I would like to ask questions about how the adsorbed molecular influence frequency and intensity of surface plasmon resonance of metals such as Ag and Au.
Does the adsorption of molecular influence the frequency and intensity of SPR simultaneously?
Or will different adsorption configurations of the same molecular have specific influences? (just for example, linear adsorption will only influence the intensity but bridge adsorption influence frequency and intensity simultaneously?)
Could you recommend some answers or papers (books)? Thank you so much.
you can read the following:
1. Article Design of electric-field assisted surface plasmon resonance ...
2. https://www.photonics.ethz.ch/fileadmin/user_upload/Courses/NanoOptics/plasmonss.pdf
Dear Xu Xuanwen ,
The adsorption of molecules on a metal layer or on a metallic nanostructure induces small variations in the refractive index of the medium located in contact with the metal, and as a result, changes in the excitation of Surface Plasmon Polaritons (SPPs) or Localized Surface Plasmon Resonances (LSPRs), respectively, are induced. Those effects have been used to develop different types of optical and magneto-optical biosensors. There are many papers reporting that, for instance please have a look at these two for examples of LSPR-based and SPP-based sensors:
Article Localized Surface Plasmon Resonance Sensing of Lipid-Membran...
Article Enhanced antibody recognition with a magneto-optic surface p...
However, I’m not sure if the difference in the type of adsorption can be detected, probably only if the number of molecules per unit area is strongly affected (since this phenomenon would produce different “effective refractive index”), although I’m not a specialist on that.
Xu Xuanwen, A well-localized, evanescent SPR field is excited surface absorbed molecules. Then this field is re-emitted due to their own oscillations with a frequency of incident light. These oscillations are specific to the kind of absorbed molecules, their index of refraction, concentration (so, SPR intensity), other optical properties. In such a way, absorbed molecules influence on optical properties of the whole SPR system.
Strong surface localization of the SPR field produces strong sensitivity to only surface absorbed molecules and their state, which can be changed due to some specific reaction. Such effect is the origin of SPR application as chemical, biological sensors of different kinds.