# H64SEN Tutorial

## Tutorial Question 2

Determine optical thickness of the layer deposited onto LPG fibre with the RI sensitivity of 100 nm/RIU if at the deposition the of 10 layers the wavelength shift of 20 nm was observed. Assuming the uniform film deposition and the thickness of 1 layer is 5nm and starting RI is 1.5.

Optical density = $$n \cdot d$$, where n = RI and d = Thickness

d = 10 x 5 nm = 50 nm

$$\delta RI = \frac{20\,nm}{100\,nm/RIU} = 0.2 \, RIU$$

total RI = 1.5 + 0.2 = 1.7

Therefore, optical thickness = $$n \cdot d$$ = 85 nm

## Tutorial Question 3

Calculate surface coverage resolution if red light (632nm) strikes glass (RI=1.47)-water (RI=1.32) interface at 61o incident angle if the analyte RI increment is 0.2 cm3/g and SPR RI resolution is 10-6 RIU

$\sigma_{\Gamma} = \sigma_{RI} \frac{L_{pd}}{2(\frac{\delta n}{\delta c})}$

$L_{pd} = \frac{\lambda}{ 2 \pi \sqrt{ (\frac{n_2}{n_1})^2 - \sin^2 \theta}}$

$n_1 = 1.47$

$n_2 = 1.32$

$\frac{\delta n}{\delta c} = 0.2 cm^3/g$

## Tutorial Question 4

Sketch the typical cyclic voltammogram for reversible redox reaction. Label oxidation and reduction peaks.

## Tutorial Question 5

Sketch the diagram of the interferometric optical fibre sensor based on tapered coupling elements. Sketch the typical transmission spectrum of such device