Upgrade of a variable temperature scanning tunneling microscope for nanometer-scale spectromicroscopy

Area of Science:

• Surface science
• Spectroscopy
• Nanotechnology

Background:

• Tip-enhanced spectroscopies (TERS, TEPL, STML) merge probe microscopy resolution with optical spectroscopy.
• Existing systems often lack capabilities for cryogenic, high-resolution spectromicroscopy.

Purpose of the Study:

• To upgrade an ultrahigh vacuum variable-temperature scanning probe microscope (UHV-VT-SPM) for cryogenic tip-enhanced spectromicroscopy.
• To demonstrate the system's capability for high-resolution chemical and vibrational analysis.

Main Methods:

• Integration of a portable focusing lens (NA=0.45) for simultaneous light collection/injection.
• Utilizing plasmonically active probes (Ag, Au tips) for enhanced optical signals.
• Performing experiments at cryogenic temperatures within an UHV environment.

Main Results:

• Successful acquisition of electroluminescence (EL), Raman, and TERS spectra.
• Observation of C60 vibrational levels on Ag(111) with ~2 nm lateral resolution.
• Detection of intense anti-Stokes signals from C60 due to tunable gap plasmon distribution.

Conclusions:

• The upgraded UHV-VT-SPM enables state-of-the-art spatial and spectral resolution for surface analysis.
• This system facilitates advanced studies in surface chemistry, catalysis, and molecular electronics.
• The design offers new possibilities for nanoscale spectroscopic investigations.