title: Controlling successive ionic layer absorption and reaction cycles to optimize silver nanoparticle-induced localized surface plasmon resonance effects on the paper strip.
abstract: This study investigates why a silver nanoparticle (SNP)-induced surface-enhanced Raman scattering (SERS) paper chip fabricated at low successive ionic layer absorption and reaction (SILAR) cycles leads to a high SERS enhancement factor (7×108) with an inferior nanostructure and without generating a hot spot effect. The multi-layered structure of SNPs on cellulose fibers, verified by magnified scanning electron microscopy (SEM) and analyzed by a computational simulation method, was hypothesized as the reason. The pattern of simulated local electric field distribution with respect to the number of SILAR cycles showed good agreement with the experimental Raman intensity, regardless of the wavelength of the excitation laser sources. The simulated enhancement factor at the 785-nm excitation laser source (2.8×109) was 2.5 times greater than the experimental enhancement factor (1.1×109). A 532-nm excitation laser source exhibited the highest maximum local electric field intensity (1.9×1011), particularly at the interparticle gap called a hot spot. The short wavelength led to a strong electric field intensity caused by strong electromagnetic coupling arising from the SNP-induced local surface plasmon resonance (LSPR) effects through high excitation energy. These findings suggest that our paper-based SILAR-fabricated SNP-induced LSPR model is valid for understanding SNP-induced LSPR effects.
authors.affiliation: Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea.
authors.forename: Jae-Chul
authors.initials: JC
authors.lastname: Lee
authors.affiliation: Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea.
authors.forename: Wansun
authors.initials: W
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea.
authors.forename: Hun-Kuk
authors.initials: HK
authors.lastname: Park
authors.affiliation: Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea. Electronic address: medchoi@khu.ac.kr.
authors.forename: Samjin
authors.initials: S
authors.lastname: Choi
keywords: LSPR; Paper substrate; SERS; SILAR technique; Silver nanoparticle