Pichler Marin, Chen Hongmin, Stwalley William C
Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA.
J Chem Phys. 2004 Jul 22;121(4):1796-801. doi: 10.1063/1.1767071.
We have performed high precision photoassociation spectroscopy of ultracold cesium gas. Using trap-loss fluorescence detection and controlling the background cesium pressure we were able to photoassociate atoms into excited states of ultracold molecules with large detunings up to 56 cm(-1) below the Cs(6S(1/2)) + Cs(6P(1/2)) atomic asymptote. Vibrational progressions are assigned to 0(g)(-), 0(u)(+), and 1(g) long-range states. By fitting the spectral data to the LeRoy-Bernstein expression, the effective coefficients of the leading long-range interactions and the vibrational quantum number at dissociation are obtained. In addition we have observed spectral perturbations between states of the same symmetry belonging to different asymptotes (6P(1/2) and 6P(3/2)). The perturbations are manifested through irregular vibrational level spacings and are especially pronounced in the 0(u)(+) symmetry. Many observed rotational levels indicate d- and higher partial wave contributions to the photoassociation cross section in the presence of trapping laser light, while spectral regions with only weak features suggest nodes in the lower state wave functions corresponding to the two ground state atoms asymptote.
我们对超冷铯气进行了高精度光缔合光谱研究。通过阱损失荧光检测并控制背景铯气压，我们能够将原子光缔合到超冷分子的激发态，失谐量高达低于Cs(6S(1/2)) + Cs(6P(1/2))原子渐近线56 cm(-1)。振动序列被指定为0(g)(-)、0(u)(+)和1(g)长程态。通过将光谱数据拟合到勒罗伊 - 伯恩斯坦表达式，得到了主要长程相互作用的有效系数和解离时的振动量子数。此外，我们还观察到属于不同渐近线（6P(1/2)和6P(3/2)）且具有相同对称性的态之间的光谱微扰。这些微扰通过不规则的振动能级间距表现出来，在0(u)(+)对称性中尤为明显。许多观测到的转动能级表明，在存在俘获激光的情况下，d波及更高分波对光缔合截面有贡献，而只有微弱特征的光谱区域表明对应于两个基态原子渐近线的低态波函数存在节点。
