Monolayer Detection on Flat Metal Surface via Surface Enhanced Raman Spectroscopy and Sum Frequency Generation Spectroscopy

2012 ◽  
Vol 12 (1) ◽  
pp. 361-364 ◽  
Author(s):  
Dawei Li ◽  
Jiao Chen ◽  
Haibing He ◽  
Rongping Zhang ◽  
Wei Chen ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Metal Surface ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Sum Frequency Generation Spectroscopy ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Frequency Generation

scholarly journals Surface-enhanced Raman Spectroscopy and Density Functional Theory Study of Glyphosate and Aminomethylphosphonic acid Using Silver Capped Silicon Nanopillars

2021 ◽  
Vol 26 (1) ◽  
pp. 51-67
Author(s):  
John Castillo ◽  
Ciro Rozo ◽  
Kaiyu Wu ◽  
Tomas Rindzevicius ◽  
Anja Boisen
Keyword(s):  
Density Functional Theory ◽  
Raman Spectroscopy ◽  
Metal Surface ◽  
Density Functional ◽  
Surface Enhanced Raman Spectroscopy ◽  
Functional Theory ◽  
Binding Behavior ◽  
Aminomethylphosphonic Acid ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Glyphosate (GP) is a broad-spectrum systemic herbicide which is used for killing a wide variety of harmful plants. Several recent studies indicate possible adverse health effects on humans. This work is focused on detection and adsorption studies of GP and its metabolite aminomethylphosphonic acid (AMPA) on silver-capped silicon nanopillars using surface-enhanced Raman spectroscopy (SERS). Density Functional Theory with the B3LYP functional was employed for the geometry optimization of ground state geometries and simulation of Raman and SERS spectra of the GP and AMPA. The theoretically calculated and experimentally observed vibrations of GP and AMPA free and attached to the Ag surface exhibited different Raman spectra revealing chemical interactions between the analysed molecules and the metal surface. DFT studies confirmed that the main Ag-GP interaction is with the oxygen from carboxylic and phosphate groups, andfor AMPA the main interaction is via a strong interaction between nitrogen from NH with the metal surface. In order to study the binding behavior, adsorption isotherm analysis between GP and AMPA on silver-capped silicon nanopillars (AgNPs) were performed. Finally, the obtained isotherms for GP and AMPA followed a negative cooperative binding mechanism.

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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