Photochemistry

Question 1

Prompt Photodissociation

Answer 1

one molecule excited for each photon absorbed

so fast there is no clear excited state

Question 2

Wavelength Dependence

Answer 2

change wavelength of irradiation change photochemistry

Question 3

Delayed Photoreaction

Answer 3

electron excited into excited state
converted to a second excited state
then reacts

Question 4

Typed of Excited State

Answer 4

metal centred
intraligand
ligand-metal charge transfer: need lone pair
metal-ligand charge transfer: need d electrons
metal-metal charge transfer
metal-metal bonding

Question 5

Franck-Condon

Answer 5

absorption from one low level to many upper levels
emission from one upper level to many lower levels
0->0 same peak
mirror image spectra

Question 6

Photoluminescence

Answer 6

light shon on a sample

Question 7

Fluorescence

Answer 7

luminescence, no change in spin state

Question 8

Phosphorescence

Answer 8

luminescence, change in spin state

Question 9

Electroluminescence

Answer 9

apply potential within

out comes light

Question 10

Absorption

Answer 10

scan wavelengths of light coming in

absorbance vs. yex

Question 11

Emission

Answer 11

measure intensity of emission
Iem as function of yem
yex constant

Question 12

Excitation

Answer 12

Iem as function of yex

yem constant

Question 13

Selection Rules

Answer 13

spin
gu
asymmetric d->d

Question 14

MLCT

Answer 14

absorption from ground state to 1(MLCT) state

emission from 3(MLCT) to ground state

Question 15

Electron Transfer Redox

Answer 15

-ve potential, reducing

+ve potential, oxidising

Question 16

Long Distance Electron Transfer

Answer 16

attach Ru(bpy)22+ to protein surface via histidine 
repeat with different histidines at known distances from haem

Question 17

DNA Probe

Answer 17

Ru(phen)2(dppz)2+ emits in presence of DNA

intercalates in chain

Question 18

Solar Battery

Answer 18

electricity using light
TiO2 nanoparticle
electrons into conduction band

Question 19

Light Emitting Diode

Answer 19

cathode provides electron

anode supplies hole

Question 20

Organic Light Emitting Diode

Answer 20

charge injection
charge transport
exciton formation
emission

Question 21

Full/Empty Orbital

Answer 21

(t2g)0 or (t2g)6

1A1g

Question 22

1 Electron or 1 Hole

Answer 22

(t2g)1 or (t2g)5

2T2g

Question 23

2 Electrons or 2 Holes

Answer 23

(t2g)1(eg)1 = T1g + T2g

singlets and triplets of each

Question 24

Gas Phase

Answer 24

one photon absorbed can cause loss of several ligands

excess energy remains and causes sequential losses