บทที 12 สมบัติอืนๆ ของวัสดุ

http://www.chemsoc.org/exemplarchem/entries/2002/AmandaThompson/Frame3b.htmFerromagnetismOptical propertiesAntiferromagnetismFerrimagnetismFerromagnetic Curie temp, T cParamagneticAntiferromagnetic Neel temp, T N ParamagneticFerrimagnetic Curie temp, T cParamagnetic49Light, heat (or radiant energy), radar, radio waves, γ-rays, x-rays50∆E = hf =hcλh = Planck’s constant= 6.63x10 -34 J.sLight-Solid InteractionsI = I + I + I0TART + A + R=151c =1ε µ0c = fλ0c = velocity in vacuum = 3x10 8 m/sε 0 = electric permittivity of vacuumµ 0 = magnetic permeability of vacuumf = frequency (Hz)λ = wavelength52I 0IIITAR====Intensity of incident beamIntensity of transmitted beamIntensity of absorbed beamIntensity of reflected beamT = ITA = IR = IAR/ I0/ I/ I0053Index of refraction, nReflectivityR =ถ้าแสงตกกระทบตังฉากกับผิวของแข็งcn =vถ้าแสงเดินทางจากอากาศหรือสุญญากาศมายังของแข็งIRI 0⎛ nR =⎜⎝ n22⎛ nR =⎜⎝ nss− n+ n11⎞⎟⎠−1⎞1⎟+ ⎠22Applications of optical phenomenaLuminescence• ดูดกลืนพลังงานแล้วปล่อยออกมาในรูปของ visible light• fluorescent lamp, TV screen, LEDs for digital displaysLasers• Solid-state: ruby (0.05%Cr 3+ ), Nd-Glass• Metal vapour: HeCd• Gas: He-Ne, CO 254PhotoconductivityOptical fibers in communications