title: Large-scale high-quality 2D silica crystals: dip-drawing formation and decoration with gold nanorods and nanospheres for SERS analysis.
abstract: High-quality colloidal crystals (CCs) are important for use in photonic research and as templates for large-scale plasmonic SERS substrates. We investigated how variations in temperature, colloid concentration, and dip-drawing parameters (rate, incubation time, etc) affect the structure of 2D CCs formed by highly monodisperse silica nanoparticles (SiNPs) synthesized in an l-arginine solution and regrown by a modified Stöber method. The best quality 2D CCs were obtained with aqueous 12 wt% colloids at a temperature of 25 °C, an incubation time of 1 min, and a drawing rate of 50 mm min(-1). Assembling of gold nanorods (GNRs) on 2D CCs resulted in the formation of ring-like chains with a preferential tail-to-tail orientation along the hexagonal boundaries. To the best of our knowledge, this is the first time that such nanostructures have been prepared. Owing to the preferential tail-to-tail packing of GNRs, 2D SiNP CC + GNR substrates demonstrated an analytical SERS enhancement of about 8000, which was 10 to 15 times higher than that for self-assembled GNRs on a silicon wafer. In addition, the analytical SERS enhancement was almost 60 times lower after replacing the nanorods in 2D SiNP CC + GNR substrates with 25 nm gold nanospheres.
authors.affiliation: Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prospekt Entuziastov, Saratov 410049, Russia. Saratov State University, 83 Ulitsa Astrakhanskaya, Saratov 410012, Russia.
authors.forename: Vitaly A
authors.initials: VA
authors.lastname: Khanadeev
authors.forename: Boris N
authors.initials: BN
authors.lastname: Khlebtsov
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Klimova
authors.forename: Mikhail Yu
authors.initials: MY
authors.lastname: Tsvetkov
authors.forename: Victor N
authors.initials: VN
authors.lastname: Bagratashvili
authors.forename: Gleb B
authors.initials: GB
authors.lastname: Sukhorukov
authors.forename: Nikolai G
authors.initials: NG
authors.lastname: Khlebtsov