Laser-assisted Stark deceleration of CaF in its rovibronic ground (high-field-seeking) state

Abstract

A near-resonant, red-detuning laser-assisted Stark deceleration scheme is proposed to slow CaF in its high-fieldseeking rovibronic ground state. The assisting Gaussian laser beam can confine CaF molecules transversely owing to the optical Stark effect. Simulations suggest that the present scheme is superior to previous Stark decelerators. Under typical experimental conditions, when the assisting laser frequency is red-detuned to the molecular transition (λ ∼ 606.3 nm) by 5.0 GHz and the laser power is about 5.6 W, the proposed decelerator can achieve a total number at the order of 10 4 CaF molecules with a number density at the order of 10 8 cm −3 . The equivalent temperature of the obtained cold CaF molecules is 2.3 mK. Additionally, the desired assisting laser power can be as low as about 1.2 W if keeping the red-detuning value to be 1.0 GHz, which further suggests its experimental feasibility.

Simulation of hyperfine-rotational spectrum of electromagnetic dipole transition rotation of BrF molecules

“…原子和分子光谱学在许多方面有重要应用，如原子和分子结构研究 [1] 、精密 测量 [2,3] 、以及寻找电子电偶极矩(eEDM) [4][5][6] 、验证精细结构常数 [7][8] 可能随时间 的变化等相关应用 [9][10] ． 原子分子的超精细结构， 通常掩盖于 Doppler 背景之中， 只有采用冷却方法才能加以观测．传统的制冷手段为超声束膨胀技术，可以将样 品冷却至 1 K 量级．然而，该技术所获得的冷却温度不足够低、样品的吸收长度 短、样品浓度起伏较大．这些缺点使得其难以满足现代原子分子光谱学及其应用 的需求．近几十年来，现代冷原子和冷分子物理 [11][12][13][14][15][16][17][18] 的飞速发展，为原子分子的 超精细结构的精确研究提供了坚实的研究平台， 使得我们可以同时进行超高分辨 率、超高精度和超高灵敏度的光谱研究，赋予了原子和分子光谱学新的生命． 超精细光谱可揭示原子分子内的弱核相互作用， 与价格不菲的核物理方法相 比，通过原子分子光谱学获得核内信息更为经济．相较于分子冷却的深入研究， 冷分子光谱的研究还相对较少．另一方面，冷分子光谱学 [11,[13][14][15][16][17][18] 所获得的精确的 分子超精细结构，对于冷分子的诸如碰撞、操控、进一步冷却乃至最终实现分子 玻色-爱因斯坦凝聚(BEC)等也至关重要．这就是说，分子超精细结构的研究，也 将促进冷分子物理及其应用研究的发展． 碱金属双原子冷分子在实验和理论上都取得了许多研究成果 [19][20][21][22][23] ．然而，它 们的化学性质不稳定， 尽管采用外加电场可以在一定程度上抑制这种化学反应 [24] ， 但这仍影响碱金属冷分子的各种应用．卤素异核极性分子化学性质稳定，在冷分 子领域必然会有更广泛的应用，而且采用近共振红失谐激光辅助 Stark 减速 [25][26][27] 将等效温度降至 1 mK 量级． 在卤素双原子分子中， BrF 的研究最少． 最早由 Smith 等人 [28] 于 1950 年报道了微波区 J = 1←0 的超精细光谱，后来 Calder 等人 [29] 提高 了分子常数的精度．Nair 等人 [30] 进一步研究了 BrF 的振动基态内 J = 1←0 和 J = 2←1 跃迁的超精细光谱，并获得了分子电偶极矩和核电四极矩．此外，Clyne 等 人 [31] 使用激光感应荧光光谱技术观测并分析了 BrF 的 B 3 Π 0…”

Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state*

“…[11][12][13] Thus, the study of the hyperfine structures together with their Zeeman and Stark effects of halogen diatomic molecules are essential. It is worth noting that heteronuclear halogen diatomic molecules could be slowed by our proposed near-resonantlaser-assisted Stark deceleration scheme [14] to the equivalent temperature at the order of microkelvin.…”

Mixed-field effect at the hyperfine level of 127I79Br in its rovibronic ground state: Toward field manipulation of cold molecules

“…In addition, they would probably be Stark decelerated into the equivalent temperature of 1 mK by employing the near-reddetune laser assisted Stark deceleration scheme. [13][14][15] The manipulation of cold molecules via mixed magnetic and electric fields offers three degrees of freedom to tune, two magnitudes of the two fields, and the angle between them, and thus, the mixed field manipulation should be more powerful. The pure Zeeman or Stark effect of the IBr molecule at the hyperfine level has been studied previously.…”