On the origin of optical activity in inorganic crystals

Power dependence on the rotational strength in a quartz crystal

“…1 shows the plot of the angle of rotation V s the square root of the intensity of radiation. As expected, a straight line is observed which confirms the previous proposed model [5] and strengthens our views about the role of dominating polarizability from bent bonds rather than from atomic polarizability. This is the first time that the role of incident power on the angle of rotation has been detected which was anticipated recently [5].…”

“…There are also some other materials like nano-particles and organic compounds which show optical activity. Recently the origin for the optical activity is associated with the charge distribution of bent bonds [5] originated from the presence of vacancies (electronic polarizability). The displacement of the charge distribution from the equilibrium configuration creates an electric dipole moment [13] near the vacancy.…”

“…The electric vector, E, also affects the amount of charge or percentage of charge displaced; however, the effect is small as compared with the change in the configuration. A detailed study of this parameter has been carried out earlier [5].…”

“…Optical activity was first observed by Biot in 1812 and since then, several theoretical models have been proposed [1][2][3][4][5] to explain its origin. In spite of numerous and constant attempts, the success is limited both on the theoretical as well as on the experimental aspects.…”

“…for higher intensity, the electric field vector has higher magnitude and hence the dipole strength is higher. This key feature has been taken into account by Joshi [5]. However, the role of this parameter has not been examined experimentally so far.…”