title: Use of a sample translation technique to minimize adverse effects of laser irradiation in surface-enhanced Raman spectrometry.
abstract: Surface-enhanced Raman spectroscopy (SERS) has proven to be a very powerful tool in the analysis of a wide range of compounds. However, continuous irradiation of the laser beam over the SERS substrate can promote the gross decomposition of the sample analytes and significantly broaden and diminish the intensities of observed spectral bands. In addition, the incident radiation can promote thermal or photolytic fragmentation of analytes, thereby altering the observable bands and possibly leading to a misinterpretation of analytical data. Finally, chemical or morphological changes in the SERS substrate are possible. This work presents the use of a sample translation technique (STT) as a means to minimize these adverse effects. By spinning the sample rapidly, the effective residence time of analytes and substrate within the irradiated zone is dramatically decreased without reduction of spectral acquisition time or the density of analyte in the zone. The technique is studied by acquiring SERS spectra of Naproxen USP, riboflavin, folic acid, Rhodamine 6G, and 4-aminothiophenol using silver islands on glass and silver-poly(dimethylsiloxane) composite substrates under various spinning and stationary conditions. In all cases, spectra show improvements upon spinning at laser powers as low as 4.2 (+/- 0.1) mW. Specific differences in the appearance of the spectra and the potential use of STT for improved SERS qualitative and quantitative determinations are presented.
authors.affiliation: University of Tennessee-Knoxville, Department of Chemistry, 552 Buehler Hall, Knoxville, Tennessee 37996-1600, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: De Jesús
authors.forename: K S
authors.initials: KS
authors.lastname: Giesfeldt
authors.forename: M J
authors.initials: MJ
authors.lastname: Sepaniak
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry / Q000528:radiation effects; D016477:Artifacts; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D005492:Folic Acid / Q000737:chemistry / Q000528:radiation effects; D007834:Lasers; D009288:Naproxen / Q000737:chemistry / Q000528:radiation effects; D011786:Quality Control; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012235:Rhodamines / Q000737:chemistry / Q000528:radiation effects; D012256:Riboflavin / Q000737:chemistry / Q000528:radiation effects; D012399:Rotation; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013438:Sulfhydryl Compounds
chemical_list: D000814:Aniline Compounds; D012235:Rhodamines; D013438:Sulfhydryl Compounds; C026188:rhodamine 6G; D009288:Naproxen; C064316:4-aminothiophenol; D005492:Folic Acid; D012256:Riboflavin