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

2. Linear Dichroism Schematic (courtesy Hinds Instr.)
Spectrometer
UV or IR
Linear
polarizer
PEM

3. (courtesy Hinds Instruments)
Linear Dichroism - Reflection (IRRAS)
(courtesy Hinds Instruments)
Variable angle
of incidence
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

4. ATR Polarization Measurements
IR beam multiply reflects inside crystal -- penetrates surface keeps polarizations: Eperp in surface, Epara partially out
In from
FTIR
E
Crystal-
Typ: Ge, ZnSe
High index for refl.
out
Sample coated on crystal

5. Schematic – External reflectance FTIR & L-B trough
Dluhy, App.Spec.Rev.2000

6. Light—Electro-Magnetic (E-M) radiation
Tool for probing quantum mechanical states l
E || z
B || x
B | E
n = c/l x z y
k || y