Question

For surface plasmon resonance (SPR), answer the following questions: a) Describe the experimental set-up of the Kretschmann configuration to excite a surface plasmon in a metal thin film? b) Draw the experimental set-up, how does the laser beam interact with the metal thin film, what is its polarization etc. label everything clearly. c) For the case of Gold thin film with ε--10 with air as the dielectric medium ε-1, if the prism has an index of refraction n 1.6 at λ-633nm, what should the incident angle of the laser beam so that a surface plasmon is excited? nsın6; E1(a) +82( d) Instead of air if water was the medium next to the gold film with ε-1.7 what would be the incidence angle then? (a)) . ε2(a) (n sin int) εί (a) + ε2(ω) .

You can solve only c) or d) ?

Answer 1

c) Given: - n = 1.6, E_1 = -10, E_2 = 1 (n sin theta_int)^2 = E_1(omega) middot E_2(omega)/E_1(omega) + E_2(omega) sin^2 theta_int = 1/n^2 E_1(omega) middot E_2(omega)/E_1(omega) + E_2(omega) = 1/(1.6)^2 -10 middot 1/(-10 + 1) = -10/2.56(-9) = 10/23.04 = 0.434 sin theta_int = squareroot 0.434 = 0.658 theta_int = sin^-1(0.658) = 41.147 degrees d) Given, n = 1.6, E_1 = -10, E_2 = 1.7 sin^2 theta_int = 1/2.56 (-10 times 1.7)/(-10 + 1.7) = -17/2.56 times (-8.3) = 17/21.248 = 0.8 sin theta_int = squareroot 0.8 = 0.894 theta_int = sin^-1(0.894) = 63.38 degrees