Optical detection of plasmonic and interband excitations in 1-nm-wide indium atomic wires

3 páginas, 3 figuras.-- et al.
Infrared spectroscopy is demonstrated to sensitively detect electronic excitations in 1-nm-wide wires made of indium. The polarization-dependent spectra measured at room temperature show a strong broadband plasmonic absorption feature in the direction parallel to the wires, while in the perpendicular direction the wires stay nearly transparent in the same spectral range. At 88 K the wires do not show this broadband absorption anymore, but instead, several interband-transition features arise for both polarizations, in agreement to the gap opening of the metal-to-insulator transition as known for this one-dimensional structure.
This work is a part of the joint project “Strategic International Cooperative Program” funded by DFG-Germany (Grant No. PU193/9) and JST-Japan, and Spanish MICINN (Grant No. FIS2007-66711-C02-02) and Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT).