Surface-enhanced raman spectroscopy on ultrathin gold/graphene substrates near the percolation threshold

2021 ◽  
Author(s):  
D. E. Tatarkin ◽  
D. I. Yakubovsky ◽  
D. A. Komissar ◽  
Y. V. Stebunov ◽  
A. V. Arsenin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Percolation Threshold ◽  
Surface Enhanced Raman Spectroscopy ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

scholarly journals Revisiting semicontinuous silver films as surface-enhanced Raman spectroscopy substrates

2019 ◽  
Vol 10 ◽  
pp. 1048-1055 ◽  
Author(s):  
Malwina Liszewska ◽  
Bogusław Budner ◽  
Małgorzata Norek ◽  
Bartłomiej J Jankiewicz ◽  
Piotr Nyga
Keyword(s):  
Raman Spectroscopy ◽  
Percolation Threshold ◽  
Physical Vapor Deposition ◽  
Surface Enhanced Raman Spectroscopy ◽  
Silver Films ◽  
Analytical Technique ◽  
Detection And Identification ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
The Many

Surface-enhanced Raman spectroscopy (SERS) is a very promising analytical technique for the detection and identification of trace amounts of analytes. Among the many substrates used in SERS of great interest are nanostructures fabricated using physical methods, such as semicontinuous metal films obtained via electron beam physical vapor deposition. In these studies, we investigate the influence of morphology of semicontinuous silver films on their SERS properties. The morphologies studied ranged from isolated particles through percolated films to almost continuous films. We found that films below the percolation threshold (transition from dielectric-like to metal-like) made of isolated silver structures provided the largest SERS enhancement of 4-aminothiophenol (4-ATP) analyte signals. The substrate closest to the percolation threshold has the SERS signal about four times lower than the highest signal sample.

scholarly journals Surface-Enhanced Raman Spectroscopy on Hybrid Graphene/Gold Substrates near the Percolation Threshold

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 164 ◽  
Author(s):  
Dmitry E. Tatarkin ◽  
Dmitry I. Yakubovsky ◽  
Georgy A. Ermolaev ◽  
Yury V. Stebunov ◽  
Artem A. Voronov ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Percolation Threshold ◽  
Surface Enhanced Raman Spectroscopy ◽  
Effective Dielectric Constant ◽  
Gold Films ◽  
Maximum Enhancement ◽  
Sers Signal ◽  
Gold Substrates ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Graphene is a promising platform for surface-enhanced Raman spectroscopy (SERS)-active substrates, primarily due to the possibility of quenching photoluminescence and fluorescence. Here we study ultrathin gold films near the percolation threshold fabricated by electron-beam deposition on monolayer CVD graphene. The advantages of such hybrid graphene/gold substrates for surface-enhanced Raman spectroscopy are discussed in comparison with conventional substrates without the graphene layer. The percolation threshold is determined by independent measurements of the sheet resistance and effective dielectric constant by spectroscopic ellipsometry. The surface morphology of the ultrathin gold films is analyzed by the use of scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the thicknesses of the films in addition to the quartz-crystal mass-thickness sensor are also measured by AFM. We experimentally demonstrate that the maximum SERS signal is observed near and slightly below the percolation threshold. In this case, the region of maximum enhancement of the SERS signal can be determined using the figure of merit (FOM), which is the ratio of the real and imaginary parts of the effective dielectric permittivity of the films. SERS measurements on hybrid graphene/gold substrates with the dye Crystal Violet show an enhancement factor of ~105 and also demonstrate the ability of graphene to quench photoluminescence by an average of ~60%.

Bacterial detection and differentiation via direct volatile organic compound sensing with surface enhanced Raman spectroscopy

2017 ◽  
Author(s):  
Caitlin S. DeJong ◽  
David I. Wang ◽  
Aleksandr Polyakov ◽  
Anita Rogacs ◽  
Steven J. Simske ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bacterial Infections ◽  
Direct Detection ◽  
Point Of Care ◽  
Surface Enhanced Raman Spectroscopy ◽  
E Coli ◽  
Recent Emergence ◽  
Surface Enhanced ◽  
Volatile Organic ◽  
Surface Enhanced Raman

Through the direct detection of bacterial volatile organic compounds (VOCs), via surface enhanced Raman spectroscopy (SERS), we report here a reconfigurable assay for the identification and monitoring of bacteria. We demonstrate differentiation between highly clinically relevant organisms: <i>Escherichia coli</i>, <i>Enterobacter cloacae</i>, and <i>Serratia marcescens</i>. This is the first differentiation of bacteria via SERS of bacterial VOC signatures. The assay also detected as few as 10 CFU/ml of <i>E. coli</i> in under 12 hrs, and detected <i>E. coli</i> from whole human blood and human urine in 16 hrs at clinically relevant concentrations of 10<sup>3</sup> CFU/ml and 10<sup>4</sup> CFU/ml, respectively. In addition, the recent emergence of portable Raman spectrometers uniquely allows SERS to bring VOC detection to point-of-care settings for diagnosing bacterial infections.

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