Size and structure dependent ultrafast dynamics of plasmonic gold nanosphere heterostructures on poly (ethylene glycol) brushes
Graphical abstract
Size and structure dependency of ultrafast dynamics of gold heterostructures on poly (ethylene glycol) brushes were investigated by pump-probe spectroscopy.
Section snippets
Sample preparation
Silicon wafers <100> were purchased from Wafer World Inc. Glass slides were purchased from Isolab Inc. PEG (35.0 kg/mol, BioUltra) was purchased from Sigma-Aldrich. Chlorobenzene, chloroform and ethanol were purchased from Merck. Au NSs (20 nm, 40 nm and 60 nm in diameter) were purchased form Ted Pella Inc. Water was purified with a purification system.
We cleaned all substrates (silicon wafers and glass slides) in UV-ozone chamber (Bioforce, procleaner) for 20 min. We prepared two types of
Results and discussion
Heterostructures that consist of Au NSs of different sizes are fabricated by immobilization of pre-synthesized colloidal particles on substrates functionalized PEG brushes (Fig. 1). SiOx terminated silicon and glass substrates are functionalized by grafting of PEG molecules through the condensation reaction between the hydroxyl functionality of the polymer and silanol groups of the substrates.
The citrate-stabilized Au NSs of different sizes (60 nm, 40 nm, 20 nm) were then immobilized on the PEG
Conclusion
In this study, it was shown that plasmonic properties and ultrafast dynamics of gold nanospheres can be easily tune by changing size and structures. Increasing number of immobilization cycle change the characteristic behavior of gold nanospheres to behave like nanorods. This way gives us good opportunity to make changes easily on optical properties of gold nanospheres on poly(ethylene glycol) brushes. Further, increasing number of immobilization cycles affects the relaxation time of samples due
Notes
The authors declare no competing financial interest.
Acknowledgments
MSO acknowledges support from Scientific and Technological Research Council of Turkey (TUBITAK) career reintegration fellowship (2232) under grant no 114C151.
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