铯饱和吸收光谱随抽运光强度的变化

研究了铯饱和吸收光谱随抽运光强度变化的情况，特别是６^２Ｓ_１／２Ｆ＝４→６^２Ｐ_３／２Ｆ′＝５的谱线的变化行为．在线偏振光抽运、线偏振光检测的情况下，计入所有相关的Ｚｅｅｍａｎ子能级之间的跃迁，考虑光抽运与饱和效应的共同作用，运用Ｒｕｎｇｅ-Ｋｕｔａ法则求解粒子数方程，计算得出的饱和吸收谱与实验结果符合得较好．还给出了较直观的物理解释 关键词：     

铷D2线饱和吸收光谱的测量

采用由同一半导体激光器发出的2束(弱探测光和强泵浦光)相向传播的激光光束,通过铷池,消除多普勒背景后,观察Rb-D2线超精细能级跃迁的饱和吸收光谱,并观测改变铷池的池温、泵浦光和信号光的功率对饱和吸收光谱的影响.     

基于铯133原子D1线直接吸收光谱的多普勒展宽热力学温度测量

玻尔兹曼常量的定值致使温度测量逐步从协议温标向热力学温标过渡。为实现一种量子化的热力学温度测量传感方案,利用直接吸收光谱方法精密测量铯133原子D1(6S~(1/2)→6P~(1/2))跃迁吸收谱线,依据谱线多普勒展宽分量获得原子气体在该平衡态下的热力学温度。实验验证将外腔扫描激光器输出频率锁定于精密波长计,实现1000s稳定时长条件下10~(-9)量级的频率稳定度;通过振幅型声光调制器闭环控制实现优于1000∶1的测量信噪比;通过福格特线型拟合得到多普勒展宽半高全宽宽度。在室温条件下,初步结果显示温度测量误差为0.12%。由此验证了基于原子直接吸收光谱的多普勒展宽测温方法可用来实现芯片尺度、免标定的热力学温度测量。     

激光二极管相对于铯饱和吸收D2线的无调制扰动三次谐波锁频

将频率调制加在声光调制器上 ,用三次谐波探测法获得了铯原子D2 线的三阶微分饱和光谱。采用这种激光器无调制扰动方案结合三次谐波锁频技术 ,实现了 85 2nm的分布布拉格反射器半导体激光器相对于 6S1/2 F =4- 6P3 /2 F′ =5超精细跃线的频率锁定。由锁定后的频率误差信号估算 ,10s内激光频率起伏小于± 35 0kHz ,相对频率稳定度约 1× 10 -9。这种无调制扰动方案可以消除一般的饱和吸收稳频方法中由于直接对激光器进行频率调制而带来的额外频率噪声 ;三次谐波锁频技术的应用 ,还可有效地降低铯原子饱和吸收谱中剩余多普勒背景的影响     

饱和吸收光谱实验的教学定位与教学设计

饱和吸收光谱是冷原子物理研究领域的重要实验,是磁光阱等复杂前沿实验的技术基础,展现了量子力学原理、精密光谱技术、激光控制技术、数理实验思想等众多近代物理实验层级的教学要点.本文详细介绍了清华大学近代物理实验课程中,饱和吸收光谱实验的教学定位、教学设计思路和课堂实践情况,并展现了该实验在层进式教学、学生认知规律研究、学生...     

傅立叶变换激光腔内吸收光谱方法研究吸收谱线的强度与线形

在原有傅立叶变换激光腔内吸收光谱实验装置的基础上,利用信号差分方法减少了光强波动对实验干涉谱图的影响,改善了信噪比.通过对大气中氧气在760nm处的吸收谱线的绝对强度测量,验证了该方法的定量测量能力.在不同压力条件下对磷烷v=6伸缩局域模泛频吸收谱带进行了测量,获得了其谱线的自压力加宽和自压力线移参数.     

铷原子饱和吸收光谱与偏振光谱对780nm半导体激光器稳频的比较

将激光频率锁定于合适的参考频率,可以有效地抑制激光器的频率起伏。本文采用铷原子D2线超精细跃迁线的饱和吸收光谱和偏振光谱分别获得鉴频曲线,通过电子伺服系统将频率校正信号负反馈到780 nm光栅外腔反馈半导体激光器外腔的压电陶瓷上的方法对激光器进行稳频。介绍了两种方法的基本原理和实验方案。与激光器自由运转300s时激光器典型的频率起伏约6.6 MHz相比,采用饱和吸收光谱和偏振光谱进行稳频,运转300 s时激光器典型的残余频率起伏分别约为1.5 MHz和0.6 MHz。分析表明,饱和吸收光谱稳频采用了相敏检波技术,需要对激光器进行频率调制,带来了额外的频率噪声,而偏振光谱稳频则是一种完全无频率调制的稳频方案。     

127)I2在633nm波段的超精细强谱线及稳频半导体激光器

报道了观察到的碘分子（¹²⁷I₂）在633nm波段的5组超精细强谱线,并对每组谱线的频率间距及相应振转能级的跃迁强度作出了计算,结果和实验吻合得很好．利用计算结果,对这5组谱线对应的振转能带作出了甄别．由于这些新谱线比用于氦氖激光器稳频的R（127）11.5跃迁强几百倍,因此利用这些新谱线作为半导体激光稳频的参考谱线,得到了功率为3mW的激光输出,这种半导体激光可成为新型光频标． 关键词：     

铷原子饱和吸收光谱与偏振光谱对780nm半导体激光器稳频的比较

将激光频率锁定于合适的参考频率,可以有效地抑制激光器的频率起伏。本文采用铷原子D2线超精细跃迁线的饱和吸收光谱和偏振光谱分别获得鉴频曲线,通过电子伺服系统将频率校正信号负反馈到780 nm光栅外腔反馈半导体激光器外腔的压电陶瓷上的方法对激光器进行稳频。介绍了两种方法的基本原理和实验方案。与激光器自由运转300s时激光器典型的频率起伏约6.6 MHz相比,采用饱和吸收光谱和偏振光谱进行稳频,运转300 s时激光器典型的残余频率起伏分别约为1.5 MHz和0.6 MHz。分析表明,饱和吸收光谱稳频采用了相敏检波技术,需要对激光器进行频率调制,带来了额外的频率噪声,而偏振光谱稳频则是一种完全无频率调制的稳频方案。     

可调谐激光二极管吸收光谱系统信号分析及谱线畸变校正技术研究

利用可调谐激光二极管吸收光谱技术进行气体检测时,波长调制伴随的光强幅度调制,会使解调出的谐波谱线发生畸变.在傅里叶分析的基础上对可调谐激光二极管吸收光谱任意调制幅度的波长调制光谱信号进行了分析,给出了光强幅度调制引起吸收谱线畸变的理论解释.提出了在波长调制过程中进行旧步平抑幅度调制的方法来消除谱线畸变,设计了实验方案并...     

谐波探测在Cs原子饱和吸收光谱中的应用

使用低频波长调制和高次谐波探测来测量Cs原子D₂线6S_1/2(F=4)→6P_3/2(F’=3、4、5)跃迁的方法,对谐波信号的展宽特性和灵敏度进行了分析.结果显示,减小调制电压可以压窄线宽,提高分辨率;在一定范围内增大调制电压可以提高谐波信号强度,提高测量灵敏度;提高分辨率要以损失灵敏度为代价.提高谐波次数可以提高分辨率.高次谐波可以获得高的灵敏度和分辨率.     

Cs2分子的光解光谱

利用He-Cd激光器的441.6 nm线光解Cs2分子, 使Cs(n2L)(nL=7P, 6D)态得到布居, 在Cs密度1到9×1015 cm-3范围内测量原子荧光对分子荧光强度比, 得到碰撞转移率系数对解离率之比分别为2.9×10-17和7.4×10-18 cm3. 测定Cs nLJ对nLJ'荧光分支比, 得到72P, 62D态精细结构解离率之比分别为0.53和0.43. 从远翼激发得到的精细结构转移截面与从其他激发过程得到的截面结果相符, 给出了碰撞转移到6D态外(即Cs(6D)+Cs(6S)→Cs(6D)以外的态)的截面为1.9×10-14 cm2.     

Absorption Spectra of Pyrene Aggregates in Saturated Solutions

The longwave part of the absorption spectra of saturated pyrene solutions in a number of organic solvents is measured. The interpretation of the longwave trail in these spectra as a band of aggregative nature with a complex mechanism of its formation is proposed.     

饱和一元醇远红外光谱的测试及仿真研究

用衰减全反射傅里叶光谱仪(FTIR-ATR)在室温条件下测试了甲醇、乙醇、丙醇、异丙醇、丁醇及异丁醇六种饱和一元醇在30～300 cm-1波段的远红外透射光谱。通过分析这六种具有类似化学结构的一元醇的远红外透射光谱,发现它们在30～150 cm-1波段均有明显的吸收峰,但在150～300 cm-1波段吸收峰不明显; 羟基在一元醇中的质量百分比越高,相关一元醇的远红外光谱的平均透过率越低; 直链一元醇的光谱平均透过率高于支链状的同分异构体。采用密度泛函理论B3LYP/6-311G(d,p)基组对甲醇单体和多聚体进行结构优化和频率计算。计算显示,在30～150 cm-1波段甲醇单体分子没有出现吸收峰,但是甲醇的多聚体则出现明显的吸收峰,计算得到的多聚体吸收峰位置与实际测量的结果相符合。结果表明,甲醇在太赫兹波段吸收的来自于不同形式聚合体的集体振动,甲醇溶液以甲醇三聚体为主要的存在形式。本成果不仅为研究有机分子在太赫兹波段的频率响应提供了新的实验方法,而且对进一步利用FTIR-ATR研究其他有机分子具有借鉴意义。     

Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

The laser spectroscopy of alkali-metal vapor is widely used in a number of applications, such as the Faraday anomalous dispersion optical fil- ter （FADOF）, the active optical clock, and wavelength references.Is＇ The Cs electrodeless dis- charge vapor lamp has rich spectra, including 455 nm, 459 nm, 728 nm, 852 nm, 1359 nm, and 1470 nm. The 852 nm laser pumping atoms from 6S1/2 to 6P3/2 have been used in FADOF.The 1359nm wave- length transited from 7S1/2 to 6P1/2 of Cs atoms can be used in the field of active optical clocks. The concept of active optical clocks has been proposed since 2005. Due to its good performance in sta- bility, the active optical clock has been extensively in- vestigated theoretically and experimentally in recent years, such as the two-level active optical clock, and three-level active optical clock. When considering the performance of the active optical clock, we hope to reduce the second-order Doppler shift in thermal atomic beam and the light shift induced by the pump- ing laser. To solve this issue, our group has recently proposed a four-level active optical clock, such as K 1252.2nm, Cs 1469nm, Rb 1366.9nm and Rb 728 nm. Moreover, the Rb 728 nm four-level quantum system has potentially a better performance than three long wavelength ones of Rb.     

饱和一元酸类化合物的拉曼光谱研究

通过实验检测获得了甲酸、乙酸、丙酸、丁酸四种-元酸的拉曼光谱.应用密度泛函理论对四种酸分子进行了模拟计算,计算结果与实验拉曼光谱吻合度较高,分别对四种酸的特征振动峰进行了详细的分析和振动归属.研究结果表明,甲酸的拉曼光谱与其他三种酸差异较大;乙酸、丙酸和丁酸的拉曼光谱具有一定的相似性,但主强峰位置和次强峰的强度存在着明...     

Saturated absorption spectroscopy of buffer-gas-cooled Barium monofluoride molecules

We report an experimental investigation on the Doppler-free saturated absorption spectroscopy of buffer-gas-cooled Barium monofluoride (BaF) molecules in a 4 K cryogenic cell. The obtained spectra with a resolution of 19 MHz, much smaller than previously observed in absorption spectroscopy, clearly resolve the hyperfine transitions. Moreover, we use these high-resolution spectra to fit the hyperfine splittings of excited A(v = 0) state and find the hyperfine splitting of the laser-cooling-relevant A²Π_1/2(v = 0, J = 1/2,+) state is about 18 MHz, much higher than the previous theoretically predicted value. This provides important missing information for laser cooling of BaF molecules.     

Temperature dependence of the Cs colloids absorption bands

Temperature dependence of the absorption bands due to Cs colloidal particles has been measured for colloids of different radii in additively colored CsBr and CsI. Large reversible shifts in the peak positions of the colloid bands are detected when we measure them at temperatures ranging between RT and LNT. The results are discussed and a tentative explanation based on the thermal change of Cs metal dielectric constants is proposed.     

Excitation and Emission Spectra of Cs2NaLnCl6 Crystals Using Synchrotron Radiation

ABSTRACT

The visible emission and vacuum ultraviolet excitation spectra of the series Cs₂NaLnCl₆ (Ln = Y, Nd, Sm, Eu, Tb, Er, Yb) and Cs₂NaYCl₆:Ln³⁺ (Ln = Sm, Er) have been recorded using synchrotron radiation at room temperature, and in some cases at 10 K. The excitation spectra comprise features associated with charge transfer, excitation from the valence to conduction band, and impurity bands. No d–f emissions were observed for these Ln³⁺ ions, so that the emission bands comprise intraconfigurational 4f ^N –4f ^N transitions and impurity bands, whose natures are discussed. Theoretical simulations of the f–d absorption spectra have been included. The comparison with data from the synchrotron at Desy enables a comprehensive account of the ground (or vibrationally excited ground for Ln²⁺) states of the Ln³⁺ 4f ^N , Ln³⁺ 4f ^N?15d, and Ln²⁺ 4f ^N+1 configurations relative to the valence and conduction bands of Cs₂NaLnCl₆, for which the band gaps are between 6.6 and 8.1 eV.