TY - JOUR
T1 - Different natures of surface electronic transitions of carbon nanoparticles
AU - Sciortino, Alice
AU - Cannas, Marco
AU - Gelardi, Franco Mario
AU - Messina, Fabrizio
AU - Sciortino, null
AU - Valcárcel, null
AU - Soriano, null
AU - Cayuela, null
PY - 2017
Y1 - 2017
N2 - The photoluminescence behaviour of carbon-based nanodots is still debated. Both core and surface structures are involved in the emission mechanism, and the electronic transitions can be modified by external agents such as metal ions or pH, but the general relation between the structure and the optical function is poorly understood. Here, we report a comparative study on the effects of these variables, changing the core structure from crystalline to amorphous, and modifying the surface structure by different passivation procedures. Our results highlight that the emission mechanism of the tunable visible fluorescence is identical for crystalline and amorphous samples, indicating the independence of the emission from the core structure. Furthermore, surface functionalization weakly influences the emission peak position, but has large consequences on their interaction with different metal ions. This suggests the involvement of quasi-degenerate electronic states originating from the high density of different interacting groups on the surface. Finally, we report the presence of an unusual ultraviolet emission band for the amorphous sample, likely involving localized molecular-type chromophores with carboxyl ends. Our findings provide new information on the emission mechanisms of CDs and can be used to engineer sub-types of CDs displaying very similar emission features, but specifically tailored for different sensing applications.
AB - The photoluminescence behaviour of carbon-based nanodots is still debated. Both core and surface structures are involved in the emission mechanism, and the electronic transitions can be modified by external agents such as metal ions or pH, but the general relation between the structure and the optical function is poorly understood. Here, we report a comparative study on the effects of these variables, changing the core structure from crystalline to amorphous, and modifying the surface structure by different passivation procedures. Our results highlight that the emission mechanism of the tunable visible fluorescence is identical for crystalline and amorphous samples, indicating the independence of the emission from the core structure. Furthermore, surface functionalization weakly influences the emission peak position, but has large consequences on their interaction with different metal ions. This suggests the involvement of quasi-degenerate electronic states originating from the high density of different interacting groups on the surface. Finally, we report the presence of an unusual ultraviolet emission band for the amorphous sample, likely involving localized molecular-type chromophores with carboxyl ends. Our findings provide new information on the emission mechanisms of CDs and can be used to engineer sub-types of CDs displaying very similar emission features, but specifically tailored for different sensing applications.
KW - Physical and Theoretical Chemistry
KW - Physics and Astronomy (all)
KW - Physical and Theoretical Chemistry
KW - Physics and Astronomy (all)
UR - http://hdl.handle.net/10447/288448
UR - http://www.rsc.org/Publishing/Journals/CP/index.asp
M3 - Article
VL - 19
SP - 22670
EP - 22677
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
ER -