FC chemistry in the ionosphere

Question 1

what species persist in the ionosphere

Answer 1

N2, O2, CO2 and even trace amounts of H2O, Atoms (H, N, O) and radicals (OH, NO)

Question 2

describe the chemistry in the ionosphere

Answer 2

low densities mean slow reaction but high UV energies can produce very reactive excited or even ionised species.
charged particles e.g electrons, protons, ions play a crucial role in ionospheric chemistry.

Question 3

describe the F region

Answer 3

the F region is located above 150km, is dominated by atomic ions e.g O+, N+ and at the highest altitudes, H+ and He+ beyond 1000 km

Question 4

describe which wavelengths of radiation reaches the F1 and F2 region

Answer 4

Radiation of all wavelengths reaches the F2 region,
whereas 20-90 nm radiation ionises the F1 region

Question 5

describe the E-region

Answer 5

E-region (100-150 km) is where molecular ions become more important, e.g. NO+ and O2+

Question 6

what radiation ionises the E region

Answer 6

Extreme ultraviolet radiation 80-103 nm ionises the E-region

Question 7

describe the D region

Answer 7

D-region (below 100 km) is more complex: lowest T vs. relatively high pressures; hydrated protons and water-cluster ions become common; electron loss is due to negative ion formation

Question 8

describe the surviving radiation in the D-region

Answer 8

the only surviving radiation in the D-region is above 103 nm

Question 9

Describe airglows

Answer 9

driven by photons from the sun, faint natural glow of night sky caused by photochemical reactions e.g molecules absorbing solar UV radiation during the day and remitting it at night
H(2S) + hv(solar) -> H(2P) -> H(2S) + hv(airglow)

Question 10

Describe aurora

Answer 10

auroras are excited by solar particles, bright light displays near polar regions caused by interactions between solar wind and magnetic fiels

Question 11

What is light emitted in ionosphere due to

Answer 11

light in ionosphere is emitted due to excitation/relaxation of atoms (O, O2, N2)

Question 12

What is a photochemical reaction

Answer 12

photochemical reactions - absorption of high energy photos excites atoms, return to low energy and emit photon

Question 13

What is chemiluminescence

Answer 13

reactions produce excited species that emit photons

Question 14

What is the visible spectrum of light wavelength

Answer 14

375-790 nm

Question 15

How do we know if the light is emitted via fluorescence of phosphorescence

Answer 15

fluorescence - same spin states in transitions which is spin allowed
Phosphorelescence - difference in spin transitions for example singlet to triplet transitions which is formally spin forbidden