塞曼调制磁旋转激光光谱方法

首次在可见光波段采用塞曼调制磁旋转激光光谱技术有效地将磁旋转信号（ｎ＋，－ｎ－）从激光本底以及高阶磁旋转信号中分离出来，因而有非常高的测量灵敏度与信噪比以及无吸收本底，同时又可以抑制高转动量子态的跃迁谱线，减少谱线重叠现象，非常适合许多自由基分子的测量。文中给出了这种光谱技术的理论分析，并以ＮＯ２分子作为检验对象，由理论模拟计算所得谱线的强度，线型和位相与实测结果符合较好，因此也可利用这种光谱方法     

利用电晕放电实验研究NO分子γ电子带系发射光谱

基于NO分子的双重态能级结构特性,利用分子光谱理论分析和计算了NO分子γ带系(A2Σ+→X2Πr)的发射光谱,并通过电晕放电实验光谱进行验证。理论上计算了NO高低能级的双重电子态的能级分布,同时利用r质心近似法求取了能级间跃迁的电偶极矩函数,并得到了不同振动、转动能级间的爱因斯坦跃迁概率,然后计算出不同振动温度和转动温度条件下谱线的强度分布。最后进行NO和N2混合气体的电晕放电实验,通过将实验发射光谱同理论计算结果进行对比分析,确定了NO分子的振动温度和转动温度。     

高分辨高精密甲胺分子C—N伸缩带的兰姆凹陷饱和吸收红外光谱

甲胺分子(CH3NH2)是最简单的胺类分子,但由于分子中振动-转动-扭动-反转的相互作用使得其能级结构复杂和丰富密集且谱线强度差异很大的波谱,尤其是在频率中心位于1 044cm-1的C—N伸缩振动带。我们使用利用兰姆凹陷光谱技术自主研发的分辨率为0.4 MHz的二氧化碳激光和微波边带红外光谱仪将甲胺分子的C—N伸缩振动带的多普勒光谱中密集重合在一起的上百条谱线逐条分辨开和精密地测量了它们的跃迁频率。将它们标识归类和对J(J+1)作幂级数展开后,我们求得了27个系列的最初跃迁频率和它们的有效转动常数。     

用斯塔克光谱技术研究酞菁锡薄膜中的激子跃迁和电荷转移

采用斯塔克光谱技术研究了酞菁锡多晶薄膜中的激子跃迁和电荷转移。观察到一系列分子间电荷转移所形成的双分子激子谱带，显示了斯塔克光谱技术在探测淹没于弗伦克尔激子带下面的微弱电荷转移跃迁方面具有独特的优点和很高的灵敏度。     

钠分子B~1Π_u→X~1Σ_g~+LIF光谱及其强度研究

实验获得了Ar~+激光488nm线诱导Na_2分子产生B~1Π_u→X~1Σ~+_g跃迁荧光谱,其谱线的跃迁机制是分属于不同Q、P、R支系列的较高转动能级的B~1Π_u→X~1Σ~+_g电子态跃迁。研究了钠蒸气温度对Na_2分子激光诱导荧光光谱强度的变化关系,表明是由于荧光跃迁的上下能级不同弛豫过程的影响。分析了缓冲气体Ar对Na_a分子B~1Π_u态的碰撞猝灭作用,得出谱线强度与总气压的等轴双曲线关系,所得数据拟合曲线与实验很好地一致。     

Cl_2~+离子P支高激发振转态的跃迁谱线

基于描述双核分子体系包含转动光谱常数Lv所在高阶项在内的跃迁能谱的经典表达式,采用差分收敛法(DCM)的物理思想,推导获得了求解双核分子体系P支跃迁谱线的另一解析表达形式。对于某一双核分子体系的P支跃迁带,新的谱线表达式仅需要11条精确的实验跃迁谱线就可以正确预言高激发振转态的谱线结构,同时,利用谱线展开系数C还可以进一步给出计算谱线的不确定度以更可靠地预言高激发振转态的跃迁谱线。推导获得了相应的计算公式以正确获得对应跃迁带的转动光谱常数(B_(v′),B_(v″),D_(v′),D_(v″),H_(v′),H_(v″),L_(v′),L_(v″))。应用新的谱线表达式,对~(35) Cl_2~+和~(35) Cl ~(37) Cl~+离子电子态A~2Π_u-X~2Π_g(Ω=1/2)跃迁体系(3,7)跃迁带的P支跃迁谱线进行了详细研究,获得的计算结果不但能完全重复已知的实验数据,还获得了实验上未能获得的包含高激发振转态在内的跃迁谱线。另外,通过计算同时也得到了各跃迁带的高阶转动光谱常数。该研究方法和计算结果为人们进一步正确认识Cl_2~+离子电子态的内部能级结构及物理化学的相关性质提供了更完整的参考数据。     

NO2分子519～524 nm区的激光诱导荧光激发谱

实验测定了室温下NO2分子在519～524nm区域的高分辨激光诱导荧光激发谱,标识了25个振动带,并作了转动分析,确定了这些带的带源、转动常数以及旋-转偶合常数等分子常数,其中有8个振动带是新发现的,对振动带的转动结构分析表明,所有得到转动标识的谱线均属于平行跃迁2B2-2A1,其中上振动能级具有B2对称类是由于电子激发态2B2与电子基态的振动能级之间的强烈相互作用所致。     

费米共振对分子振动能级和光谱的影响

费米共振相互作用对多原子分子具有相同对称类的近简并振动能级及其光谱产生影响,利用定态微扰理论,分析了五阶近似下费米共振对三个振动能级的影响,应用于CO2分子的(0400),(1200)和(2000)三个近简并能级,计算结果与实验观测值符合较好,并讨论了费米共振对(0400),(1200)和(2000)向(0110)能级跃迁时光谱线强度的影响.     

