Carbon structures comprising sp1 chains (e.g., polyynes or cumulenes) can be synthesized by exploiting on-surface chemistry and molecular self-assembly of organic precursors, opening to the use of the full experimental and theoretical surface-science toolbox for their characterization. In particular, polarized near-edge X-ray absorption fine structure (NEXAFS) can be used to determine molecular adsorption angles and is here also suggested as a probe to discriminate sp1/sp2 character in the structures. We present an ab initio study of the polarized NEXAFS spectrum of model and real sp1/sp2 materials. Calculations are performed within density functional theory with plane waves and pseudopotentials, and spectra are computed by core-excited C potentials. We evaluate the dichroism in the spectrum for ideal carbynes and highlight the main differences relative to typical sp2 systems. We then consider a mixed polymer alternating sp1 C4 units with sp2 biphenyl groups, recently synthesized on Au(111), as well as other linear structures and two-dimensional networks, pointing out a spectral line shape specifically due to the the presence of linear C chains. Our study suggests that the measurements of polarized NEXAFS spectra could be used to distinctly fingerprint the presence of sp1 hybridization in surface-grown C structures.
Fingerprints of sp1 Hybridized C in the near-edge X-ray absorption spectra of surface-grown materials / G. Fratesi, S. Achilli, N. Manini, G. Onida, A. Baby, A. Ravikumar, A. Ugolotti, G.P. Brivio, A. Milani, C.S. Casari. - In: MATERIALS. - ISSN 1996-1944. - 11:12(2018 Dec 15), pp. 2556.1-2556.16.
|Titolo:||Fingerprints of sp1 Hybridized C in the near-edge X-ray absorption spectra of surface-grown materials|
FRATESI, GUIDO (Primo) (Corresponding)
ACHILLI, SIMONA (Secondo)
|Parole Chiave:||C 1s absorption; Carbynes; Density functional theory; Near edge X-ray absorption spectroscopy; On-surface chemistry; Self-assembly; Materials Science (all)|
|Settore Scientifico Disciplinare:||Settore FIS/03 - Fisica della Materia|
Settore CHIM/02 - Chimica Fisica
|Data di pubblicazione:||15-dic-2018|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.3390/ma11122556|
|Appare nelle tipologie:||01 - Articolo su periodico|