Using Ambient Ion Beams to Write Nanostructured Patterns for Surface Enhanced Raman Spectroscopy

Abstract

Electrolytic spray deposition was used to pattern surfaces with 2D metallic nanostructures. Spots that contain silver nanoparticles (AgNP) were created by landing solvated silver ions at desired locations using electrically floated masks to focus the metal ions to an area as little as 20 μm in diameter. The AgNPs formed are unprotected and their aggregates can be used for surface-enhanced Raman spectroscopy (SERS). The morphology and SERS activity of the NP structures were controlled by the surface coverage of landed silver ions. The NP structures created could be used as substrates onto which SERS samples were deposited or prepared directly on top of predeposited samples of interest. The evenly distributed hot spots in the micron-sized aggregates had an average SERS enhancement factor of 10(8) . The surfaces showed SERS activity when using lasers of different wavelengths (532, 633, and 785 nm) and were stable in air.

Soft‐ and reactive landing of ions onto surfaces: Concepts and applications

“…Furthermore, when soft landed onto reactive surfaces, Raman spectroscopy revealed increased product yields compared to those obtained from solution phase mixing of the reactants (Badu‐Tawiah et al, ). More recently, the same group has demonstrated the use of ambient ion beams to prepare Ag substrates for SERS applications (Li et al, ) and Au nanoparticles for use in heterogeneous catalysis (Li et al, ). These results indicate that ambient ion soft landing is a straightforward and powerful technique which may be utilized in the future to prepare surfaces patterned with ions of a specific polarity.…”

“…Some of the earliest work in this area involved soft landing of ionic metal species into inert gas matrices (e.g., Ar, Kr, Ne) for subsequent analysis with techniques such as optical absorption, fluorescence, and Raman spectroscopy (Harbich et al, ; Honea et al, ; Felix et al, ). In addition to delivering ionic clusters and nanoparticles to surfaces for spectroscopic analysis, soft landing has been employed to prepare substrates to enable SERS analysis of other adsorbed molecules such as dyes (Panagopoulou et al, ; Hoffmann & Verbeck , ; Li et al, ). In another work, Benson and co‐workers immobilized a single fluorescent particle on the surface of an optical fiber using ion soft landing in a linear Paul trap (Gregor et al, ).…”

Catalysis by clusters with precise numbers of atoms

“…Electrospray ionization is another technique for introducing clusters into the gas phase and concomitantly ionizing these species 63 . A solution of the cluster precursor passes through a small biased capillary and is electrosprayed into a carrier gas forming a molecular beam of ions through supersonic expansion 64 .…”

Reaction of chloroauric acid with histidine in microdroplets yields a catalytic Au–(His)2complex

“…[16][17][18][19][20][21][22] The ESI/ ESSI as the main setup to generate charged microdroplets is usually accompanied by special redox reactions, which have been used for some synthesis reaction and nanomaterials. 23,24 Microdroplets as microreactors combined with on-line MS have been used to capture and identify transient intermediates of organic reactions, and microdroplet chemistry has been broadly applied in the eld of bioanalytical detection. [25][26][27] Microdroplets show a strikingly different environment for reactions than that of the corresponding bulk phase.…”