Measurement of the collisional transition rate between the hydrogen levels n = 3 and n = 4

The ratio of the collisional transition rate C₄₃ and the total loss rate V₄ of the level n = 4 has been measured by means of dye-laser fluorescence in a rf hydrogen plasma. In a further experiment using a nitrogen-laser-pumped dye-laser (with pulses short compared to the life time of the n = 4 level), the total loss rate V₄ of this level has been determined by observing the exponential intensity decay of the H_β line. From the results of these two experiments, the excitation rate C₄₃ is obtained. Agreement with theoretical values is found.     

Angular distribution of electron emission from atomic hydrogen by bare ion impact

A series of silver nanoparticle embedded in erbium-doped tellurite glasses were synthesized using a one step melt-quenching method. Density and refractive index of glasses were measured. Thermal and optical characterizations were performed and plasmon bands of elliptical nanoparticles were observed. An enhancement of green (525 and 550 nm) and red (632 nm) lines in luminescence spectra of Er³⁺-doped silver-embedded tellurite glass was recorded and explained by energy transfer mechanism from silver nanoparticles to erbium ion in addition to enhanced local field in vicinity of metallic nanoparticles in the glass. The presence of nanoparticles was confirmed by transmission electron microscopy imaging and reduction of silver ions to silver neutral particles discussed through the redox potential estimation in probable reactions. Silver-erbium co-doped tellurite glass exhibits strong novel optical properties which nominate it as the promising glass for laser, color displays, and photonic applications.     

Angular and polarization correlations in the (n, γ) reaction

Parity-odd and parity-even correlations in neutron radiative capture are considered. We discuss the correlation mechanisms, their magnitudes, dependence on neutron energy and averaging over the final nuclear states. The total number of correlations when s- and p-wave neutron capture and E1 and M1 γ-transitions are taken into account, is equal to 17 (8 parity odd and 9 parity even). The correlations in the integrated γ-quantum spectrum are divided into three classes which contain information about different properties of the compound nucleus.     

Angular correlation of photons emitted from an excited quantum well

We study the angular correlation of single photons emitted from excited semiconductor quantum wells. The considered physical system is described in terms of two subsystems, the electronic part constituting the bath and the photonic part constituting the bathed subsystem, both being coupled by the light-matter interaction. From the master equations describing the coarse-grained Markovian evolution of the photonic subsystem, we derive the corresponding equations of motion for the photonic angular correlation functions. These equations are solved in the stationary, low-density limit. Experimentally, the angular correlations can be assessed by studying the interference of light emitted in different directions. In agreement with recent experimental results, we find that for ordered quantum wells angular correlations exist only in emission directions for which the projections of the photon momenta onto the plane of the quantum well are equal. This feature is a direct consequence of the Bloch character of the electronic states in an ordered quantum well. Thus the experimental study of the angular correlations of emitted photons may provide an interesting diagnostic tool to reveal the presence of disorder in semiconductor heterostructures and to characterize its influence on the electronic states near the band edges.     

Rayleigh scattering fromn=2 states of atomic hydrogen

Exact analytic results are presented for the elastic scattering of photons from excited hydrogen atoms in then=2 states. The general form of the matrix elements required is inferred from previous work on the scattering by a completen=2 shell of a model atom, and is expressed in terms of one hypergeometric function of the Gauss type. The low-energy behavior of the matrix elements is discussed and new negative-order sum rules are derived. The cross sections were computed to a high degree of accuracy for values of the photon energy both below and above the photoionization threshold for then=2 states. Detailed results are given for near-resonance scattering (i.e., in the vicinity of Balmer frequencies), due to its relevance for the diagnostics of neutrals in fusion plasmas.     

GeⅩⅪ-SeⅩⅩⅢ离子n=3,Δn=0跃迁谱线和振子强度的计算

用HFR方法对CaⅨ-KrⅩⅩⅤ离子3s2,3s3p,3s3d,3p2组态能级结构进行了理论计算.在已有实验研究的基础上,通过分析离子能级沿等电子序列的变化规律,运用最小二乘拟合方法预言计算了GeⅩⅪ-SeⅩⅩⅢ离子3s2,3s3p,3s3d,3p2组态14条精细结构能级值.在此基础上,进一步计算了GeⅩⅪ-SeⅩⅩⅢ离子3s2-3s3p,3s3p-3s3d和3s3p-3p2跃迁的23条谱线波长和相应的振子强度.计算结果与已有的实验值十分吻合,波长的最大不确定度为0.008 nm.     

