1 Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada.
2 Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
3 Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Electronic address: andrea.cannizzo@iap.unibe.ch.
4 Department of Chemistry and Biochemistry and the Centre for NanoScience Research, Concordia University, Montreal, QC H4B 1R6, Canada; Quebec Centre for Advanced Materials, Concordia University, Montreal, QC H4B 1R6, Canada. Electronic address: rafik.naccache@concordia.ca.

Carbon dots have garnered significant attention owing to their versatile and highly tunable optical properties; however, the origins and the underlying mechanism remains a subject of debate especially for dual fluorescent systems. Here, we have prepared carbon dots from glutathione and formamide precursors via a one-pot solvothermal synthesis. Steady state and dynamic techniques indicate that these dual fluorescent dots possess distinct emissive carbon-core and a molecular states, which are responsible for the blue and red optical signatures, respectively. To further glean information into the fluorescence mechanism, electrochemical analysis was used to measure the bandgaps of the two fluorescent states, while femtosecond transient absorption spectroscopy evidenced the two-state model based on the observed heterogeneity and bimodal spectral distribution. Our findings provide novel and fundamental insights on the optical properties of dual fluorescent dots, which can translate to more effective and targeted application development particularly in bioimaging, multiplexed sensing and photocatalysis.