宽带腔增强吸收光谱技术应用于痕量气体探测及气溶胶消光系数测量

基于氙灯的非相干宽带腔增强吸收光谱系统, 并将其应用于痕量气体及气溶胶消光系数的测量. 该系统的探测灵敏度通过测量NO₂在520—560 nm波长范围内的吸收得到验证, 最小可探测灵敏度为1.8× 10^-7cm^-1 (1σ, 0.12 s积分时间, 50次平均), 对应的NO₂探测极限～33 nmol/mol. 结合标准气溶胶粒子发生系统, 测量了不同浓度的单分散硫酸铵气溶胶粒子在532 nm波长处的消光系数, 得到粒径为600 nm的硫酸铵气溶胶的消光截面为1.12× 10^-8cm², 与文献报道值1.167× 10^-8cm²相一致, 验证了气溶胶测量的可行性和准确性.     

中心波长2.33 μm附近CO和CH4分子的同时探测

 采用分布反馈式半导体激光器作为探测光源,结合程长为100 m的离散型多通吸收池,采用直接吸收光谱技术,对室温下中心波长2.33 μm附近各种低体积分数的CO及混合气体（CO,CHCH₄和N₂）的直接吸收光谱进行了测量。选择CO在4 288.289 8 cm^-1位置的吸收谱线和CH₄在4 287.650 15 cm^-1处的吸收谱线进行痕量探测,在40 698 Pa的总压力下,实验测得CO的探测极限为8.15×10^-6(信噪比约为216）,CH4的探测极限为18.48×10^-6(信噪比约为147）。     

C2H2 Overtones Near 12300 cm-1 Revisited with a Very Sensitive Cavity Ring-down Spectrometer

利用单模连续的钛宝石激光器, 构建了一台光腔衰荡光谱仪, 其可探测的最小吸收可达1.8×10^-10/cm. 该光谱仪被用来记录C₂H₂分子在12240～12350 cm^-1的泛频光谱. 与在同一波段测量的已报到的CRDS和激光腔内吸收光谱仪结果比较,本测量同时具有更好的灵敏度和精度. 由此,获得了乙炔分子在12290.12、12311.82和12350.61 cm^-1附近高泛频谱带更准确的振转参数     

10.6μm激光辐照下光学薄膜的微弱吸收测量

 建立了表面热透镜技术测量光学薄膜微弱吸收的实验装置，对10.6μm CO₂激光辐照下镀制在Ge基底上的不同厚度的单层ZnS，YbF₃薄膜，以及镀制在Ge基底上不同膜系的（YbF₃/ZnSe）多层分光膜的弱吸收进行了测量，并对实验结果作了分析和讨论。实验结果表明，利用本实验系统已测得的待测样品的最低吸收为2.87×10^-4，测量系统的灵敏度为10^-5。     

多光程吸收的频率调制光谱

采用可连续调谐的半导体二极管激光器作探测光源,将多光程吸收光谱技术、频率调制光谱技术和相敏检波技术相结合,建立了一套具有高检测灵敏度和分辨率的测量气态分子光谱和进行微量分析的研究装置并利用该装置研究了动态分压强为40Pa和120Pa时,H₂O分子在7462cm^-1和7473cm^-1附近的近红外吸收光谱,检测灵敏度远高于传统吸收光谱技术,为气态分子的光谱研究和微量分析提供了一种高灵敏度的光谱检测方法.     

基于双共振吸收光谱法的14CO2探测

快速且准确地定量探测¹⁴CO₂在许多领域都有着重要应用. 超灵敏的光腔衰荡光谱技术是一种极具潜力的光学探测方法,但其存在灵敏度不足和易受其他CO₂同位素/杂质分子干扰的问题. 本文提出利用阶梯型双共振光谱法将¹⁴CO₂从基态激发至中间能级后,再用光腔衰荡光谱法去探测. 双共振的吸收过程可以有效提高探测的选择性. 本文分析了双共振吸收光谱的定量探测能力,模拟结果显示双共振光谱探测是无多普勒的,可以减少其他分子的吸收干扰,有望实现亚ppt水平的¹⁴CO₂高选择性探测.     

