How does changing thickness affect the SPR peak in air?


Above you can see an animation which explains what happens to SPR curves when measuring nanolayers in air or gas. The fact that the measurement is performed in air can be seen from the position of the Total Internal Reflection (TIR) region around 40 degrees. While traditional SPR, such as Biacore, is suited only for measurements in liquid (range of 1.33 to 1.38 of RI, which corresponds roughly to 65 to 75 degrees of angular range), MP-SPR works also in air (range of 1.0 to 1.45 of RI, which corresponds roughly to 38 to 78 degrees of scanning angular range). This animation also shows a formation of a waveguide for thicker nanolayers. MP-SPR is ideally suited for dynamic measurements of material swelling and conformational change, e.g. from dry to wet state. 

On use of this animation: Feel free to use this animation for educational purposes. Please, remember to refer to the original source, e.g. '', BioNavis Ltd - Excellence in Surface Plasmon Resonance, Finland''. If you are our customer, remember to request a complementary set of PowerPoint slides about the MP-SPR technology.

See also other animations that explain the SPR curve changes in relation to nanolayer thickness and refractive index change:

How does the SPR peak respond to change in thickness in water?                                                                  



Surface measured with two different wavelengths (here 785 nm and 670 nm). The thickness remains the same in both cases. The difference in the curves is due to the change of refractive index in relation to the measured wavelength. See animation.

How does the SPR peak respond to change in thickness when the sample absorbs light? 



Light absorbing samples, such as porphyrins or gold and silver nanoparticles, cause intensity changes to meaured curves. See animation.