Sum frequency generation (SFG) microscopy images of cotton cellulose fibers were observed at the infrared wavenumber of ~ 2945 cm(-1) and with a spatial resolution of 2 μm. Domains of different cellulose microfibril bunches were observed and they showed different second-order nonlinear responses. The intensity of the peak of the asymmetric CH(2) stretching mode at 2945 cm(-1) depended strongly on the orientation of the electric fields of the incident visible and infrared light with respect to the cellulose fiber axis. The second-order nonlinear susceptibility arising from the chirality in the cellulose structure was found to be dominant. The SFG of the cross section of the cellulose fiber was relatively weak and showed a different spectrum from that measured from the side of the fiber axis.
This article describes a simple numerical simulation of three-layer surface plasmon resonance (SPR) in the Kretschmann configuration. The calculation was performed in Google Sheets, a web-based spreadsheet environment that functions similarly to Microsoft Excel where it is easily accessible for students via the internet. Specifically, Fresnel’s equations were utilized to calculate the intensity of the reflected light for the p-polarized incident light on a three-layer system. The complex functions were utilized to plot the SPR curves. We examined the change of the resonance angle by the influence of the incident wavelength. The simulation was also performed for different thicknesses of the gold film layer. To demonstrate the sensitivity, we obtained the SPR curves with the variation of the refractive index in the sensitive medium. The SPR accuracy was analysed by comparing our obtained result with the published work. It is intended to incorporate into undergraduate instrumental analysis courses.
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