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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.10238 |
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| _version_ | 1866918532871094272 |
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| author | Apponi, Alice Castellano, Orlando Paoloni, Daniele Convertino, Domenica Mishra, Neeraj Coletti, Camilla Mariani, Carlo Ruocco, Alessandro |
| author_facet | Apponi, Alice Castellano, Orlando Paoloni, Daniele Convertino, Domenica Mishra, Neeraj Coletti, Camilla Mariani, Carlo Ruocco, Alessandro |
| contents | A comprehensive spectroscopic characterisation of two highly hydrogenated monolayer graphene samples transferred onto nickel grids is reported. With X ray photoemission spectroscopy on the C 1s core-level, a 100$\%$ $sp^3$ profile was observed upon hydrogenation of a more $sp^3$-like initially defected graphene, while a flatter, more $sp^2$-arranged, graphene reached a 62$\%$ $sp^3$ saturation. Low-energy reflection electron energy-loss spectroscopy (EELS) corroborates these findings through the $π$-plasmon excitation quenching for the fully $sp^3$ sample and a significant reduction for the partially converted one. The extreme surface sensitivity of low-energy reflection EELS enables extraction of the optical band gap of the hydrogenated layer even on a metallic support, yielding values of 6.3 and 6.2 eV for the two samples. The C--H stretching vibrational mode is also resolved, providing a direct fingerprint of graphene--hydrogen bonding. Finally, valence-band measurements of the $62\%$ saturated sample suggest the coexistence of one-sided and two-sided hydrogenation morphologies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_10238 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Wide Optical-Gap in Fully $sp^3$-Like Hydrogenated Monolayer Graphene Apponi, Alice Castellano, Orlando Paoloni, Daniele Convertino, Domenica Mishra, Neeraj Coletti, Camilla Mariani, Carlo Ruocco, Alessandro Materials Science A comprehensive spectroscopic characterisation of two highly hydrogenated monolayer graphene samples transferred onto nickel grids is reported. With X ray photoemission spectroscopy on the C 1s core-level, a 100$\%$ $sp^3$ profile was observed upon hydrogenation of a more $sp^3$-like initially defected graphene, while a flatter, more $sp^2$-arranged, graphene reached a 62$\%$ $sp^3$ saturation. Low-energy reflection electron energy-loss spectroscopy (EELS) corroborates these findings through the $π$-plasmon excitation quenching for the fully $sp^3$ sample and a significant reduction for the partially converted one. The extreme surface sensitivity of low-energy reflection EELS enables extraction of the optical band gap of the hydrogenated layer even on a metallic support, yielding values of 6.3 and 6.2 eV for the two samples. The C--H stretching vibrational mode is also resolved, providing a direct fingerprint of graphene--hydrogen bonding. Finally, valence-band measurements of the $62\%$ saturated sample suggest the coexistence of one-sided and two-sided hydrogenation morphologies. |
| title | A Wide Optical-Gap in Fully $sp^3$-Like Hydrogenated Monolayer Graphene |
| topic | Materials Science |
| url | https://arxiv.org/abs/2504.10238 |