Laser Power Threshold of Chemical Transformation on Highly Uniform Plasmonic and Catalytic Nanosurface

Abstract

Noble metallic nanosurface exhibits both plasmonic and catalytic functions. Surface-enhanced Raman scattering of para-aminothiophenol (p-ATP) was measured on a highly uniform two-dimensional silver nanoparticle array at different intensities of an excitation laser (532 nm) ranging from 4 to 4000 W/mm 2 . It was observed that p-ATP was chemically transformed to 4,4′-dimercaptoazobenzene (DMAB) with the laser intensities of ≥40 W/mm 2 during the Raman measurement. At 4 W/mm 2 , the Raman peaks of DMAB disappeared, which indicates that the laser intensity was insufficient for the chemical transformation although it was sufficient for the Raman measurement. The highly uniform silver nanoparticle array allowed quantitative analysis on the Raman peak intensity. The threshold of the chemical transformation from p-ATP to DMAB was estimated to be ∼18.8 W/mm 2 on the silver nanoparticle array whose enhancement factor is ∼10 4 .

Photochemical Reaction Using Aminobenzenethiol Single Molecular Junction

“…The laser intensity is 50 kW/mm 2 in the present study. The progression of photo dimerization reactions under the current photon flux is consistent with the previous study [22]. Here, the conductance of the junction does not change by irradiation of light.…”

“…To obtain the SERS with high S/N ratios, the laser intensity of 50 kW/mm 2 and integration time of 1 s are minimum condition. The previous study of ABT molecules on Au or Ag nano particles shows that the photo dimerization reactions proceeds when the laser intensity is large (> 40 W/mm 2 ) [22]. The laser intensity is 50 kW/mm 2 in the present study.…”

“…The dependences of laser intensity, electrochemical potential, and pH of the solution have been investigated. Takeyasu with the laser intensity of 40 W/mm 2 on a highly uniform two dimensional Ag nano particle arrays [22]. By controlling the distance between nano particles, the progression of the photochemical reaction should be controlled with a fixed laser intensity.…”

Electrospun nanofiber templated assembly of hybrid nanoparticles

“…5a, three obvious peaks at 391, 1078 and 1578 cm À1 could be assigned to the a 1 vibrational modes of 4-ATP, suggesting that the electromagnetic eld enhancement dominated the SERS enhancement. 30,31 Moreover, these characteristic SERS peaks from the Au sNPs-Au bNPs nanober membrane are more intense than those from the Au sNPs nanober membrane, which may be ascribed to the increased hot spots. Additionally, the size of the Au bNPs may also be responsible for the SERS enhancement.…”

Fundamentals and applications of SERS-based bioanalytical sensing

“…Several studies show the use of plasmonic nanostructures in biophysical research [19,20], biomedical imaging and sensing [21,22], medical diagnostics [23], and cancer therapy [24,25]. In addition, the research that explores the combination of plasmonics with chemistry, chemoplasmonics [26][27][28], is another rapidly growing field. Chemical modifications made on the surface of the plasmonic structure may impart chemical specificity as well as higher sensitivity for improved analytical capabilities in applications based on SERS [29], LSPR spectroscopy [30], or surface plasmon resonance (SPR) spectroscopy [31,32].…”