Linear Dichroism

Linear dichroism (LD) is the differential absorption between two orthogonal, linearly polarized states (A = A_X – A_Y). LD is a measurement of the sample’s bulk property that is a result of the regular orientation of the molecules in the sample.

SETUP

PEM Setting: half-wave retardation (λ/2)
Polarization Modulation: bottom || and ⊥ linear polarization
Lock-in reference: PEM’s 2nd harmonic (2f)

POLARIZATION MODULATION

After the PEM, the light beam is modulated between two perpendicular, linearly polarized states at the modulator’s 2nd harmonic (2f)

APPLICATIONS

Structural study and characterization in inorganic chemistry, polymer chemistry, material science, and biochemistry.

PEMs

I/FS50 for UV-vis

II/FS42  for UV-vis and near IR

FURTHER READING

T. C. Oakberg, Application Note – Linear and Circular Dichroism, Hinds Instruments, Inc. (1991).

A. F. Drake, “Polarisation modulation-the measurement of linear and circular dichroism,” J. Phys. E: Sci. Instrum. 19, 170 (1986).

B. Norden, Appl. Spectrsc. Rev.14, 157 (1978).

Linear & Circular Dichroism

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