[Illinois] ECE 416 Surfance Enhanced Raman Spectroscopy I

By Brian Cunningham1, NanoBio Node1

1. University of Illinois at Urbana-Champaign

Published on

Abstract

           In this lecture, we started with the concept of a surface enhanced raman spectroscopy. It was observed that it is a powerful measurement technique, but the Raman scattering is a very weak effect. We see that the surface plays a role in this detection method as it is metal that has a huge abundance of electrons. The electric field of coherent light oscillates the electrons as a collective group. The surface is also rough which allows the electrons to oscillate in a direction parallel to the surface. The result is a buildup of extremely large electromagnetic fields at "hot spots" on peak tips. This produces the electromagnetic enhancement effect in which a molecule experiences a greater electromagnetic field than it would ordinarily. It also produces the chemical enhancement effect in which there is a transfer of electrons between the metal and molecule. When the molecule comes into close physical contact with the surface it can be adsorbed or chemically bonded. The electromagnetic enhancement theory is then looked at in relationship to the sphere model and we see that the greatest Raman coupling occurs when the molecule is adsorbed on the surface and oriented with its main axis perpendicular to the surface. The scattering strength and wavelength is strongly dependant on the size of the metal sphere. The enhancement factor is then looked at and how the plasmon Electric field induces a dipole in an adsorbed molecule at the laser wavelength. The molecule emits a Raman-shifted electromagnetic field at a new wavelength. The new wavelength also induces a second dipole in the sphere at the Raman-shifted wavelength. After that examples and are shown in relationship to nanospheres and the Surface Enhanced Raman Spectroscopy.

Cite this work

Researchers should cite this work as follows:

  • Brian Cunningham; NanoBio Node (2013), "[Illinois] ECE 416 Surfance Enhanced Raman Spectroscopy I," https://nanohub.org/resources/17706.

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Time

Location

University of Illinois, Urbana-Champaign, IL

[Illinois] ECE 416 Lecture 37: Surfance Enhanced Raman Spectroscopy I
  • Surface Enhanced Raman Spectroscopy 1. Surface Enhanced Raman Spectro… 0
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  • Motivation 2. Motivation 18.093512376638085
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  • Outline 3. Outline 221.05263157894737
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  • History 4. History 241.7684210526316
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  • What is special about a metal surface? 5. What is special about a metal … 482.08421052631576
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  • What is special about a rough surface? 6. What is special about a rough … 619.45263157894738
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  • Then what happens? 7. Then what happens? 738.50526315789477
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  • What is special about a rough surface? 8. What is special about a rough … 776.46315789473681
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  • Then what happens? 9. Then what happens? 848.84210526315792
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  • Electromagnetic Enhancement Theory 10. Electromagnetic Enhancement Th… 910.37631451221489
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  • Sphere model 11. Sphere model 1293.4850299401198
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  • SERS Enhancement Factor (EF) 12. SERS Enhancement Factor (EF) 1425.3872794950639
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  • SERS EF 13. SERS EF 1620.3319605252934
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  • Theoretical Calculations 14. Theoretical Calculations 1749.7049498795554
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  • SERS Surfaces 15. SERS Surfaces 1754.7941565001165
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  • Nanosphere Lithography 16. Nanosphere Lithography 1805.137679987057
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  • SERS Surfaces 17. SERS Surfaces 1868.2019744295194
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  • Nanosphere Lithography 18. Nanosphere Lithography 1929.3183363003723
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  • SERS Surfaces 19. SERS Surfaces 1985.3292347516583
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  • Nanosphere Lithography 20. Nanosphere Lithography 1996.1372390354427
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  • Nanosphere Lithography 21. Nanosphere Lithography 2080.0637643631658
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  • SERS Surfaces 22. SERS Surfaces 2083.1629713545881
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  • MFON (or AgFON) Coupling 23. MFON (or AgFON) Coupling 2140.6842531153907
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  • Demonstration of distance dependence of SERS 24. Demonstration of distance depe… 2174.5675457045786
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  • SERS Applications 25. SERS Applications 2276.305551060042
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