Dataset demonstrating the working-principles of surface-exposed nanoparticle sheet enhanced Raman spectroscopy (SENSERS) for solvent-free SERS

Abstract

Here, we present surface-enhanced Raman data for the calculation of signal uniformity and enhancement factor in SENSERS (surface-exposed nanoparticle sheet enhanced Raman spectroscopy). SEM was used to characterize the microstructure of the solid sample. The interaction between the solid sample and surface-exposed nanoparticle sheet was characterized using SERS and SEM. Based on these data a “skin” versus “sheet” type calculation method was used to calculate the magnitude of Raman signal enhancement within SENSERS. The data presented in this article is related to the research article entitled “Pressing Solids Directly Into Sheets of Plasmonic Nanojunctions Enables Solvent-Free Surface-Enhanced Raman Spectroscopy” (Xu et al., 2018).

Pressing solids directly into sheets of plasmonic nanojunctions enables solvent-free surface-enhanced Raman spectroscopy

“…Conversely, with analytes such as 4-mercaptobenzoic acid, which are known to spontaneously adsorb to Au or Ag nanoparticles through covalent bonding, the near maximum SERS signal was observed immediately the SENS was brought into contact with the solid sample even without any applied pressure (see Fig. 4 in ref [24]), in the same way as was reported in previous "stamping" experiments.…”

“…50 µm across x <1 µm deep; see METHODS SENSERS studies and Fig. 2 in ref [24] for details) and probed with a 60 µm diameter laser spot to average out local variations in the signal intensity. The thickness of the solid deposits depended on the amount of material deposited, so while drying 10 µL of 10 -4 M solutions created rings with detectable Raman signals 10 -5 M solutions did not (Fig 1c Raman).…”

“…2 pg of deposit in the 60 µm diameter probed laser spot (see Fig. 3 in ref [24] for calculations), sufficient material could be forced into the enhancing region to give a detectable SERS signal. The inset shows the calibration plot of the linear detection range of CV coffee ring obtained from drying 10 µL 5×10 -7 -5×10 -5 M solution (corresponding to ca.…”

“…To investigate the uniformity of hot-spots on the SENS substrate, we compared the SERS intensity of an adsorbed thiophenol monolayer between 10 random spots each on two separate SENS samples and obtained relative standard deviations of 11% and 5%, respectively (see Fig. 1 in ref [24]). This shows that the hot spot non-uniformity is not sufficient to account for the 10-19% variation observed for the pressed samples and therefore that a significant proportion of the signal variation observed in SENSERS spectra arises from the non-uniformity of the probed sample.…”

“…Figure 2c shows the relevant area at low magnification, where the part of the SENS that had contacted the bulk deposit shows clear damage and cratering but away from that area there has also been significant transfer of microcrystalline material during the pressing/peeling process. Some of the debris is in the form of "large" (5×5×5 µm 3 ) fragments but there are also smaller deposits, which appear as dark patches under normal incidence imaging (see Fig 6 in ref [24]) but with tilted viewing can be seen to be ca. 20-50 nm thick.…”