Chapter 15 Flashcards Preview

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Flashcards in Chapter 15 Deck (17):
1

? and ? are excitation due to absorption of photons

fluorescence and phosphorescence

2

fluorescence

absorbs radiation then relaxes from singlet to ground state emitting radiation. from 10^-10 to 10^-5 sec

3

phosphorescence

absorbs radiation, change in electron spin. relaxes from triplet to ground state emitting radiation. 10^-4 to 10 sec

4

internal conversion

radiationless transition to lower excited state of same multiplicity

5

external conversion

releasing radiation to solvent

6

intersystem crossing common with >

heavy atoms and O2/ paramagnetic

7

intersystem crossing

crossover in multiplicity (ie. S to T)

8

triplet state is paramagnetic/diamagnetic

paramagnetic

9

variables that affect luminescence

rate of internal conversion, external conversion, intersystem crossing, predissociation, dissociation

10

relaxation from pi* produces high/low fluorescence

high

11

structures with high fluorescence

aromatics, rigid

12

decreasing temperature increases/decreases fluorescence

increases (less external conversion)

13

pH effects

molecule charge can give more resonance. Gives more stable excited state.

14

static quenching

quencher and ground-state fluorophore form a dark complex

15

spectrofluorometer sources

high intensity. Hg-vapor, Xe-arc, laser

16

ion analysis

bind ion to fluorometric reagent

17

chemiluminescence

emission of radiation formed during a chemical reaction