Rb-He exciplex formation on helium nanodroplets
Rb-He exciplex formation on helium nanodroplets
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DOI：
10.1063/1.1410118
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发表时间：
2001-12-08
影响因子：
4.4
通讯作者：
Ernst, WE
中科院分区：
文献类型：
--
作者：
Brühl, FR;Trasca, RA;Ernst, WE
将铷原子沉积在氦纳米液滴上，测量并解释了5 P-2- 5S-2跃迁的光激发和发射光谱。在激光激发5 P-2（3/2）态后，观察到来自（RbHe）-He-* 激基复合物的荧光，而泵浦D-1（5 P-2（1/2）-5S-2）线仅产生来自自由铷原子的发射。该观察结果与Reho [J. Chem. Phys. 113，9694（2000）]关于从掺杂的氦纳米液滴表面提取碱-氦激基复合物的最新模型的预测一致。1（2）Pi（1/2）电位的He-n-He-Rb-* 轴上的高势垒沿着阻止（RbHe）-He-* 在激发态寿命内的解吸，而1（2）Pi（3/2）电位允许激基复合物提取。另一方面，激发光谱反映了HenRb络合物的激发态1（2）Pi（1/2）、1（2）Pi（3/2）和2（2）Sigma（1/2）的结构，其势面强烈依赖于液滴表面附近的碱金属-He相互作用动力学。对于重表面掺杂剂如Rb或Cs，液滴表面将在掺杂剂的振动激发时强烈扭曲。以1（2）Sigma（1/2）基态为例讨论了电势的一些后果。(C)2001年美国物理学会。
Rubidium atoms have been deposited on helium nanodroplets and optical excitation and emission spectra of the 5 P-2-5 S-2 transition have been measured and interpreted. After laser excitation of the 5 P-2(3/2) state, fluorescence from a (RbHe)-He-* exciplex is observed while pumping the D-1 (5 P-2(1/2)-5 S-2) line yields only emission from free rubidium atoms. This observation is in agreement with the predictions from a recent model by Reho [J. Chem. Phys. 113, 9694 (2000)] about the extraction of an alkali-helium exciplex from the doped helium nanodroplet surface. A high barrier along the He-n-He-Rb-* axis of the 1 (2)Pi (1/2) potential prevents desorption of (RbHe)-He-* within the excited state lifetime, whereas the 1 (2)Pi (3/2) potential permits the exciplex extraction. The excitation spectrum, on the other hand, reflects the structure of the excited states 1 (2)Pi (1/2), 1 (2)Pi (3/2), and 2 (2)Sigma (1/2) of the HenRb complex whose potential surfaces will depend strongly on the alkali-He interaction dynamics near the droplet surface. For a heavy surface dopant like Rb or Cs the droplet surface will be strongly distorted upon vibrational excitation of the dopant. Some of the consequences for the potentials are discussed for the example of the 1 (2)Sigma (1/2) ground state. (C) 2001 American Institute of Physics.