shutter, time resolved studies could be performed with
millisecond resolution. In another experiment, the cw laser light was used to optically pump stored ions from the ground state
into a specific metastable state. With most of the stored ions in the metastable state, direct observation of the decay of
the forbidden transition from the metastable state to the ground state could be observed passively. Measurements of metastable
lifetimes in Ca+, Sr+, Xe+ and Eu+ will be discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
R. Grasser K. Hermanns A. Scharmann 《Zeitschrift für Physik A Hadrons and Nuclei》1972,250(3):248-253
The decay characteristics of ZnS/(10?4) Cu have been investigated by ion pulse excitation. The excitation density could be varied by using ions of different masses. The decay is exponential. The decay times depend on the ion pulse duration and on the penetration depth of the used ions. The green emission shows two different decay times. The intensity of the slower component of the green emission could be altered by excitation with UV-light before decay measurement. In the case of the slower component of the green emission we suppose an interaction between the excited states of the luminescence centres and energetically deep electron traps. 相似文献
11.
Lakshman S. V. J. Moorthy L. Rama 《Applied Physics A: Materials Science & Processing》1985,38(4):285-291
The optical absorption spectra of triply ionized neodymium and erbium ions in POCl3SnCl4 laser liquid have been studied for the first time in the UV-VIS and NIR regions. Spectroscopic and Judd-Ofelt intensity parameters are evaluated from the observed band positions and their intensities. Radiative lifetimes and the luminescent branching ratios for the excited fluorescent levels of Nd3+ and Er3+ ions are theoretically estimated and the possible laser transitions are indicated. From the observed splittings of certain bands in the second-derivative spectrum of the Nd3+ ion, the crystal field (A
20,A
40) parameters are evaluated assumingC
3h symmetry for the ion. 相似文献
12.
The hf pulse excited Ar + N2 mixtures and early afterglow are investigated at total pressures from 266 to 1995 Pa using nitrogen of 0·05–0·5% concentration. The time-resolved intensity of Ar I atomic lines and N2 (2nd pos., 1st pos. and 1st neg.) band systems exhibit an intense early afterglow (0·3 ms). Both the decay of electron densityn
e and that of molecular Ar
2
+
ions and enhancement of coefficient of dissociative recombination due to electron temperature decrease after the pulse lead to the formation of characteristic secondary maximum of Ar I spectral line and N2 molecular band intensities in the momentt
m after cut-off the pulse. The values oft
m(B3g)>t
m(C3u)>t
m(Ar I) decrease with increasing total pressure and increase with growing concentration of N2 in Ar. In the afterglow period the Ar
2
+
dissociatively recombine in 5p and 4p Ar states. As a result of radiative transitions the metastable Ar (3P2,0) atoms are formed which consequently due to collisions with N2 molecules create electronically excited N2. With increasing nitrogen concentration this effect becomes less pronounced and at concentration of N2 greater than 0·5% it is negligible. 相似文献
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The method of molecular dynamics has been employed to study the autocorrelation functions (ACF's) of the linear velocity and of the angular momentum for two two-dimensional systems of diatomic molecules. The anisotropic potential used is built from four atom-atom interactions. These are either purely repulsive (R), or repulso-attractive (LJ). Emphasis has been put on the long-time behaviour; for this we have used large systems (1600 molecules). The density lies in the intermediate range. The linear velocity ACF exhibits, for system R, an initial decay which is exponential and whose characteristic time has been checked to be of the order of the mean ‘collision’ time. For system LJ (where collisions cannot be usefully defined) the decay does not follow a simple law, and lies above a single exponential. After an intermediate regime which lasts a long time-span for both systems, the ACF's adopt a t -1 decay in agreement with theoretical predictions based on hydrodynamics or other approaches. The mean square displacement has also been extracted from the data. Its ratio to time, i.e. the apparent coefficient of diffusion, increases logarithmically with time, so that the two kinds of data are in accord. This asymptotic regime starts after about 11 collision times for the repulsive system, and about as soon for the other one. The angular momentum ACF's, after an initial decay which is closer to an exponential for system R than for system LJ, adopt a t -3 behaviour for a very long time-span; this possibly masks a final t -2 decay predicted by several theories based on the coupling of the intrinsic momentum with the vorticity of the fluid. 相似文献
16.
