Compound

Absorption Function and Eg (eV)

Nature of Transition

Range of Absorption Function (cm⁻¹)

Pinacyanol chloride

Direct allowed Transition

1650 - 3000

Pinacyanol chloranil (PC-Cl)

Direct allowed Transition

1750 - 3000

(PC-Cl)-DDQ

Direct forbidden Transition

1670 - 3000

(PC-Cl)-TCNQ

Direct forbidden Transition

1700 - 2200

(PC-Cl)-TCNE

Direct forbidden Transition

1750 - 3100