Adsorption Structures and Electronic Properties of 1,4-Phenylene Diisocyanide on the Au(111) Surface
The adsorption structures and electronic properties of 1,4-phenylene diisocyanide (PDI) on a Au(111) surface have been studied using temperature programmed desorption (TPD), two-photon photoemission (2PPE), and scanning tunneling microscopy (STM). As deposited at 95 K, PDI molecules form disordered islands and short one-dimensional chains on Au(111) terraces. The work function decreases with increasing PDI coverage, and an occupied electronic state appears at 0.88 eV below the Fermi level. Annealing to 300 K causes the PDI molecules to reorganize on the surface and form ordered, one-dimensional molecular chains that extend for many tens of nanometers across the Au(111) terraces. The repeating structure of the molecular chains is consistent with a recently proposed [-Au-PDI-]{sub n} structure in which PDI molecules lie parallel to the surface and are interconnected by Au adatoms released from the Au(111) surface. The formation of the molecular chains is accompanied by a large drop in the work function which we attribute to an increase in the number and magnitude of interfacial dipoles. The electronic structure of the molecular chains is also characterized by occupied and unoccupied states at -0.88 eV below and +3.32 eV above the Fermi level, respectively. The latter are most prominent after annealing a PDI/Au(111) surface to 300 K, indicating that they are associated with interfacial states of the one-dimensional molecular chains.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1033587
- Report Number(s):
- BNL-96646-2011-JA; R&D Project: CO-007; KC0301020; TRN: US201203%%18
- Journal Information:
- Journal of Physical Chemistry C, Vol. 115, Issue 43; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
ANNEALING
DESORPTION
DIPOLES
ELECTRONIC STRUCTURE
FERMI LEVEL
PHOTOEMISSION
SCANNING TUNNELING MICROSCOPY
WORK FUNCTIONS
Photoelectron spectroscopy
work function
lowest unoccupied molecular orbital (LUMO)
ordered adsorption structure
functional nanomaterials