Polarization Modulation with PEM for CD (courtesy Hinds Instr.)

SpectrometerUV or IR

Linearpolarizer PEM

Linear Dichroism Schematic (courtesy Hinds Instr.)

Linear Dichroism - Reflection (IRRAS) (courtesy Hinds Instruments)

Surface can be metal (high reflection, often grazing incidence)or dielectric, or even air-water interface

For film on liquid use Langmuir-trough for sample--studies of peptides and proteins in membranes possible, orientation from polarization

Variable angleof incidence

ATR Polarization Measurements

E

IR beam multiply reflects inside crystal -- penetrates surface keeps polarizations: Eperp in surface, Epara partially out

Sample coated on crystal

Crystal-Typ: Ge, ZnSeHigh index for refl.

In fromFTIR

out

Schematic – External reflectance FTIR & L-B trough

Dluhy, App.Spec.Rev.2000

k || y

E || zB || x

B | E

= c/x

z

y

Light—Electro-Magnetic (E-M) radiation

Tool for probing quantum mechanical states