On-surface synthesis and characterization of polyynic carbon chains

Area of Science:

• Materials Science
• Chemistry
• Physics

Background:

• Carbyne, an sp-hybridized linear carbon allotrope, is highly reactive and unstable, limiting its exploration compared to graphene.
• Previous research has faced challenges in synthesizing and characterizing carbyne due to its instability.

Purpose of the Study:

• To achieve on-surface synthesis of polyynic carbon chains.
• To characterize the structure and electronic properties of synthesized carbyne chains.
• To produce atomically precise polyynes for detailed investigation.

Main Methods:

• On-surface synthesis via demetallization of organometallic polyynes on Au(111).
• Bond-resolved atomic force microscopy (AFM) for structural analysis.
• Tip-induced dehalogenation and ring-opening of decachloroanthracene on NaCl/Au(111).
• Scanning tunneling spectroscopy (STS) for electronic property measurement.

Main Results:

• Synthesis of polyynic carbon chains up to ~60 alkyne units (120 carbon atoms).
• Unambiguous confirmation of polyynic structure (alternating triple and single bonds) using high-resolution AFM.
• Production of an atomically precise C14 polyyne.
• Measurement of a 5.8 eV band gap for C14, closely matching theoretical predictions (5.48 eV).

Conclusions:

• Successful on-surface synthesis of long and atomically precise polyynes.
• Demonstration of carbyne's potential for detailed structural and electronic characterization.
• Advancement in the study of sp-hybridized carbon allotropes, offering new possibilities for materials science.