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# Problem Set 1 Answers - ν = 8.46 MHz T 9T = 76.1 MHz The...

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Problem Set 1 Answers Chemistry 154A/254A: Quantum Chemistry Professor Song-I Han Teaching Assistant: Wang, Xiqing (Francis) Office: Chemistry 3223 Office: Chem 1126/ Dahlquist Lab (1 th floor) Office hours: Tue, Th 4-5 pm Office hours: Wed 1-2 pm and Fr 4-5pm Email: [email protected] Email: [email protected] temporarily Mark Lingwood ( [email protected] ) 1. (2 pts ea) Calculate all possible values of P z , and the Larmor frequency in a 9T magnet for 1. 19 F I = ½ m = -½, ½ P z = -½ ħ , ½ ħ γ = 40.06 MHz / T ν = 40.06 MHz / T * 9T = 360.5 MHz or γ = 25.181 × 10 7 rad / (T s) ω = 25.181 × 10 7 rad/(Ts) * 9 T = 2.266 × 10 9 rad/s = ν 2.266 × 10 9 rad/s / 2 π = 3.607 × 10 8 Hz = 360.7 MHz The frequency value may vary slightly depending on the γ used 2. 29 Si I = -½ m = -½, ½ P z = -½ ħ , ½ ħ γ = -8.46 MHz / T
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Unformatted text preview: ν = 8.46 MHz / T * 9T = 76.1 MHz The negative sign for is a convention, there is no such thing as a negative frequency γ 3. 2 H I = 1 m = -1, 0, 1 P z = - ħ , 0, ħ γ = 6.54 MHz / T ν = 6.54 MHz / T * 9T = 58.9 MHz 2. (4 pts) What is the pulse length for a 90º and 180º pulse, given the diagram? What happens if you acquire a spectrum with a single 180º pulse? a 90º pulse is 10 μ s a 180º pulse is 20 μ s if you perform a simple experiment with a single 180º pulse followed by an acquisition, you would observe no NMR spectrum. 3. (2 pts) Any pair of spectra ( 1 H, 13 C) taken from an online source were accepted. You can also find the SDBS by typing “SDBS” into Google and clicking on the first link....
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