Method and apparatus for performing scanning tunneling optical absorption spectroscopy

• US 5,198,667 A
• Filed: 12/20/1991
• Issued: 03/30/1993
• Est. Priority Date: 12/20/1991
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Glembocki, Orest J., Snow, Eric S.
• Primary Examiner(s): Berman, Jack I.
• Assistant Examiner(s): BEYER, JAMES
• Application Number:
  US07/811,378
• Time in Patent Office: 466 Days
• Field of Search: 250/306, 250/307, 250/423 F
• US Class Current: 850/1
• CPC Class Codes: G01Q 60/12 STS [Scanning Tunnelling Spectroscopy]
• CPC Class Codes: Y10S 977/861 Scanning tunneling probe
• CPC Class Codes: Y10S 977/868 with optical means

Abstract

An apparatus for performing scanning tunneling optical absorption spectroscopy includes a scanning tunneling microscope tip positioned at a tunneling distance over a surface portion of a sample to be analyzed, biasing apparatus for producing an electric potential between said scanning tunneling microscope tip and said surface portion sufficient to cause a tunneling current to flow between said scanning tunneling microscope tip and said surface portion, illumination apparatus for illuminating said surface portion with modulated monochromatic light, and a detector for detecting an AC component of the tunneling current resulting from the modulated monochromatic light.

Claims

1. An apparatus for performing scanning tunneling optical absorption spectroscopy, said apparatus comprising:

a scanning tunneling microscope tip positioned at a tunneling distance over a surface region of a sample to be analyzed;

bias means for producing an electric potential between said scanning microscope tip and said surface region sufficient to cause a tunneling current to flow between said scanning tunneling microscope tip and said surface region;

illumination means for illuminating said surface region with a modulated monochromatic light, said illumination means including;

a monochromatic light source for producing monochromatic light; and

light modulator means for producing said modulated monochromatic light by modulating said monochromatic light produced by said monochromatic light source, said light modulator means including a polarization modulator; and

means for detecting an AC component of said tunneling current resulting from said modulated monochromatic light and for measuring a polarization based absorption coefficient of said surface region based on said AC component.

2. A method of performing scanning tunneling optical spectroscopy, said method comprising the steps of:

positioning a scanning tunneling microscope tip at a tunneling distance over a surface region of a sample to be analyzed;

producing an electrical potential between said scanning tunneling microscope tip and said surface region sufficient to cause a tunneling current to flow between said scanning tunneling microscope tip and said surface region;

illuminating the surface region with modulated monochromatic light;

said illuminating step including the steps of;

producing monochromatic light; and

modulating said monochromatic light to form said modulated monochromatic light, said step of modulating said monochromatic light including the step of;

modulating the polarization of said monochromatic light; and

detecting an AC component of the tunneling current resulting from said modulated monochromatic light for measuring a polarization based absorption coefficient of said surface region.