Luminescence from metallic quantum wells in a scanning tunneling microscope

Area of Science:

• Surface Science
• Condensed Matter Physics
• Quantum Mechanics

Background:

• Scanning tunneling microscopy (STM) is a powerful tool for atomic-scale surface imaging and manipulation.
• Metallic quantum wells exhibit unique electronic properties due to quantum confinement effects.
• Light emission phenomena in nanostructures can provide insights into their electronic and optical properties.

Purpose of the Study:

• To investigate light emission from a sodium (Na) metallic quantum well system on a copper (Cu)(111) surface induced by scanning tunneling microscopy.
• To analyze the origins of the observed light emission by correlating optical spectra with tunneling spectroscopy data.
• To explore the potential of this light emission as a local probe for the electronic structure of quantum well systems.

Main Methods:

• Utilizing a scanning tunneling microscope (STM) to induce and probe light emission.
• Acquiring optical spectra of the emitted light.
• Performing tunneling spectroscopy to analyze the electronic states within the quantum well.

Main Results:

• Observed light emission from the Na/Cu(111) system when subjected to tunneling current.
• Identified two distinct components in the emission spectra.
• Attributed one emission component to interband transitions between quantum well states of the Na layer.
• Linked the second emission component to plasmon-mediated processes, similar to those seen in noble metals.

Conclusions:

• The tunneling current in STM can effectively induce light emission from metallic quantum wells.
• The observed emission originates from both quantum well interband transitions and plasmon-mediated effects.
• This light emission serves as a unique and localized method for probing the electronic structure of quantum well systems like Na/Cu(111).