【作者】 马杰；

【导师】 贾锁堂； 肖连团；

【作者基本信息】 山西大学 ， 原子与分子物理， 2009， 博士

【摘要】 在过去的十几年时间里,超冷分子光谱的研究内容从单纯的分子能级、势能曲线和分子常数测量,逐步扩展到高分辨分子光谱测量、基本物理常数测量、超冷碰撞及多体问题、高精度频标、量子计算等众多前沿问题,引起了人们的极大兴趣。由于超冷分子所具有的极低温度特性,几乎完全克服了多普勒效应的影响,实现了分子的高分辨光谱测量。在超冷分子光谱研究中,荧光光谱技术是一种理想的测量手段。然而,其缺点是探测灵敏度低,无法满足高精度测量的需要。本文针对荧光光谱灵敏度低的问题,分析了制约高灵敏探测的因素,提出了通过三维速度选择调制光谱技术和光子计数光谱技术应用于超冷分子光缔合荧光光谱测量的实验方案,获得了高灵敏的超冷铯分子光谱。本文的主要创新性工作概括如下:1.利用三维速度选择调制光谱技术,实现了超冷铯分子激发态振动光谱的高灵敏测量,将现有的俘获损耗光谱可探测范围扩大了20cm^-1,得到了更低振动能级的光谱数据:通过理论拟合,获得了激发态铯分子的长程系数C₃和势能曲线。2.通过优化参数进一步提高三维速度选择调制光谱技术的探测灵敏度,获得了高灵敏、高分辨的超冷铯分子长程激发态O_g^-态的振转光谱,观测到跃迁几率极低的低振动量子数（v=1）的转动光谱。3.利用光子计数技术获得了高灵敏的超冷激发态铯分子近阈值振动光谱,为研究近阈值区域的势能曲线提供了重要的光谱数据。4.系统地研究了超冷铯分子激发态振转光谱对光缔合激光强度的依赖关系,观察到饱和效应,并通过理论拟合获得了光缔合饱和强度;同时,发现了不同振转能级对应的饱和强度也不相同,并从理论上对其进行了定性地解释。5.利用超低频率的波长调制光谱技术,发展了一种新颖的绝对频率锁定技术,实现了将激光器频率长期稳定地锁定在原子-分子跃迁频率上,为超冷分子实验提供了重要的稳频技术支持。更多还原

【Abstract】 During the past decade, the study of ultracold molecular spectroscopy has gradually extended to the high-resolution measurement of the molecular spectroscopy, the measurement of the basic physical constants, ultracold collisions, multi-body problem, high-precision frequency standard, quantum computing and many other cutting-edge issues from the simple study of ultracold molecular level, potential energy curves and molecular constants, and has aroused the great interest. With a very low temperature of ultracold molecules, Doppler-effect has been almost overcomed. It is possible to directly achieve a high-resolution molecular spectroscopy. In the study of ultra-cold molecular spectroscopy, fluorescence spectroscopy technique is a reasonable method. However, its detection sensitivity is too low to unable to meet the needs of high-precision measurements. In the thesis, the new detection techniques, three-dimensional velocity-selected modulation spectroscopy and photon counting spectroscopy, have been first offered by analyzing the main reasons of the low sensitivity. And the high sensitive ultracold cesium molecular spectroscopy has been obtained.The main innovation of the work summarized as follows:1. By using the three-dimensional velocity-selected modulation spectroscopy technique, the ultra-cold excited state Cs₂ vibrational spectroscopy with a high sensitivity has been obtained. The detection range of the present trap-loss spectroscopy has been extended to detect with 20cm^-1, and the spectroscopy data of lower lying vibrational levels have been obtained. The excited state cesium molecular coefficients C₃ and long-range potential energy curves are calculated by fitting with a theoretical formula.2. By optimizing the parameters of experiment, more high sensitivity has been achieved. As a result, the high-resolution and high-sensitive Cs₂ rovibrational spectroscopy has been obtained. And the rotational spectrum of the low-vibration quantum number （v = 1） has been observed with a very low transition probability.3. By using the photon counting technique, a near-threshold photoassociation spectroscopy has been obtained with a high sensitivity, which provides the important spectroscopy data for studying the energy curves in the near-threshold region. 4. It is operated to systematically study the dependence of the ultra-cold Cs₂ excited state rovibrational spectroscopy on the intensity of a photoassociation laser. Saturation effect was observed in our experiment. And the saturation intensities were obtained by the theoretical fitting. The difference among the saturation intensities for different rotational progressions has been found.5. It has been demonstrated a robust method of directly stabilizing diode laser frequency to the cesium atom-molecular hyperfine transitions. The trap loss fluorescence spectroscopy was applied to yield the error signal based on modulating molecules with ultralow modulation frequency.更多还原