Size and shape dependent photoluminescence and excited state decay rates of diamondoids.
Size and shape dependent photoluminescence and excited state decay rates of diamondoids.
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DOI：
10.1039/c3cp54570a
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发表时间：
2014-01
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通讯作者：
R. Richter;D. Wolter;T. Zimmermann;L. Landt;A. Knecht;C. Heidrich;A. Merli;O. Dopfer;P. Reiss;A. Ehresmann;J. Petersen;J. Dahl;R. Carlson;C. Bostedt;T. Möller;R. Mitrić;T. Rander
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作者：
R. Richter;D. Wolter;T. Zimmermann;L. Landt;A. Knecht;C. Heidrich;A. Merli;O. Dopfer;P. Reiss;A. Ehresmann;J. Petersen;J. Dahl;R. Carlson;C. Bostedt;T. Möller;R. Mitrić;T. Rander
我们目前的光致发光光谱和激发态衰减率的一系列金刚石，这代表分子结构类似物的氢钝化大块金刚石。五种最小的金刚烷（金刚烷-五金刚烷）的特定异构体已被带入气相并用同步辐射照射。所有研究的化合物在紫外光谱区表现出固有的光致发光。发射光谱表现出明显的振动精细结构，使用量子化学计算进行分析。我们表明，金刚烷的第一激发态的几何弛豫，表现出里德伯字符，导致Td对称性的损失。金刚烷的发光归因于从离域的第一激发态到电子基态的不同振动模式的跃迁。类似的几何变化的激发态结构也已确定在其他调查金刚石。激发态的衰减率显示出明显的依赖于金刚石的大小，但独立于粒子的几何形状，进一步表明电子激发时的粒子对称性的损失。
We present photoluminescence spectra and excited state decay rates of a series of diamondoids, which represent molecular structural analogues to hydrogen-passivated bulk diamond. Specific isomers of the five smallest diamondoids (adamantane-pentamantane) have been brought into the gas phase and irradiated with synchrotron radiation. All investigated compounds show intrinsic photoluminescence in the ultraviolet spectral region. The emission spectra exhibit pronounced vibrational fine structure which is analyzed using quantum chemical calculations. We show that the geometrical relaxation of the first excited state of adamantane, exhibiting Rydberg character, leads to the loss of Td symmetry. The luminescence of adamantane is attributed to a transition from the delocalized first excited state into different vibrational modes of the electronic ground state. Similar geometrical changes of the excited state structure have also been identified in the other investigated diamondoids. The excited state decay rates show a clear dependence on the size of the diamondoid, but are independent of the particle geometry, further indicating a loss of particle symmetry upon electronic excitation.