Flashcards in Chapter 14 Deck (17):
P value between 0.1 - 1.0
high intensity. greater molar absorptivity
P value less than 0.1
low intensity. lower molar absorptivity
gas has less/more fine structure in wavelength vs abs.? why?
more. greater freedom of rotation/vibration
molar absorptivity =
PA(8.7*10^19) where P is probability, and A is molecule cross section
molar absorptivity range
electronic excitation lifetime in UV-vis
which has more fine structure in wavelength vs abs., organic nonpolar or polar?
Why are all organic compounds capable of absorption?
valence electrons can be excited
single bonds absorb in ? region
heteroatoms absorb in ? region
first two rows of transition series absorb in ? region
charge transfer absorption
electron donor bound to electron acceptor absorbs light. excited electron is transferred to acceptor.
charge transfer absorption results in?
high molar absorptivity and sensitivity, highly olored compounds
cause red shifts. OH and NH2. changes absorbance of parent molecule, but don't absorb UV. stabilize pi*
why choose UV-vis
1) easy; available and straightforward 2) low detection limit 3) selective 4) accurate