DETERMINACIÓN DE ESTRUCTURAS ORGÁNICAS(ORGANIC SPECTROSCOPY)
UV/VIS SPECTROSCOPY
Hermenegildo García GómezHermenegildo García GómezDepartamento de QuímicaDepartamento de Química
Instituto de Tecnología QuímicaInstituto de Tecnología QuímicaUniversidad Politécnica de ValenciaUniversidad Politécnica de Valencia
46022 Valencia46022 Valencia
EE--mail: mail: [email protected]@qim.upv.esTelephone: +34 96 387 7807 or ext. 78572/73441Telephone: +34 96 387 7807 or ext. 78572/73441
Fax: + 34 96 387 7809Fax: + 34 96 387 7809
UV/VisA typical UV/Vis Basic equation of all spectroscopics
chhc
hE υλ
υ ===∆
E∆ Difference in energy of thequantized levels of a compound
chhc
h υλ
υ == Wave energy
Diagram of electronic levels
I0I
b
Sample0II
T =
=
II
A 0
10log
kcbA =
Transmittance
Absorbance
Lambert-Beer Law
c = concentration K = molar absorptivity
DefinitionsCHOMOPHORE. A covalently unsaturated group responsible for electronic absortion (for example, C=C, C=O, and NO2).
AUXOCHROME. A saturated group with nonbonded electrons which, when attached to a chromophore, alters both the wavelength and the intensity of the absorption
BATHOCHROMIC SHIFT. The shift of absorption to a longer wavelength due to substitution or solvent effect (a red shift).
HYPSOCHROMIC SHIFT. The shift of absorption to a shorter wavelength due to substitution or solvent effect (a blue shift).
HYPERCHROMIC EFFECT. An increase in absorption intensity.
HYPOCHROMIC EFFECT. A decrease in absorption intensity.