重离子背散射——测量表面与近表面痕量元素的一种新方法

本文报道了用重离子背散射探测表面、近表面微量重元素的新方法。通过选择入射离子种类,使入射离子原子量M₁等于或略大于基体原子量M₂,利用弹性散射运动学实现自动排除探测系统的脉冲堆积现象。实验结果表明利用能量为3MeVSi离子背散射,测量基体Si中注As的灵敏度优于2×10¹²原子/cm²;对基体Si表面的杂质元素Au,探测灵敏度高达2.2×10⁹原子/cm²。     

高Tc超导薄膜约瑟夫逊结光探测研究

我们研制了具有约瑟夫逊效应的高Tc GdBa₂Cu₃O₇-薄膜双晶晶界结,对其交直流约瑟夫逊效应进行了观测,并用其进行光探测,用波长为0.6328μm的He-Ne激光器辐照双晶结结区,系统观测了双晶晶界结的光响应特性,得到的最好结果如下噪音等效功率NEP=1.9×10^-13W,归一化探测率D=53×109cmHz^1/2W^-1,响应率Rv=4.2×10⁷V/W,响应时间τ=4.35×10^-7s.     

薄膜型超导红外(光)探测器

在高Tc GdBaCuO超导薄膜上,采用光刻技术分别制成两种不同结构的辐射、热测量器件及2×4集成阵列式微桥器件红外(光)探测器.探测器芯片安装在STD-3型红外探测器杜瓦冷指上.用黑体及波长为0.6328μm的He-Ne激光器辐照器件,系统观测各种器件的特性,其中最好的结果:在10Hz时的噪音等效功率NEP(500,10,1)=3.6×10^-12 WH_z^1/2;探测率D^*(500,10,1)=1.6×10¹⁰ cmH_z^1/2W^-1;响应率R_v=8.2×103VW^-1.另外,多元串接微桥器件出现的多台阶式的特性,可望在红外探测计量及高频方面获得重要应用.     

5.33 μm处磁旋转吸收光谱NO分子探测研究

本文基于直流磁场的磁旋转吸收光谱技术探测研究一氧化氮分子的痕量. 使用5.33 μm连续波量子级联激光器作为探测光源，结合Chernin型光学多通池，在1875.81 cm^-1(²∏_3/2(3/2)，υ=1←0)波长处进行探测. 108 m吸收光程下，实现了1.15 ppbv的探测极限(1s，1σ). 当采样时间延长到15 s，探测极限可提高至0.43 ppbv.     

New trlfs laboratory at the CTU in Prague

Early in 2006, construction and equipment of a new TRLFS (Time-Resolved Laser-induced Fluorescence Spectroscopy) laboratory was accomplished at the Czech Technical University in Prague, Czech Republic. In this contribution, the system is described in detail, the results of the first measurements obtained in the new laboratory for a standard UO ₂ ²⁺ - SO ₄ ²⁻ system are presented, and the future research plans are outlined.     

Ru原子荧光及其寿命的测量

本文设计了一个荧光探测系统,采用了电热原子化激光共振激发的方法,可方便地对难熔金属的原子荧光寿命进行测量,从而确定原子能级的寿命,实验中测得Ru原子[4d⁶5s(⁶D)5p]⁷P₄⁰能级的寿命为70.4ns(±5％)。     

Allowance for the shell structure of the 42100 Mo and 46110 Pd nuclei in the synthesis of 84200 Po, 88210 Ra, and 92220 U

The effect of the shell structure of colliding nuclei in calculating the entrance channel on the ensuing evolution of the product system is investigated. The entrance channel is calculated under the assumption of the nose-to-nose orientation of colliding nuclei. The following three reactions involving nuclei that are deformed in the ground state are considered: ₄₂¹⁰⁰Mo + ₄₂¹⁰⁰Mo → ₈₄¹⁰⁰Po, ₄₂¹⁰⁰Mo + ₄₆¹⁰⁰Pd → ₈₈²¹⁰Ra, and ₄₆¹¹⁰Pd + ₄₆¹¹⁰Pd → ₉₂²²⁰U. The state of the system at the point of touching is determined by the results obtained by calculating the entrance reaction channel. The shape of the system is specified by three collective coordinates (deformation parameters). The evolution of collective coordinates of the system is described in terms of Langevin equations. The potential energy of the system of colliding nuclei is calculated with allowance for their shell structure. It is shown that allowance for individual features of interacting nuclei in the entrance channel of the fusion-fission reactions makes it possible to obtain, for the reactions being considered, cross sections for evaporation-residue formation that are closer to available experimental data than their liquid-drop counterparts.     

