Conical electromagnetic radiation in the Kretschmann attenuated total reflections configuration

Area of Science:

• Condensed matter physics
• Optics
• Surface science

Background:

• Surface plasmons are collective electron oscillations on a metal surface.
• Their interaction with surface roughness can generate conical electromagnetic radiation.
• The Kretschmann configuration is a standard method for exciting surface plasmons.

Purpose of the Study:

• To measure the polarization of conical radiation from surface plasmon scattering.
• To investigate the scattering properties of surface plasmons.
• To explore the capabilities of a scanning plasmon optical microscope (SPOM) for imaging plasmon scattering.

Main Methods:

• Utilized the Kretschmann attenuated total reflection configuration.
• Measured the polarization of conical electromagnetic radiation.
• Employed a scanning tunneling microscope tip as a localized plasmon-scattering center.
• Used a scanning plasmon optical microscope (SPOM) to image scattering events.

Main Results:

• Conical radiation was found to be p-polarized in the plane of observation.
• Plasmons were observed to preferentially scatter in the forward direction.
• SPOM imaging revealed surface irregularities acting as scattering centers and interference patterns.

Conclusions:

• Surface roughness scattering of surface plasmons generates p-polarized conical radiation.
• Forward scattering is a dominant mode for plasmons interacting with roughness.
• SPOM shows promise for detecting localized surface plasmons and characterizing nanoscale surface features.