The fluorescence quenching of rhodamine 6G (R6G) by graphene oxide (GO) is governed by complex intermolecular interactions, among which electron transfer plays a pivotal role. This study focuses on elucidating the ultrafast electron transfer mechanism through time-resolved absorption spectroscopy and kinetic modeling. By systematically varying GO concentrations from 0 to 200 μg/mL, we observed distinct changes in the transient decay dynamics of R6G, providing direct evidence for the involvement of charge transfer processes.
At low GO concentrations (0–60 μg/mL), the fluorescence decay of R6G was well described by a two-exponential model, with lifetimes of approximately 26 ps and 18 ps. These components likely correspond to fast non-radiative relaxation within the R6G molecule and moderate energy dissipation due to weak interactions with GO. However, as GO concentration increased beyond 60 μg/mL, the decay kinetics could no longer be fitted with two exponentials. A three-exponential model provided a significantly better fit, revealing a new ultrafast decay component with a lifetime of less than 15 ps—indicative of an accelerated deactivation pathway.
This newly resolved process is attributed to efficient electron transfer from the photoexcited R6G to the GO matrix. The presence of oxygen-containing functional groups—particularly carbonyl and carboxyl moieties—on GO’s surface creates favorable sites for electron acceptance. Upon excitation, R6G transitions to a higher-energy state, enabling rapid electron donation to GO, thereby suppressing radiative emission. This process is consistent with previous reports indicating that GO acts as an effective electron sink.
Moreover, the spectral evolution in transient absorption data supports this interpretation. The stimulated emission signal from R6G diminishes rapidly at high GO concentrations, while concurrent rise signals in the 550–650 nm range suggest population transfer to lower-energy states associated with GO. This shift in spectral features confirms the formation of a transient charge-separated state, a hallmark of electron transfer.
The dependence of the third decay component on GO concentration further underscores its origin in interfacial electron transfer. As more GO sheets are introduced, the probability of R6G molecules approaching these electron-accepting sites increases, leading to a higher rate of charge separation. This correlation between concentration and electron transfer efficiency highlights the importance of molecular proximity in such systems.
These findings advance our understanding of the fundamental mechanisms behind fluorescence quenching in dye–nanomaterial hybrids. They confirm that electron transfer is not merely a secondary effect but a dominant, ultrafast process responsible for the observed quenching behavior at high GO loadings.Smad4 Antibody manufacturer This insight has significant implications for the rational design of optoelectronic devices, biosensors, and photodynamic therapy agents where controlled charge transfer is essential.CHRDL1 Antibody Purity
In conclusion, the transition from bi- to tri-exponential decay kinetics provides compelling evidence for the activation of an electron transfer channel in R6G–GO systems.PMID:34919824 The ultrafast nature of this process, occurring within tens of picoseconds, establishes it as a key factor in determining the photophysical properties of these hybrid materials. Future work should explore the influence of GO functionalization and structural defects on electron transfer efficiency to further optimize performance in sensing and energy conversion applications.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com