正弦平方势与带电粒子沟道效应的能带结构

在量子力学的框架内描述了带电粒子与晶体相互作用，利用正弦平方势把沟道粒子的Schr?dinger方程化为Mathieu方程，根据Bloch定理讨论了系统能量分布，并用摄动法求解了方程的低阶不稳定区及其禁带宽度，系统自动呈现出了能带结构，再现了粒子束同晶体相互作用的周期性特征.而这一点正是其他相互作用势不曾有的. 关键词： 沟道效应 能带结构 正弦平方势 摄动法     

极化激元系统时间演化的量子涨落特性和非经典统计行为

将极化激元系统约化成模型单模光子-TO声子有效相互作用系统， 在此基础上以解析形式讨论了系统的力学量、压缩态、量子涨落特性以及亚泊松分布等非经典效应的动力学演化行为.结果表明，光子场与极化波量子场彼此交换能量过程随时间演化呈振荡性质，光子场和声子场都可以演化成压缩态，其二阶压缩度随时间演化成复杂周期振荡特性，这种非经典特性是非线性相互作用的结果并且以k₁项和k₂项同时存在并相互关联为前提.而此时光子和声子统计分布随时间演化呈现介于超Poison分布和亚Poison分布之间复杂周期振荡的新结果，非线性作用k₁项和k₂项对这种非经典统计行为都有贡献. 关键词： 极化激元系统动力学演化 单模光场-TO声子有效模型哈密顿量 量子涨落与压缩态 亚泊松分布     

Detection of the incommensurate modulation of the hydrogen-bond double-minimum potential in the antiferroelectric phase of NH4HSeO4

An incommensurate antiferroelectric phase in the NH₄HSeO₄ crystal was found by ⁷⁷Se high-resolution NMR in the temperature range 250–262 K. An anomalous line-shape continuum limited by two-edge singularities is observed in this region and described by plane-wave modulation. A model where the asymmetry of proton occupation in the H-bond system is modulated along a certain direction is discussed. The incommensurate structure is metastable.     

A15N-1H dipolar CSA solid-state NMR study of polymorphous polyglycine (-CO-CD2-15NH-)n

The solid-state¹H MAS (magic-angle spinning),²H static,¹⁵N CP (cross polarization)-MAS and¹⁵N-¹H dipolar CSA (chemical shielding anisotropy) NMR (nuclear magnetic resonance) spectra of two different modifications of C_α-deuterated^l5N-polyglycine, namely PG I and PG II (-CO-CD₂-^l5NH-)_n are measured. The data from these spectra are compared to previous NMR, infrared, Raman and inelastic neutron scattering work. The deuteration of C_α eliminates the largest intramolecular¹H-¹H dipolar coupling. The effect of the remaining (N)H-(N)H interaction (～5 kHz) is not negligible compared to the¹⁵N-¹H coupling (about 10 kHz). Its effect on the dipolar CSA spectra, described as a two-spin system, is analyzed analytically and numerically and it is shown that those parts of the powder spectrum, which correspond to orientations with a strong dipolar¹⁵N-¹H interaction, can be described as an effective two-spin system, permitting the measurement of the strength of the¹⁵N-¹H dipolar interaction and the orientation of the dipolar vector with respect to the¹⁵N CSA frame. While in the PG II system the¹⁵N CSA tensor is collinear with the amide plane, in the PG I system the CSA tensor is tilted ca. 16° with respect to the (δ₁₁δ₂₂) CSA plane.     

Absolute quantum yields of Cr3+2E → 4A2 emission in solids

The absolute quantum yields of powders have been obtained. The correction factors involved in using this method are described. The room temperature yield of ruby, 0.63 (⁴T₂←⁴A₂ excitation), is in good agreement with the previously reported single crystal results. No change in ruby quantum yield accompanies temperature reduction to 80°K. The absolute quantum yields of dilute (1–2%) Cr³⁺ in NaMgAl (C₂O₄)₃?9H₂O powders are 0.27 at 80°K. A small but measurable concentration dependence is observed with this system. Evidence to support an intramolecular intersystem crossing efficiency of unity is presented.     

The kinetic limitation of anti-stokes luminescence of Er3+ and Yb3+ doped infrared upconversion materials

Infrared-to-visible wave-length conversion in the Yb³⁺−Er³⁺ doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the range of 900–1000 nm of an IR-photon is first absorbed by Yb³⁺ ion as a sensitizer attributed to the resonant energy transition in Er³⁺ ion from ⁴ I _3/2 → ⁴ S _15/2 and ¹ F _9/2 → ⁴ I _15/2, respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from ⁴ I _11/2 and ¹ I _13/2, cross-relaxation from ⁴ S _3/2 and ¹ F _9/2 are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics of this rare-earth system.