Electronic Excited States of Adsorbed Molecules

吸附分子的电子激发态

• 批准号: 09640704
• 负责人: MUNAKATA Toshiaki
• 金额: $ 2.05万
• 依托单位: The Institute of Physical and Chemical Research (RIKEN)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640704/
• 关键词: Two-photon photoemission; benzene; copper; surface electronic phenomena; adsorption; electronic excited state; desorption; フェムト秒レーザー; フェトム秒レーザー

When a molecule is adsorbed on a metal surface, new electronic states are formed in the vicinity of the Fermi level (E_F). Identification of the adsorption-induced electronic states, which act as frontier orbitals in chemical reactions at surfaces, is still an experimental challenge. Two-photon photoemission (2PPE) spectroscopy is used to probe normally unoccupied electronic states, but has a capability to probe the occupied and unoccupied states at the same time. Here a bonding electronic state induced by benzene adsorption on Cu (111) has been observed by means of 2PPE spectroscopy. The adsorption-induced bonding state is found at 0.3 eV blow E_F. Photoemission from the bonding state, which is weak in conventional one photon photoemission, is greatly enhanced by resonance with the image potential state. An angle resolved photoemission work for a benzene-adsorbed Cu (111) surface with photon energy of 5.45 eV has revealed that an adsorption-induced state due to hybridization of benzene pi^* and copper shows dispersion with electron momentum along the surface. The dispersion is well reproduced by a parabola with an effective electron mass ratio m^*/m_C=0.9. This suggests that the bonding state extends many copper lattice spacing from the adsorbed molecule. The bonding orbital is thought to be the origin of long range interactions of molecules on a metal surface.

当分子吸附在金属表面时，在费米能级（E_F）附近会形成新的电子态。吸附诱导的电子态，在表面的化学反应中作为前线轨道的识别，仍然是一个实验上的挑战。双光子光电发射（2 PPE）光谱用于探测通常未占据的电子态，但具有同时探测占据和未占据态的能力。本文用2 PPE谱观察到苯在Cu（111）表面吸附诱导的成键电子态。在E_F以下0.3eV处发现吸附诱导成键态。从键合态的光发射，这是在传统的单光子光发射弱，大大增强了与图像的潜在状态的共振。利用光子能量为5.45 eV的苯吸附Cu（111）表面的角分辨光电子能谱工作揭示了由于苯π ^* 和铜的杂化导致的吸附诱导态显示出电子动量沿着表面的色散。有效电子质量比m^*/m_C=0.9的抛物线很好地再现了色散。这表明键合状态从吸附的分子延伸了许多铜晶格间距。成键轨道被认为是金属表面上分子间长程相互作用的起源。

项目成果

T.Munakata, T.Sakashita, and K.Shudo: "Two-Photon Photoemission from Benzene Adsorbed on Cu(111)" J.Electron Spectrosc.Rel.Phenom.88-91. 591-595 (1998)

T.Munakata、T.Sakashita 和 K.Shudo：“Cu(111) 上吸附的苯的双光子光电发射”J.Electron Spectrosc.Rel.Phenom.88-91。

T.Munakata: "Two-photon photoemission from benzcne adsorbed on Cu(111)" J.Electron Spectrosc.Rel.Phenom.(印刷中).

T.Munakata：“吸附在 Cu(111) 上的苯的双光子光电子发射”J.Electron Spectrosc.Rel.Phenom.（出版中）。

T.Munakata: "Fine structure of the two-photon photoemission from benzene adsorbed on Cu(111)." Chem.Phys.Letters,. 271. 377-380 (1997)

T.Munakata：“吸附在 Cu(111) 上的苯的双光子光电子发射的精细结构。”

T.Munakata: "Fine structure of the two-photon photoemission from benzene adsorbed Cu(111)" Chemical Physics Letters. 271. 377-380 (1997)

T.Munakata：“苯吸附 Cu(111) 的双光子光电子发射的精细结构”化学物理快报。

T.Munakata: "Two-Photon photoemission from Benzene Adsorbed on Cu(111)." J.Electron Spectrosc.Rel.Phenom.,. 88-91. 591-595 (1998)

T.Munakata：“吸附在 Cu(111) 上的苯产生的双光子光电子发射。”