The electronic spectrum of Si3 I: triplet D(3h) system.
The electronic spectrum of Si3 I: triplet D(3h) system.
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Si3 I：三线态D(3h)体系的电子能谱。
DOI：
10.1063/1.4704672
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Michael C. McCarthy
中科院分区：
文献类型：
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作者：
N. Reilly;D. Kokkin;Xiujuan Zhuang;V. Gupta;Ramya Nagarajan;R. Fortenberry;John P. Maier;T. Steimle;John F. Stanton;Michael C. McCarthy
我们报告的测量喷射冷却的电子光谱的硅三聚体。在氩气中，用硅烷脉冲放电产生了Si（3），在18000 - 20800 cm（-1）范围内检测了激发光谱。共振双色双光子电离（R2 C2 PI）飞行时间质谱、激光诱导荧光/色散荧光和运动方程耦合团簇计算的组合被用来确定所观察到的光谱是由D（3 h）异构体的1（3）A（1）”-<$（3）A（2）“跃迁主导的。该光谱在18，600 ± 4 cm（-1）处有一个原点跃迁，在对称伸缩中有一个短的进展，频率为445 cm（-1），与激发到1的预测垂直跃迁能量2.34 eV非常一致（3）A（1）”状态，其计算的对称伸缩频率为480 cm（-1）。此外，从序列带和分散荧光确定的505 cm（-1）基态振动频率与早期对最低D（3 h）态的零电子动能研究和理论一致。R2 C2 PI在相同的质量通道（m/z = 84）中，但在不同的放电条件下观察到一个较弱的，重叠的带系统，其级数为360 cm（-1），被认为是由于Si（3）的（更复杂的）单重态C（2 v）基态（（1）A（1））的跃迁。在三重态分散荧光光谱中发射到后一种状态的证据表明在激发的三重态和单重态流形中存在广泛的混合。展望进一步的单重态系统的光谱表征和直接测量的最低单重态和三重态之间的能量分离进行了讨论。
We report the measurement of a jet-cooled electronic spectrum of the silicon trimer. Si(3) was produced in a pulsed discharge of silane in argon, and the excitation spectrum examined in the 18 000-20 800 cm(-1) region. A combination of resonant two-color two-photon ionization (R2C2PI) time-of-flight mass spectroscopy, laser-induced fluorescence/dispersed fluorescence, and equation-of-motion coupled-cluster calculations have been used to establish that the observed spectrum is dominated by the 1(3)A(1)" - ã (3)A(2)' transition of the D(3h) isomer. The spectrum has an origin transition at 18,600 ± 4 cm(-1) and a short progression in the symmetric stretch with a frequency of ∼445 cm(-1), in good agreement with a predicted vertical transition energy of 2.34 eV for excitation to the 1(3)A(1)" state, which has a calculated symmetric stretching frequency of 480 cm(-1). In addition, a ∼505 cm(-1) ground state vibrational frequency determined from sequence bands and dispersed fluorescence is in agreement with an earlier zero-electron kinetic energy study of the lowest D(3h) state and with theory. A weaker, overlapping band system with a ∼360 cm(-1) progression, observed in the same mass channel (m/z = 84) by R2C2PI but under different discharge conditions, is thought to be due to transitions from the (more complicated) singlet C(2v) ground state ((1)A(1)) state of Si(3). Evidence of emission to this latter state in the triplet dispersed fluorescence spectra suggests extensive mixing in the excited triplet and singlet manifolds. Prospects for further spectroscopic characterization of the singlet system and direct measurement of the energy separation between the lowest singlet and triplet states are discussed.