Chang Ray-Yuan, Tsai Chin-Chun, Whang Thou-Jen, Cheng Chuen-Ping
Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan.
J Chem Phys. 2005 Dec 8;123(22):224303. doi: 10.1063/1.2137717.
The phenomenon of electronic orbital angular momentum L uncoupled from its internuclear axis has been observed in the sodium dimer using high-resolution cw optical-optical double-resonance spectroscopy. When L uncoupling occurs, the degeneracy of Lambda doubling is removed. In our experiment, the intermediate B (1)Pi(u) state of Na(2) is excited from the thermally populated ground X (1)Sigma(g) (+) state by a single-line Ar(+) laser. Then, a single-mode dye laser is used to probe the Rydberg states from the intermediate state. The signals are detected by monitoring the UV fluorescence from the triplet gerade states back to the a (3)Sigma(u) (+) state via collision energy transfer. Under our experimental resolution, the splitting of Lambda doubling in the 5 (1)Delta(g) state of Na(2) can be measured. A total of 136 rovibronic levels with ef parities have been assigned to the 5 (1)Delta(g) state. The Lambda-splitting constants deduced from these data are q(0)=0.376(90)x10(-4) cm(-1), q(v)=0.114(6)x10(-4) cm(-1), and mu=0.76(33)x10(-8) cm(-1). In general, the Lambda splitting of the Delta states is considerably smaller than that of the Pi states. However, the first-order splitting constants q(0) and q(v) reported here are larger than those in the B (1)Pi(u) state. This is due to the L uncoupling of the Rydberg states.
利用高分辨率连续波光光双共振光谱，在钠二聚体中观测到了电子轨道角动量(L)与其核间轴解耦的现象。当(L)解耦发生时，(\Lambda)双重简并被消除。在我们的实验中，钠分子的中间(B(1)\Pi_u)态由单线氩离子激光从热填充的基态(X(1)\Sigma_g^+)态激发。然后，用单模染料激光探测从中间态激发的里德堡态。通过监测三重态 gerade 态经碰撞能量转移回到(a(3)\Sigma_u^+)态的紫外荧光来检测信号。在我们的实验分辨率下，可以测量钠分子(5(1)\Delta_g)态中(\Lambda)双重分裂。总共 136 个具有偶宇称的振转电子能级被归属到(5(1)\Delta_g)态。从这些数据推导出的(\Lambda)分裂常数为(q(0)=0.376(90)\times10^{-4}\ cm^{-1})，(q(v)=0.114(6)\times10^{-4}\ cm^{-1})，以及(\mu=0.76(33)\times10^{-8}\ cm^{-1})。一般来说，(\Delta)态的(\Lambda)分裂比(\Pi)态的要小得多。然而，这里报道的一级分裂常数(q(0))和(q(v))比(B(1)\Pi_u)态中的要大。这是由于里德堡态的(L)解耦。
