Chapter 19 Flashcards Preview

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Flashcards in Chapter 19 Deck (15):
1

in NMR, you irradiate with radiofrequency of ? to ? hz

2-900

2

basis of NMR

molecule absorbs and emits detectable radiofrequency

3

peaks on left side of NMR spectrum

low field, low shielding, high frequency

4

peaks on right side of NMR spectrum

high field, high shielding, low frequency

5

deshielded

high electronegativity of surrounding atoms

6

shielded

aligned with magnetic field

7

higher shileding requires more/less magnetic field to bring nucleus into resonance with radiofrequency

more

8

? creates an induced magnetic field

spinning charge

9

positive 1/2 spin

aligned with magnetic field, lower energy

10

negative 1/2 spin

opposite of magnetic field, higher energy

11

chemical shift

relative number based on internal standard, TMS (highly shielded)

12

splitting =

neighboring nuclei +1

13

COSY

2D NMR

14

MRI

3D NMR

15

problem with NMR. how fixed?

magnet drift. lock frequency with deuterium, shim (fine-tune) the magnet, spin the sample.