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Excited state charge transfer promoted Raman enhancement of copper phthalocyanine by twisted bilayer graphenes.
- Source :
-
Carbon . Mar2022, Vol. 188, p305-314. 10p. - Publication Year :
- 2022
-
Abstract
- Few atom thick, twisted bilayer graphene (tBLG) possesses a rotation angle (θ) dependent van Hove singularity (vHs). Fine-tuning vHs serves a potential method to enhance charge transfer (CT) in surface enhanced Raman spectroscopy. This study shows that tBLG having a specific θ promotes as high as a 1.7 times enhancement of the Raman signals of copper phthalocyanine (CuPc) as compared to that caused by single layer graphene (SLG). The results of a combination of reflection imaging spectroscopy and widefield Raman provide spatial and spectral information about both tBLG with θ ranging from 10.9 to 13.7° and the corresponding vHs. Comparison of Raman spectra of CuPc in presence and absence of tBLG demonstrates that a significant enhancement of certain CuPc vibrational modes occurs when the underlying tBLG possesses a θ = 12.2°, showing as high as 6.8 and 1.7 times enhancements of certain vibrational mode as compared to those of CuPc on bare and SLG substrates, respectively. Theoretical calculations indicate that a match between the energies of vHs of tBLG with those of frontier orbitals of CuPc facilitates CT from the distant SLG to CuPc. [Display omitted] [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00086223
- Volume :
- 188
- Database :
- Academic Search Index
- Journal :
- Carbon
- Publication Type :
- Academic Journal
- Accession number :
- 154438030
- Full Text :
- https://doi.org/10.1016/j.carbon.2021.11.070