Application of the stabilization method to interacting resonances

The stabilization method is applied to the case of interacting resonances in the photo-dissociation of van der Waals clusters composed by a rare gas atom bound to a dihalogen molecule. The study of an illustrative two-dimensional model consisting in a T-shaped NeI₂ molecule shows the adequacy of the method whenever the projection of the stabilization wave functions on the assumed prepared initial state is accounted for. The agreement of the fragmentation cross-sections with some previous results using the effective resolvent method and accurate close-coupling calculations is excellent. The method reveals its utility as a complementary tool since allows, through the analysis of the stabilization wave function in terms of zero-order levels, a precise characterization of the resonant states involved. Received 5 April 2002 / Received in final form 24 May 2002 Published online 19 July 2002     

Picosecond time-resolved nonresonant ionization detected IR spectroscopy on 7-azaindole dimer

The picosecond time-resolved IR spectrum of the 7-azaindole dimer has been measured by picosecond time-resolved nonresonant ionization detected IR spectroscopy. This new time-resolved technique was developed by combining nonresonant ionization detected IR (NID-IR) spectroscopy with tunable picosecond IR and UV lasers. The time-resolved NID-IR spectrum from 2 600 cm^-1 to 3 800 cm^-1 shows a drastic change from 1.5 ps to 11 ps time evolution. A mode-specific vibrational redistribution has been suggested. Received 14 May 2002 / Received in final form 11 June 2002 Published online 13 September 2002     

Influence of the soliton in anharmonic molecular crystals with temperature on Mössbauer effect

The influence of a soliton on the properties of the M?ssbauer effect resulting from the gamma-active nuclei situated at lattice sites in quasi-one-dimensional anharmonically organic molecular chains, in which the active nuclei emit gamma-photons, has been theoretically studied by a quantum vibrational model. An expression for the gamma-radiated M?ssbauer transition probability as a function of the temperature and non-linear interaction has been obtained. Finally we give some new properties of this effect from numerical calculation in such a case, which present a way to experimentally confirm the soliton existence in molecular crystals. Received 9 April 1998 and Received in final form 11 December 1998     

水热法合成硒化锡纳米盘及其形成机理探讨

本制备方法以二氧化硒(SeO2)为硒源,以氯化亚锡(SnCl2·2H2O)为锡源,以水合肼(N2H4·H2O)为还原剂在180 ℃ 的条件下利用水热法合成了硒化锡纳米盘.产物分别用扫描电子显微镜(SEM)、X射线衍射仪(XRD)表征手段进行了表征,探索了硒化锡纳米盘的形成机理.通过一系列反应物中不同硒元素与锡元素的摩尔比的条件实验,讨论了其对反应所得产物的影响;另外,通过不同反应温度的条件实验,研究了反应体系温度对所得反应产物的影响,讨论了相关的规律.     

助熔剂法生长的PLZST单晶的缺陷研究

本文介绍了助熔剂缓慢降温自发成核法生长的稀土掺杂锆钛锡酸铅镧(PLZST)晶体中出现的几种缺陷：包裹体、开裂、位错、枝晶,分析了这些缺陷的形成机理并提出了减少和消除这些缺陷的一些措施。     

Effective resolvent applied to interacting resonances

The wave operator theory of quantum dynamics is applied to characterize coupled metastable states. The theory extends to quasi bound states methods which are standard for dealing with bound levels. It is shown that interacting resonances can be investigated by means of small-dimensional effective Hamiltonians containing all the significant information of intrinsic properties which drive the various dynamical processes taking place. The study of the vibrational predissociation of I₂Ne, mediated by intramolecular energy redistribution, illustrates the power of the method. In addition to its accuracy to determine spectroscopic profiles and survival probabilities, it results more efficient than usual energy or time-domain numerical calculations. Received 25 January 2001 and Received in final form 11 May 2001     

Crystal Structure of Three Isomorphous Compounds of 2,5-Dibromopyridine with Tetrahalometalate(II) Ions

