| Project/Area Number |
09640704
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
機能・物性・材料
|
|---|
| Research Institution | The Institute of Physical and Chemical Research (RIKEN) |
|---|
Principal Investigator |
MUNAKATA Toshiaki RIKEN,Microwave Physics Laboratory, Senior Scientist, マイクロ波物理研究室, 先任研究員 (20150873)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Project Status |
Completed (Fiscal Year 1998)
|
| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,700,000 (Direct Cost: ¥2,700,000)
|
|---|
| Keywords | 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 |
|---|
| Research Abstract |
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.
|