精确预言双原子分子Q线系高振转激发态的跃迁谱线

用多重差分的方法,从双原子分子跃迁谱线的普遍表达式出发,已经建立起了预言双原子分子P线系高激发振转跃迁谱线的解析物理公式。采用同样的方法,充分利用现有实验条件下测定的部分振转跃迁谱线数据,文章建立了预言双原子分子Q线系高激发振转跃迁谱线的物理公式。使用该公式和一组经过物理筛选的(15条)精确的实验跃迁谱线,研究了IrN分子A1Π—X1Σ+跃迁系统中(4,1),(3,1)跃迁带的Q支发射光谱。结果表明,该公式不仅很好地重复了所有已知的实验光谱数据,且正确预言了实验没有获得的很多高转动量子态的未知发射谱线,从而提供了一种新的预言高转动量子态的未知跃迁谱线的物理方法。     

Ar-HCl转动跃迁光谱线压力加宽截面的理论计算

本文利用量子力学的Infinite Order Sudden Approximation近似方法和Ar-HCl H6(2)相互作用解析势模型,计算了HCl分子转动跃迁谱线被Ar展宽的压力加宽截面（相对能量范围30cm^-1—1000^-1)和平均弛豫截面（系统温度125K,175K,300K）.通过与密耦合方法（CC）计算值及实验值的比较,发现IOSA近似方法对转动能级较为稀疏的分子的j=0←j=1转动路迁谱线仍然可给出较好的计算结果,但要用于转动激发态跃迁谱线的计 关键词：     

Direct measurement of a pure rotation transition in H2(+)

The N = 1<--0 pure rotation transition in the nu = 19 level of the ground electronic state of H2(+) was observed at 14,961.7+/-1.1 MHz. Recent theory predicts significant electric dipole intensity in forbidden rotation and rotation-vibration transitions involving levels near the dissociation limit; the relevant levels are bound by only 0.74 and 0.22 cm(-1). The transition was predicted to have a transition moment of 0.42 D; our measurement is consistent with this value.     

B-factory signals for a warped extra dimension

We study predictions for B physics in a class of warped extra dimension models recently introduced, where few ( approximately 3) TeV Kaluza-Klein masses are consistent with electroweak data due to custodial symmetry. As in the standard model (SM), flavor violations arise due to the heavy top quark leading to striking signals: (i) New physics contributions to DeltaF=2 transitions are comparable to the SM, so the success of the SM unitarity triangle fit is a "coincidence." Thus, clean extractions of unitarity angles are likely to be affected, in addition to O(1) deviation from the SM prediction in B(s) mixing. (ii) O(1) deviation from various SM predictions for B-->X(s)l(+)l(-). (iii) Large mixing-induced CP asymmetry in radiative B decays. Also, the neutron electric dipole moment is roughly 20 times larger than the current bound so that this framework has a "CP problem."     

Spectra of the <Emphasis Type="Italic">gauche</Emphasis>-conformer of isopropyl alcohol in the millimeter and submillimeter wavelength regions

The spectrum of isopropyl alcohol in the millimeter region was recorded using a hybrid radio-spectrometer. A total of 1278 rotational and vibration-rotational transitions of its gauche-conformer were identified. Rotational constants and quartic centrifugal constants were refined. Sextic centrifugal constants and all six internal rotation constants were determined. The tunnel splitting parameter was refined. The reduced Hamiltonian of internal rotation is used for the first time in full format and describes sufficiently well the vibration-rotational spectrum of the gauche-conformer of isopropyl alcohol, which is complicated by internal rotation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 659–665, September–October, 2008.     

Pressure broadening mechanisms of the ammonia lines: Rotation,inversion and rotation-inversion spectra of NH3 perturbed by monoatomic gases

The half-widths of rotation, inversion and rotation-inversion spectral lines of NH₃ perturbed by rare gases have been calculated. These calculations take into account the R^-7 dispersion potential energy, which was previously studied by the present authors. A detailed analysis of the contribution of various induced collisional processes has shown that the ΔK = ±3 transitions induced by the dispersion potential are of importance for both the pure rotation spectrum and the inversion and rotation-inversion spectrum.     