Abstract  Three salts of 2,5-dibromopyridinium with metal halides, (C₅H₄Br₂N)₂[CuCl₄], (I); (C₅H₄Br₂N)₂[CuBr₄], (II); and (C₅H₄Br₂N)₂[CdBr₄], (III), are isomorphous in C2/c with cell volumes 1864.5(8), 1974.6(4) and 2072.9(7) ?³, respectively. For the Cu cases (I) and (II) the discrete [MX₄]²⁻ anions are strongly distorted with max/min tetrahedral angles of 131.19(8)°/99.67(9)° and 130.24(5)°/99.36(11)°, respectively. For the Cd case (III) the distortion is much less with max/min tetrahedral angles of 115.97(3)°/105.99(4)°. The cations are planar. The short hal···hal contacts are for (I), aryl Br···anionic Cl 3.335(3) ? and 3.430(2) ?; for (II), aryl Br···anionic Br 3.473(2) ? and 3.567(2) ?; and for (III), aryl Br···anionic Br 3.452(1) ? and 3.675(1) ?. Longer aryl Br···aryl Br contacts (3.842(2) ? to 3.967(2) ? are present in the three isomorphs. Bifurcated hydrogen bonding to two anionic halides exist in the three structures with N–H···Cl 3.365(8) ? and 3.379(7) ? in (I), N–H···Br 3.539(11) ? and 3.425(11) ? in (II), and N–H···Br 3.426(5) ? and 3.387(5) ? in (III). Short ring contacts exist with the perpendicular distances between mean cation planes in (I), (II), and (III) of 3.68(6) ?, 3.56(1) ? and 3.72(1) ?, respectively. Index Abstract  An analysis is made of the competition between hydrogen bonding, halogen–halogen and halogen–halide interactions as well as differences between [CuX₄]²⁻ and [CdX_4] ²⁻ polydedra in the structures of the three isomorphs.      

Nuclear quadrupole hyperfine quantum beats in HCl and pyrimidine measured by the pump-probe method using REMPI/LIF detection

Coherent time resolved IR-UV double resonance spectroscopy with REMPI and/or LIF detection has been used to measure the nuclear hyperfine structure of a diatomic and a polyatomic molecule. The pump-probe technique was applied and the experimental set up was optimized to achieve highest spectral resolution. Following excitation of the HCl fundamental vibrational transition by a nanosecond IR laser pulse, the nuclear quadrupole coupling constants were determined to be eQq = −69.51(22) MHz for H³⁵Cl and eQq = −54.40(16) MHz for H³⁷Cl in the J = 1 and J = 2 states of the υ = 1 level. Nuclear (Cl) spin-rotation interaction was shown to be active with the corresponding coupling constant being C _I = 0.068(10) MHz for H³⁵Cl and C _I = 0.049(8) MHz for H³⁷Cl. For pyrimidine a C-H stretch vibration ν ₁₃ was excited and the quadrupole tensor elements for the rovibronic states J _{K a} ,K _c = 1₁₀ and 1₀₁ of the υ ₁₃ = 1 level were found to be χ _aa = −3.095(10) MHz, χ _bb = 0.227(10) MHz and χ _cc = 3.322(10) MHz. In this case the residual frequency error was reduced to 8 kHz. The results of these jet experiments independently confirm those from millimeter wave and microwave measurements on static gas samples.     

ZnS/g-C3N4复合型催化剂的制备及其可见光光催化性能

利用共沉淀的方法制备了ZnS/g-C3N4复合型催化剂,并考察其在可见光区对罗丹明B的光降解性能的影响机制.采用TEM、BET、XRD、ICP、FT-IR和XPS等分析手段表征了样品,并评价了样品的光催化活性.结果表明,与g-C3N4相比,ZnS负载量为5wt;的ZnS/g-C3N4催化剂活性会更高一些,且经过四次循环实验后样品的光催化性能未明显失活.这可能归因于ZnS和g-C3N4所形成的异质结构提高了光催化效率.     

Position dependent mass Scarf Hamiltonians generated via the Riccati equation

The construction of position dependent mass Scarf Hamiltonians of the trigonometric as well as the hyperbolic types is addressed by means of the factorization method and the Riccati equation. These Hamiltonians are shown to be independent of the ordering parameter of the kinetic term. Additionally, new families of Hamiltonians with the Scarf spectrum are also determined by supersymmetry. Some examples for masses with and without singularities are considered to illustrate our results.