Forming Rb(+) snowballs in the center of He nanodroplets.
Forming Rb(+) snowballs in the center of He nanodroplets.
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在 He 纳米液滴的中心形成 Rb( ) 雪球。
DOI：
10.1039/c0cp01283a
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
W. Ernst
中科院分区：
文献类型：
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作者：
M. Theisen;F. Lackner;W. Ernst
采用共振两步电离方案，对掺有Rb原子的氦纳米液滴进行了电离。在飞行时间质谱图中可以观察到Rb离子随后的浸入。虽然碱金属原子通常在电子激发时从氦纳米液滴的表面解吸，但处于激发态5(2)P(1/2)的Rb则不符合这一规则(Auböck等人，Phys。雷特牧师，2008年，第101,35301)。在我们的新实验中，Rb原子被选择性地激发到5(2)P(1/2)或5(2)P(3/2)态。从那里，它们被激光脉冲电离。电离产物的飞行时间质谱图表明，5(2)P(1/2)态的中间布居不仅使Rb单体的电离过程具有选择性，而且还产生了非常高的Rb(+)-He(N)络合物。已经监测到质量高达数千Amu的离子，这可以用单个Rb离子浸入He纳米液滴来解释，在那里最有可能在He纳米液滴的中心形成一个雪球。由于离子最稳定的位置在He纳米液滴的中心，我们的结果与理论符合得很好。
Helium nanodroplets doped with rubidium atoms are ionized by applying a resonant two-step ionization scheme. Subsequent immersion of rubidium ions is observed in time-of-flight mass spectra. While alkali-metal atoms usually desorb from the surface of a helium nanodroplet upon electronic excitation, rubidium in its excited 5(2)P(1/2) state provides an exception from this rule (Auböck et al., Phys. Rev. Lett., 2008, 101, 35301). In our new experiment, Rb atoms are selectively excited either to the 5(2)P(1/2) or to the 5(2)P(3/2) state. From there they are ionized by a laser pulse. Time-of-flight mass spectra of the ionization products reveal that the intermediate population of the 5(2)P(1/2) state does not only make the ionization process Rb-monomer selective, but also gives rise to a very high yield of Rb(+)-He(N) complexes. Ions with masses of up to several thousand amu have been monitored, which can be explained by an immersion of the single Rb ion into the He nanodroplet, where most likely a snowball is formed in the center of the He nanodroplet. As the most stable position for an ion is in the center of a He nanodroplet, our results agree well with theory.