Optimized recipe for sol-gel-based SERS substrates

Abstract

The aim of this study was to develop further surface‐enhanced Raman scattering (SERS) substrates appropriate for the in situ environmental determination of chemicals in sea‐water important for global environmental problems. By encapsulating silver colloids in a sol–gel‐derived xerogel, SERS‐active coatings were produced with the high mechanical and chemical stability required for underwater field measurements. A flow‐through system was used which simulates measurements under real flow conditions. Substrates were optimized regarding sensitivity to different analytes and long‐term stability by varying solvent type, pH and sol–gel precursors. The substrates were characterized by their SERS activity and calibration functions of the Langmuir isotherm type were found for a variety of aromatic hydrocarbons. Limits of detection as low as 9 ppb for phenylacetylene and 135 ppb for biphenyl were achieved. Detailed tests on long‐term stability in sea‐water yielded a substrate half‐life of 13 days, which resulted in a substrate lifetime of at least 5 weeks. Copyright © 2000 John Wiley & Sons, Ltd.

Fabrication of photo-patterned microstructures in an organic–inorganic hybrid material incorporating silver nanoparticles

“…A variety of metal nanoparticles such as Ag, Au, Cu and Pt have been incorporated. Ag-doped sol-gel derived silica is of interest for a range of applications, including photochromic glass [9], non-linear optics [10], antibacterial materials [11] and as a substrate for surface-enhanced Raman spectroscopy (SERS) in sensing applications [12,13]. In general, these materials have been synthesized by dissolution of a silver salt in a precursor sol prepared from tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS), followed by reduction of the silver ions to metallic silver by electrochemical reduction [14,15], thermal treatment in air [16,17] or H 2 [18], or irradiation with UV light [16] or gamma rays [19].…”

Monolithic DFB laser diodes emitting at 785 nm for in situ SER Spectroscopy

“…The edge filters are designed to reflect the light at 785 nm with > 99.99 % reflection and have a cut on wavelength at 810 nm with 50 % transmission. The focus of the laser beam lies on top of a SERS substrate which is fixed outside the optode in front of the quartz window (12). The backscattered light is collected by lens L4 and directed to the edge filters (10) to eliminate the laser light from the Raman signal.…”

“…SER spectra were measured of PAHs in artificial seawater using sol-gel-based substrates 12 . These SERS substrates are reversible and can be used for several measurements.…”

Hydroxylamine reduced silver colloid for naphthalene and phenanthrene detection using surface-enhanced Raman spectroscopy

“…Surface-enhanced Raman scattering (SERS) for the past fifteen years have been employed in the in situ detection of polyaromatic hydrocarbons in aqueous solution. Several studies with impressive results on the quantitative determination of PAHs using functionalized metal nanoparticles have been reported [18][19][20][21][22][23][24][25][26][27][28][29].…”

“…Because of its unique sensitivity and selectivity, it is being used as an effective characterization tool in several areas including environmental applications [16,17]. Under certain conditions, even femtogram detection levels have been reported for different chemical species [18][19][20]. Single molecule detection by SERS is no more myth in the present scientific community.…”