Interaction of Wannier–Stark levels in a wide well superlattice

We have investigated the energy spectrum of a superlattice with wide quantum wells under the bias of an electric field perpendicular to the superlattice layers. By using photocurrent spectroscopy, transitions of Wannier–Stark levels for the various electron and hole states are observed, and at low fields, further structures corresponding to miniband edge transitions are found. Various anticrossings could be observed at higher and lower electric fields. The anticrossings at high electric fields are due to energy alignment of different electronic sublevels in adjacent wells. The anticrossing structures at low fields could be interpreted as resonances between intrawell and interwell excitonic Wannier–Stark states with equal sublevel states, where the anticrossing is caused by differences in exciton binding energy. Fitting of transitions and anticrossings was done by using a semi-empirical model and we have extracted relevant fitting parameters like the quantum-confined Stark coefficient, binding energies for the excitonic Wannier–Stark levels and the resonant coupling strength for states involved in the various anticrossing transitions. Finally, insight into the excitonic influences on the coupling of the WS states could be obtained by comparing the fitted parameters for the various transitions.     

Evidence for a contribution to the extrinsic photoconductive signal by hopping through excited states of the donors in silicon and CdTe

The intensities of the bound to bound transitions of the shallow donors in silicon and CdTe are found to be strongly electric field dependent when observed by photoconductivity techniques at low temperatures. Under these conditions significant differences can be detected between the photoconductive spectrum and the same transitions observed in absorption. The photoconductive peaks are shifted consistently to lower frequency compared with the absorption spectrum and additional peaks appear which are not significant features in absorption. These additional peaks are believed to result from the formation of molecular complexes of donors. The strong electric field dependence of the bound transitions observed in photoconductivity, the shift to lower frequency of the peaks and the enhancement of the additional lines can all be explained qualitatively on the assumption that the mechanism responsible for the generation of the photosignal involves hopping between the excited states of the molecular complexes     

Techniques to Treat the Continuum Applied to Electromagnetic Transitions in 8Be

Bremsstrahlung emission in collisions between charged nuclei is equivalent to nuclear gamma decay between continuum states. The way the continuum spectrum can be treated is not unique, and efficiency and accuracy of cross section calculations depend on the chosen method. In this work we describe, relate, and compare three different methods in practical calculations of inelastic cross sections, that is, by (i) treating the initial and final states as pure continuum states on the real energy axis, (ii) discretizing the continuum states on the real energy axis with a box boundary condition, and (iii) complex rotation of the hamiltonian (complex scaling method). The electric quadrupole transitions, 2⁺ → 0⁺ and 4⁺ → 2⁺, in α + α scattering are taken as an illustration.     

Optical transitions of holes in uniaxially compressed germanium

Spontaneous emission and photoconductivity of germanium with gallium impurity are studied for determining the energy spectrum of hole states in this material in which radiation can be induced as a result of transitions of holes between these states. Holes were excited by electric field pulses with a strength up to 12 kV/cm at T = 4.2 K under uniaxial compression of samples up to 12 kbar. It has been found that hole emission spectra for transitions between resonant and local states of the impurity have a structure identical to the photoconductivity and absorption spectra. Transitions from resonance states, which are associated with the heavy hole subband, have not been detected. It has been found that in an electric field lower than 100 V/cm, a compressed crystal emits as a result of transitions of heavy holes. In a strong electric field (1–3 kV/cm), emission is observed in the energy range up to 140 meV, and transitions with emission of TA and LO phonons appear in such a field. The emission spectra under pressures of 0 and 12 kbar differ insignificantly. Hence, it follows that the contributions from heavy and light holes in a strong electric field are indistinguishable.     

Optically biased photoreflectance spectroscopy of a GaAs epitaxial layer and an AlGaAs/GaAs quantum well

We propose optically biased photoreflectance (OBPR) spectroscopy, which is performed by continuous illumination of a secondary monochromatic light on a sample with conventional photoreflectance (PR), as a useful tool to investigate the internal electric fields dependence of the PR signals associated with band to band and quantum level transitions. Line shape of the PR signal has a strong dependence on the internal electric field. In OBPR, if a secondary incident light is absorbed, the internal electric field is suppressed by the photo-generated electron–hole pairs. On the other hand, if the secondary light is not absorbed, the internal electric field is not affected. Through the OBPR investigation of a GaAs epitaxial layer and an AlGaAs/GaAs quantum well, we are able to obtain an absorption like spectrum by performing a wavelength scan of a secondary monochromatic light. The results of OBPR measurements at each PR peak position show the contribution of the electric fields modification by the photo-generated carriers in each layers to the PR signals that are related to band gap and quantum level transitions.     

Linearly polarized terahertz radiation in uniaxially deformed Ge(Ga) upon the electric breakdown of an impurity

The polarization spectra of spontaneous terahertz radiation in uniaxially deformed germanium have been measured upon the electric breakdown of shallow acceptors. Lines with various degrees of polarization with respect to the compression axis have been observed in the radiation spectrum. These lines are associated with the optical transitions of holes between the excited and ground states of the acceptor, as well as with the transitions of holes from the valence band to the ground state of the impurity. At a pressure of about 3 ± 0.3 kbar in the [111] direction near the impurity breakdown, the linear polarization degree reaches ～80–90% in the main lines of terahertz radiation. As the electric field intensity increases, the depolarization of radiation is observed, which is caused by the heating of nonequilibrium holes by the electric field.