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

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