In situ nonlinear optical spectroscopy of electron–phonon couplings at alkali‐doped C60/Ag(111) interfaces
In situ nonlinear optical spectroscopy of electron–phonon couplings at alkali‐doped C60/Ag(111) interfaces
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DOI：
10.1002/pssb.200983947
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Ernest Kakudji;C. Silien;Dan Lis;Francesca Cecchet;A. Nouri;P. Thiry;A. Peremans;Y. Caudano
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文献类型：
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作者：
Ernest Kakudji;C. Silien;Dan Lis;Francesca Cecchet;A. Nouri;P. Thiry;A. Peremans;Y. Caudano
我们利用双共振红外-可见和频产生光谱（DR-SFG）研究了超高真空（UHV）下吸附在Ag（111）单晶上的C60和K掺杂C60单分子膜的振动和电子性质。我们记录了五个可见光波长的界面SFG光谱。由于DR-SFG现象，我们在扫描可见光波长时观察到富勒烯的完全对称Ag（2）模式的SFG强度的强烈依赖性。Ag（2）模的SFG强度分别在488 nm和532 nm处最强。结果表明，在C_（60）/Ag（111）界面和饱和K/C_（60）/Ag（111）界面处存在电子-声子耦合。它们使我们能够确定耦合电子跃迁的能量，并将电子共振与C60的hu（HOMO）到t1g（LUMO +1）跃迁联系起来。
We use doubly resonant, infrared‐visible sum‐frequency generation spectroscopy (DR‐SFG) to probe vibrational and electronic properties of C60 and K‐doped C60 monolayers adsorbed on Ag(111) single crystal under ultra‐high vacuum (UHV). We recorded the interface SFG spectra for five visible wavelengths. We observe a strong dependence of the SFG intensity of the totally symmetric Ag(2) mode of the fullerene while scanning the visible wavelength, due to the DR‐SFG phenomenon. The SFG intensity of the Ag(2) mode is the strongest at 488 nm and at 532 nm for the pure and fully doped monolayers, respectively. These results demonstrate the occurrence of electron–phonon couplings at the C60/Ag(111) and saturated K/C60/Ag(111) interfaces. They enable us to determine the energy of the coupled electronic transition and to link the electronic resonance to the hu (HOMO) to t1g (LUMO + 1) transition of C60.