There is a one-dimensional solid lattice with two basis atoms of mass m and M, respectively (lattice constant = a). Let the interaction between atoms act only on adjacent atoms, and let the bonding force coefficient be C (Fig.). M C C a a) Draw the Brillouin zone and the approximate phonon dispersion w=w(K), and write the name of each phonon branch b) When K = TT/a, write down the normal mode energy and discuss the relative motion of adjacent atoms. c) If two atoms are of the same kind (m = M), plot the Brillouin %3D zone and phonon dispersion w=w(K).

The following (Attached image) is an external quantum efficiency of a CZTS solar cell with structure Glass/Mo/CZTS/CdS/AZO/Ag. The ideal QE curve would be a rectangle (red curve). The experimental QE is much less than the ideal one because of losses at different regions outlined 1, 2, 3 and 4. Please explain what are those losses.

o+ %) Which of the following statements are true? (Select allthat apply). Your answer: O The series converges to some finite number L. {1 The series conditionally and absolutely converges. O Itis an alternating series. O The series absolutely converges. O The series converges conditionally. 1 1 3 —(9 + 7) diverges. B &y ) o Itis not an alternating seri O The ratio test is inconclusive.