ElectroMagnetic Radiation Characteristics Light beam characteristics wavelength frequency
Electro-Magnetic Radiation Characteristics • Light beam characteristics - wavelength (frequency), intensity, polarization - determine types of transitions and information accessed • Energy: Q, Flux: =d. Q/dt; Intensity: I=d /d • Source radiance: B(l)=d 2 /(d d. Ascos • Irradiance on Detector: E=d /d. Adet z E || z B || x y B | E x l n = c/l k || y
![Light Polarization [courtesy Hinds Inc. brochure] Rlin = 0 Linear Polarization Preserved in isotropic](http://slidetodoc.com/presentation_image_h2/d2f90b04d99246222ecb0b4ce3a2a21d/image-2.jpg "Light Polarization [courtesy Hinds Inc. brochure] Rlin = 0 Linear Polarization Preserved in isotropic")
Light Polarization [courtesy Hinds Inc. brochure] Rlin = 0 Linear Polarization Preserved in isotropic medium RR = l/4 Right Circular Polarization RL = -l/4 Left Circular Polarization Phase retard orthogonal polarizations forward or back with birefringent medium
Light Polarization Modulation PEM oscillates phase retardation & sense circular polarization k Right Circular Polarization k Left Circular Polarization
Light (E-M Radiation) Characteristics • Frequency matches change in energy, type of motion E = hn, where n = c/l (in sec-1 or Hz) • Intensity increases the transition probability— Absorbance I ~ e 2 –where e is the Electric Field strength in the radiation • Absorbance is ratio A = -log(I/Io) • Linear Polarization aligns to direction of dipole change A ~ [dm/d. Q]2 where Q is the coordinate of the motion Circular Polarization results from an interference: R ~ Im(m • m) m and m are electric and magnetic dipole A hn IR of an oil C-H C=O CH 2 C-C
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