薄原子蒸汽膜的双光子光谱及Dicke窄化

薄原子蒸汽膜的单光子Dcike窄化吸收光谱可以拓展到双光子情形，以级联三能级系统为例,从理论上得到了亚多普勒结构的双光子吸收光谱，其线型表现出和单光子过程相似的与膜厚和探测光波长的比值(L/λ)相关的周期性.当L/λ=(2n+1)/2(膜厚为半波长的奇数倍)时，吸收谱线窄化现象明显.当L/λ=2n/2(膜厚为半波长的偶数倍)时，单光子情形的谱线窄化现象消失，而双光子情形的谱线仍表现为亚多普勒结构，尤其在异侧入射的情形下，可以获得极窄的双光子谱线结构. 这种结构来自原子与腔壁碰撞的消激发效应和双光子过程的抽运-探测机制的贡献. 关键词： 薄原子蒸汽膜 双光子光谱 Dicke窄化     

级联三能级原子薄蒸汽膜的色散特性

从理论上讨论了囚禁于两电介质间的级联三能级系统薄原子蒸汽膜的色散特性.由于腔中慢速原子及泵浦-探测机制的速度选择贡献,色散谱线表现为Dicke窄化的亚多普勒结构及明显的慢光效应,当泵浦光和探测光异侧入射时这种现象更为突出.两个叠加的色散线型,一个对应光学泵浦,另一个对应可能出现的电磁诱致透明.     

原子吸收光谱仪七种元素吸收谱图的研究

原子吸收光谱分析法具有许多优越性，但其线性范围较窄。各元素的线性浓度范围，国内外仪器厂及有关专著均未给出，这给我们的分析工作带来诸多不利。为此，作者对7种元素的原子吸收谱图进行了分析研究，分别找出了7种元素在4种仪器工作条件下的浓度线性区。对减少样品前处理过程中的盲目性以及提高分析数据的准确性具有重要意义。     

火焰原子吸收法测定牙膏中的锶

本文阐述了牙膏锶的测定方法，各种类型的牙膏成份较为复杂，宜采用标准加入法。获得满意的精密度，准确度。     

石墨炉原子吸收法测定水中的铊

本文介绍了用石墨炉原子吸收法测定水中铊,也研究了各种基体和原子化器对测定水中铊的效果。实验表明,热解涂层平台以及含有10μg/L钯溶液分别是较好的原子化器和基体改进剂。方法的灵敏度是0.68μg/L,相对标准偏差为1.5～2.7%,回收率为95～103%。     

原子吸收光谱法测定南瓜吸收镉的研究

利用原子吸收分光光度计对南瓜吸收重金属镉的特性进行了研究。结果表明,随着镉浓度的增加,南瓜对镉的吸收量增大;随着水培时间的延长,南瓜对镉的吸收量增加,水培8 h后吸收量基本趋于饱和;吸收高峰在水培后2 h时出现,而后随时间的延长而逐渐降低。酸性和碱性条件较中性条件下南瓜植株对镉的吸收量均有下降,在pH 3条件下吸收量最小,pH 7条件下吸收量最大。     

石墨炉原子吸收法直接测定啤酒中铝

采用高速枪弹射击猪单后肢软组织，观察伤后远离原发伤道的血管内皮细胞的形态学变化，为远达效应的血流扰动学说提供实验资料。动物伤后６ｈ解剖，大体见双肺下叶、左室后壁以及大脑的痛、腹侧面均有不同程度的血管破裂、出血，或毛细血管充血。光镜见猪主动脉弓内皮细胞有水肿，或脱落呈“鞋钵样”垂直悬吊在血管腔内；连续切片见内皮层有剥脱现象。     

石墨炉原子吸收法测定鱼中砷

本文讨论了应用热解石墨管测定鱼中砷含量的实验方法。选择HNO_3-H_2O_2试测进行前处理,于样品消解前加入镍为基体改进剂,使鱼中砷的加标回收率达97%,检出下限为4μg/kg。     

火焰原子吸收法测定饲料中钙

本文用火焰原子吸收光谱法测定饲料中钙,并对等测溶液的酸度和氧化镧的加入量进行了讨论,当待测溶液酸度不大于1.3%时,用氧化镧作释放剂,测定结果稳定,本方法简便,快捷,具有良好的精密度和准确度,RSD为0.70%,加标回收率为99.4%-100.3%.     

Selective reflection combined with Fabry--Perot effects from two-level atoms confined between two dielectric walls

The coefficient of selective reflection at oblique incidence from two-level atoms confined between two dielectric walls is calculated in this paper. It is found to be related to the transient behaviour of atoms after colliding with the wall and the distribution of the field inside the vapour corresponds to L / \lambda , with L the thickness of the film and \lambda the incident wavelength. We find that the sub-Doppler structure is manifest both for normal incidence and small angle oblique incidence. It is feasible to detect the real part of selective reflection in several cases that have not been achieved before.     

Absorptive reduction and width narrowing in Λ-type atoms confined between two dielectric walls

This paper investigates the absorptive reduction and the width narrowing of electromagnetically induced transparency （EIT） in a thin vapour film of A-type atoms confined between two dielectric walls whose thickness is comparable with the wavelength of the probe field. The absorptive lines of the weak probe field exhibit strong reductions and very narrow EIT dips, which mainly results from the velocity slow-down effects and transient behaviour of atoms in a confined system. It is also shown that the lines are modified by the strength of the coupling field and the ratio of L/λ, with L the film thickness and λthe wavelength of the probe field. A simple robust recipe for EIT in a thin medium is achievable in experiment.     

受限原子极化相干缀饰四波混频光谱

研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制.     

受限原子极化相干缀饰四波混频光谱

研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制.     

Layering of confined water between two graphene sheets and its liquid-liquid transition

Molecular dynamics(MD) simulations are performed to explore the layering structure and liquid–liquid transition of liquid water confined between two graphene sheets with a varied distance at different pressures. Both the size of nanoslit and pressure could cause the layering and liquid–liquid transition of the confined water. With increase of pressure and the nanoslit's size, the confined water could have a more obvious layering. In addition, the neighboring water molecules firstly form chain structure, then will transform into square structure, and finally become triangle with increase of pressure. These results throw light on layering and liquid–liquid transition of water confined between two graphene sheets.     

Measurement of optical absorption in dielectric reflectors

The absorption of optical coatings can be measured by the method described with an accuracy of 0.001%. The radiation absorbed by the optical coating causes a change in the temperature of the coating and the substrate. The temperature change is measured by means of a thin-film resistance thermometer deposited on the substrate. The method was tested for laser reflectors at 1060 nm with a laser as a light source.     

Coherence-enhanced entanglement between two atoms at high temperature

This paper studies the entanglement properties in a system of two dipole-dipole coupled two-level atoms resonantly interacting with a single-mode thermal field. The results show that, when the temperature of the cavity is high enough （corresponding to the large value of the mean photon number）, the entanglement is greatly enhanced due to the initial atomic coherence. These results are helpful for controlling the atomic entanglement by changing the initial parameters of the system.     

囚禁于巴基球内的钠原子里德堡特性

通过非线性变换和特殊设计结点的B样条函数方法研究计算了囚禁于巴基球内的钠原子的里德堡能级结构和振子强度.计算结果表明,巴基球等效势阱深度可以有选择的影响和改变里德堡原子的特性.