Curs de Biofizică

Prof.dr. Cipriana ŞtefănescuDisciplina de Biofizică

şi Fizică medicală

10

Vă rugăm: gândiţi!

Fenomene optice si spectre

Dispersia luminii albe

http://upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif

Difracţie

Colors seen in a spider web are partially due to diffraction, according to some analyses.[1]

Reflexie

Refracţie

Reflexie totală

Relation between different typesof spectra and their principle

electron level

changes

Gamma ray and X-ray quantum energies are so high that they cause ionization

Numberof available

energy states

molecular vibration

X-ray scattered

X-ray

molecular rotation and

torsion

X-ray

ionizationionization accompanied by Compton scattering

ultraviolet

visible light

infrared

microwaves

High,strongly

absorbed

Small,almost

transparent

Ionization energy

Principiul fizic de producere aspectrelor de emisie şi de absorbţie

E2

Spectru de absorbţie

E1

ΔE

Spectru de emisie

ΔE = hν1

Spectrul luminii albe(R, O, Y, G, B, I, V)

absenţa ν1

Linie neagră

Fond negru

emisia ν1

Linie în culoarea corespunzătoare frecvenţei

Spectre de emisie

Spectre du Mercure : Spectre du Néon :

Spectre du Cadmium :

Spectre du sodium :

Spectre de absorpţie

Types of spectra related to the energy quantum and the type of structural phenomenon, at the electromagnetic radiation interaction with matter

Phenomenon Region of spectrum

Wavelength(nm)

Nuclear Gamma 0.1 nmInner electrons X-rays 0.1 – 1.0 nmIonization Ultraviolet (UV) 0 – 200 nmPeripheral (valence)

electrons Near UV and

visible200 – 800 nm

Molecular vibrations Near infrared (IR)and IR

800 – 2500 nm

Rotation and electron spinorientation in magneticfields

Microwaves 400 μm – 30 cm

Nuclear spin orientation inmagnetic fields

Radiowaves 100 cm and above

Spectrul electromagnetic