I Y P T官网中的物理课程资源应用探究

课程资源的开发与利用是实现科学教育改革重要的实施途径. I Y P T( 国际青年物理学家锦标赛)在被 引入中国后受到广泛关注, 但I Y P T的官网作为一个介绍I Y P T赛事并总结其成果的平台在国内鲜有人提及、 应用. 本文在总结I Y P T官网内容和特色的基础上, 试图借助I Y P T官网开发原始问题库、 非良构问题解答库和物理辩论 视频库, 从而构建了基于I Y P T官网中探究课程资源的应用模式, 最后给出一些建议     

Precise measurement of the line width of the photoassociation spectra of ultracold molecules by using a frequency shifter

We propose a technique to precisely measure the line width of the photoassociation spectra of the excited cesium molecule by using a frequency shifter to generate two laser beams with a precise frequency difference. A series of photoassociation (PA) spectra are recorded with two laser beam induced molecular lines, whose peak separation serves as an accurate frequency ruler to measure the line width of the PA spectra. The full width half maximum line width was studied as a function of PA laser intensity. The extrapolated value at zero laser intensity is (34.84 ± 0.22) MHz. By analyzing other broadening mechanisms, a value of (32.02 ± 0.70) MHz was deduced. It is shown that this scheme is inexpensive, simple, robust, and is promising for applications in a variety of other atomic species.     

基于IYPT的YPT评价模式以及培养学生创新思维的认识与探索

创新思维的培养历来是教育的重点和难点.本文从近年引入中国的IYPT的赛制出发,结合作者参加CUPT以及JSYPT相关工作经历,在梳理YPT评价模式、探讨其特点基础上对培养学生创新思维的实施进行了探索.并以2014年JSYPT决赛"磁制动"比赛分析为例探讨了YPT评价模式用于培养学生创新思维的实践策略.     

A direct frequency comb for two-photon transition spectroscopy in a cesium vapor

A phase-stabilized femtosecond frequency comb is used to measure high-resolution spectra of two-photon transition 62S1/2-62P1/2,3/2-82S1/2 in a cesium vapor.The broadband laser output from a femtosecond frequency comb is split into counter-propagating parts,shaped in an original way,and focused into a room-temperature cesium vapor.We obtain high-resolution two-photon spectroscopy by scanning the repetition rate of femtosecond frequency comb,and through absolute frequency measurements.     

最优化参数控制提高超冷铯分子振转光谱的信噪比

超冷原子光缔合光谱对于研究长程分子势能结构、分子常数和分子相关动力学过程具有重要意义.光缔合光谱的信噪比作为衡量探测技术的重要指标之一,直接影响光谱的分辨能力和探测灵敏度.利用调制荧光光谱技术获得了超冷长程铯分子超精细振转光谱.通过研究解调参数,即积分时间和灵敏度,发现解调参数对光谱信号的信噪比有重要影响,且依赖关系呈非线性.结合相关实验系统,实现了对光谱信噪比的最优化控制,为进一步研究超冷铯分子长程态振转能级结构奠定了重要的实验基础.     

High resolution photoassociation spectra of an ultracold Cs2 long-range 0u＋ （6S1/2 ＋ 6P1/2） state＊

In this paper, ultracold cesium molecules are formed through photoassociation technology, which is carried out in a magneto-optical trap. High resolution photoassociaion spectra with the rotational progressions up to J = 7 are obtained. Three rovibrational levels of the long-range 0＋ state of Cs2 below the （6S1/2 ＋ 6P1/2） dissociation limit are specifically investigated. By fitting their binding energy intervals to the non-rigid rotational model, the rotational constant of the long- range 0u＋ state is determined. A proportional dependence of the value of the rotational constant on the vibrational quantum number is demonstrated.     

N-doped peanut membrane carbon quantum dots as a " off-on" fluorescence probe determination of hydroquinoneEI北大核心CSCD

N-doped peanut membrane carbon quantum dots (N-CQDs) were prepared by one-step hydrothermal method using peanut membrane and urea as materials. On the basis of investigating the spectral characteristics of the N-CQDs, we found that KMnO4 could cause the fluorescence signal of the N-CQDs to "turn-off" in the B-R buffer system with pH 10. 38. Once hydroquinone was added, the fluorescence signal of the N-CQDs-KMnO4 system gradually recovered and the fluorescence signal "turned on". Based on this, a new "off-on" fluorescence probe method for the detection of hydroquinone-N-CQDs-KMnO4 system was developed. Under the optimized conditions, the recovered fluorescence of N-CQDs was linearly related with the hydroquinone concentration in the range of 0. 10-200 mmol / L, the linear equation was ΔF = 1. 6819c + 153. 84 (r = 0. 9992), with the detection limit of 30 μmol / L. The method has been successfully applied to the determination of hydroquinone in simulated samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

High sensitive detection of high-order partial wave scattering in photoassociation of ultralcold atoms

We report on the observation of enhanced high-order partial wave scattering from atom–atom interaction via changing the temperature of a magneto–optical trap in the process of photoassociation. The high-order scattering partial wave is directly manifested through the large signal amplitude of the rovibrational resonance levels of trap-loss spectroscopy from photoassociation.     

Precise measurement of the line width of the photoassociation spectra of ultracold molecules by a frequency shifter

We propose a technique to precisely measure the line width of the photoassociation spectra of the excited cesium molecule by using a frequency shifter to generate two laser beams with a precise frequency difference. A series of photoassociation spectra are recorded with two laser beams induced molecular lines, whose peak separation serves as an accurate frequency ruler to measure the line width of the photoassociation (PA) spectra. The full width half maximum line width was studied as a function of PA laser intensity. The extrapolated value at zero laser intensity is (34.84 ± 0.22) MHz. By analyzing other broadening mechanisms, a value of (32.02 ± 0.70) MHz was deduced. It is shown that this scheme is inexpensive, simple, robust, and is promising for applications in a variety of other atomic species.