Magnetic Circular Dichroism - Theory

Theory

Consider a system are of localized, non-interacting absorbing centers. Based on the semi-classical radiation absorption theory within the electric dipole approximation, the electric vector of the circularly polarized waves propagates in the +z direction, where + and -denote to RCP light and LCP light respectively. In this system, ω = 2nν is the circular frequency, and Ii = n – ik is the complex refractive index. As the light travels, the attenuation of the beam is expressed as

I(z) = I0exp(−2ωkz/c)

where k is the absorption coefficient of the medium in the z direction. Circular dichroism (CD) is then defined as Δk = k – k+, and it follows the sign convention of natural optical activity. In the presence of the static, uniform external magnetic field, the Hamiltonian for the absorbing center takes the form Ĥ = Ĥ0 + Ĥ1 which is parallel to the direction of the propagation of the electric field k. Because the transition occur between the two eigenstates of Ĥ0, a and j, the absorption and the CD intensity are determined as follows:

Read more about this topic:  Magnetic Circular Dichroism

Famous quotes containing the word theory:

    There is in him, hidden deep-down, a great instinctive artist, and hence the makings of an aristocrat. In his muddled way, held back by the manacles of his race and time, and his steps made uncertain by a guiding theory which too often eludes his own comprehension, he yet manages to produce works of unquestionable beauty and authority, and to interpret life in a manner that is poignant and illuminating.
    —H.L. (Henry Lewis)

    Lucretius
    Sings his great theory of natural origins and of wise conduct; Plato
    smiling carves dreams, bright cells
    Of incorruptible wax to hive the Greek honey.
    Robinson Jeffers (1887–1962)

    ... liberal intellectuals ... tend to have a classical theory of politics, in which the state has a monopoly of power; hoping that those in positions of authority may prove to be enlightened men, wielding power justly, they are natural, if cautious, allies of the “establishment.”
    Susan Sontag (b. 1933)