1. Fourier Transform Infrared Spectroscopy (FTIR) is often used in determination of chemical bonds of various organic compounds. In general practice, the sample (can be either solution or solid) is placed on top of a diamond surface (that is attached to the FTIR system), while the beam, can be either TE or TM mode, would be incident towards the diamond. The beam would interact with the sample, subsequently internally reflected. A simplified on the sensing mechanism is shown in Figure 1. diamond n = 2.4 medium x Figure 1: Simplified sensing mechanism of FTIR system. The sample to be scanned is named "medium x". (a). If the medium is air, (i). Determine the reflectance when the incident angle where the beam propagate from diamond to air being zero (normal incidence). [10 marks] (ii). Give the name about the mode of light (TE or TM) where the reflected light can be zero. 1 [10 marks] (iii). Determine the angle of such case. [10 marks] (iv). Give the name of such angle. (v). Determine the critical angle for this configuration. [10 marks] [10 marks] (b). Consider medium x is now butanol with refractive index of 1.3993. Using Question 1(a)(i) to (v) as guides, illustrate the reflectance plot of the diamond-butanol configuration with incident angle ranging from 0 to the critical angle. (You need to use graphical software for this question, remember to provide labels as well). [50 marks]