Interference between different photons from two incoherent sources

Intensity interference fringes are observed by using two incoherent light-emitting diodes. It is verified that even an incoherent light interferes with another one.     

Angular distribution of protons emitted from the hydrogen plasma focus

Angular distribution of emitted protons was measured. The protons were detected with NTD LR-115 placed at the specially constructed semi-spherical holder, which contains 17 different pinhole cameras. The mechanism of proton acceleration and emission are studied theoretically and experimental results are compared with theoretical predictions.     

解除氢原子能级(n=3)的简并

讨论氢原子能级在两个正交线性非均匀电场中的分裂。     

Angular distribution of protons from the reaction Co59(n,p) Fe59 forE n ∼6·3 MeV

The energy and angular distributions of protons in the reaction Co⁵⁹ (n, p) Fe⁵⁹ have been measured forE _p =6·3 MeV. The results show the presence of other mechanism than compound nucleus.The authors would like to thank Miss Sestáková and Mrs. Sirová for careful scanning of plates and for help in part of the treatment of results.     

离子化程度对硼取代富勒烯C19Bn+（n=0-3）体系储氢性能的影响

本文采用密度泛函理论方法,研究了氢气分子在硼取代富勒烯C19Bn+（n=0-3）表面的非解离吸附态、化学吸附态、及吸附态之间转换过渡态的结构和能量,得到了吸附态之间转换反应的势能面. 研究表明通过调整体系的离子化电荷可以调整吸附位点的电荷布居数,随着硼取代富勒烯离子化体系C19Bn+的吸氢活性位点电荷布居数增大,氢分子被极化的程度以及氢分子在材料表面的吸附能均逐渐增大,同时改变电荷布居数也对氢气分子在表面吸附态间转变势垒高度产生了量级为几个Kcal/mol的影响. 希望我们的研究能够对富勒烯储氢的进一步发展提供参考.     

Intensities of helium Stark lines in the region of levels anticrossing between n = 6 and n = 7

Studies of intensities of Stark lines of atomic He have been performed. The applied fields were high enough that shifts of the upper levels of the observed transitions became larger than the separation distance between levels with different principal quantum numbers. Overlapping of structures belonging to neighboring principal quantum numbers leads to levels anticrossing effects, what is reflected in variation of intensities of the observed spectral lines. Using the density matrix theory, calculations of the line intensities have been performed. By matching the superpositions of the excited states in the theoretical calculations we can follow the results of observation. Computer simulations have been performed for the observed levels anticrossing region between n = 6 and n = 7 in the second triplet series (2³P–n³Q, Q = S, P, D, ...).     

Angular distribution of photoelectrons from atomic oxygen at 736 Å and 584 Å

The angular distributions of photoelectrons ejected in the process $\text{O}\text{(2}\text{p}{}^4{}^3\text{P}\text{) + hv →}\text{O}{}^{\mathrm{+}}\text{(2}\text{p}{}^3{}^4\text{S}\text{) +}\text{e}$ and $\text{O}{}^{\mathrm{+}}\text{(2}\text{p}{}^3{}^2\text{D}\text{) +}\text{e}$ have been measured at the 736 Å NeI resonance line and at the 584 Å HeI resonance line. The results show good agreement with theory.     

Elastic-scattering cross-section for electrons and positrons from atomic hydrogen

The differential cross-sections of atomic hydrogen for elastic scattering of electrons and positrons have been rederived with the help of a method using a single parameter-dependent unitary shift operator for the calculation of the direct contribution. When the parameter approaches zerc the new method leads to the well-known conventional Glauber results. The numerical calculations include polarization effects and the exchange corrections obtained according to alternative approximation methods. Results calculated with Franco’s exchange show a definite improvement over the earlier results for medium energy electrons at large angles of scattering. Total elastic cross-sections have been calculated for 50 and 100eV electrons and positrons.