M. Seliverstov A. Andreyev N. Barré H. De Witte D. Fedorov V. Fedoseyev S. Franchoo J. Genevey G. Huber M. Huyse U. Köster P. Kunz S. Lesher B. Marsh B. Roussière J. Sauvage P. Van Duppen Yu. Volkov 《Hyperfine Interactions》2006,171(1-3):225-231
Mean-square charge radii and magnetic moments have been measured for the neutron deficient lead isotopes, 182–190Pb. The measurement was performed at the ISOLDE online mass separator, using the in-source resonance ionization spectroscopy
technique. The wavelength of the first excitation step for the resonance ionization laser ion source (RILIS) was scanned over
the resonance(s) whilst the α- and γ-ray spectra from the decay of the Pb isotopes were recorded as a function of the wavelength. The isotope shift and, in the
case of odd-A isotopes, the hyperfine splitting were deduced. The rms-charge radii of the very neutron deficient Pb isotopes follow the
smooth trend of the heavier isotopes. This finding indicates a spherical shape for the lead ground states at the neutron mid-shell
(N = 104), where the excitation energy of the oblate 0+ state in the even isotopes reaches its minimum. 相似文献
17.
R. J. M. da Fonseca L. P. Sosman A. Dias Tavares Jr. H. N. Bordallo 《Journal of fluorescence》2000,10(4):375-381
Interest in 3d transition metal impurities in ionic crystals has increased due to their important role in the laser activity of these materials. Moreover, recent advances in tunable solid-state lasers and high-power semiconductor laser diode arrays have generated a strong interest in investigating new compounds that emit in the visible and near-infrared spectral regions. In particular, many optical studies have been devoted to Cr3+-doped fluoride crystals as a consequence of the high quality of some Cr3+-based laser materials. In the present investigation, the low-temperature emission spectra of Cr3+ ions in the hexagonal elpasolites Cs2NaAlF6 and Cs2NaGaF6 have been measured. Each compound has two crystallographically inequivalent octahedral sites for the Al3+ and Ga3+ ions that can be occupied by Cr3+ ions. For both materials, the luminescence spectrum presents two zero-phonon lines accompanied by a well-defined vibrational structure. The different peaks of the emission broad band are described in terms of phonons of the lattice and normal modes of the octahedral complex [CrF6]3–. A detailed analysis of the vibrational structure observed leads to the conclusion that the 2
E and 4
T
2 excited states of the [CrF6]3– ion are displaced along the e
g and a
1g
and probably the t
2g
coordinates. 相似文献
18.
V. F. Zelenskij I. M. Neklyudov I. S. Martynov A. N. Morozov S. V. Pistryak V. F. Rybalko 《辐射效应与固体损伤》2013,168(1-3):31-43
Abstract Electron diffraction studies have been made of polycrystalline Ni films irradiated with well separated beams of ions of different nature, namely ions of inert (He+, Ne+, Ar+, Kr+, Xe+) and reactive (N+ and O+) gases. The Ni films were prepared under vacuum conditions (P? 3·10?6Pa during evaporation) preventing an appreciable contamination of the films with impurities. The samples were irradiated at T? 300 K with ion beams of energies from 10 to 100 keV in the dose range between 5·1016 cm?2 and the value leading to sample destruction. Irradiation with noble gas ions revealed no phase transitions in the Ni films. A similar result was obtained in irradiation of Fe and Cr films with He+ ions. The bombardment of Ni films with reactive gas ions does cause changes in the lattice structure of the samples under study, depending on the nature of the bombarding ions. The N+ ion bombardment gives rise to the hcp phase with the lattice parameters typical of the Ni3N compound, and the O+ ion bombardment results in the fcc phase with the NiO-type parameter. The conclusion is drawn on the chemical origin of the phase transformations in the Ni films under ion bombardment. The necessity of revising the concept about the polymorphous nature of phase transformations induced in the films of transition metals by ion bombardment is substantiated. 相似文献
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20.
Roderich Keller 《辐射效应与固体损伤》2013,168(1-4):201-206
Duoplasmatrons have been employed at GSI as accelerator sources of multiply charged heavy ions, but extensive experience was collected also with singly charged noble gas ions. Other ion species can be produced from volatile compounds. provided that the cathode is protected from aggressive vapours by an additional noble gas. In a second source modification. the sputter duoplasmatron, ions are directly obtained from solid material. Recently the GSI-duoplasmatron has been equipped with plasma expansion cups in order to raise the ion current output. Generally, at least a factor of three is gained in beam intensity and other aspects of source performance are improved, too. A new cathode design considerably enhances life-time and reliability, permitting uninterrupted operation for a few hundred hours. Tables of measured ion beam currents are given. 相似文献