Lecture 27 - Spectroscopy

Lecture 27 - Spectroscopy - Final Exam Fri, Mar 18, 2011...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Final Exam Fri, Mar 18, 2011 10:30 – 12:30 pm 198 Young (last name begins with “A” - “M”) 176 Everson (last name begins with “N” - “Z”) Chapters 2.6 – 2.9, 9, 10.1 – 10.5, 11, 12.1 – 12.7, 13.1 – 13.4, 14.1, 14.3 – 5 Closed Book and Closed Notes No electronic devices except calculator At least one assigned homework problem will appear on the exam. Review session on Thu Mar 17 at 6:00 pm in 1100 Social Sciences. Practice Final Exam on website. 40-50%
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Nuclear Magnetic Resonance (NMR) I Neutrons Protons Spin ( I ) Examples even even 0 12 C 6 , 16 O 8 even odd ½ 1 H, 15 N 7 , 19 F 9 odd even ½ 13 C, 31 P odd odd 1 2 H, 14 N Δ E = ħ ω 0 = ħ γ B 0 HO – CH 2 –CH 3 2 0 B E γ α h = 2 0 B E β h = ν (MHz) 0 0 B ω = π ν 2 0 0 = = h ν 0 2 h = h 10 6 -fold smaller than Δ E for e- transition
Background image of page 2
I Time Domain vs. Frequency Domain α β B o Δ E = ħ γ B 0 Nuclear Magnetic Moment ( μ ) vs Time: μ = γ I μ x = cos( ω 0 t) real axis i μ y = isin( ω 0 t) imag axis (i) μ x,y = μ x + i μ y = e -i ω 0t Frequency Domain (MHz) ν Frequency (MHz) Zeeman Splitting ( Δ E = ħ ω 0 ) Larmor Precession ( ω 0 = γ B 0 ) d μ (t)/dt = γμ (t) × B 0 (t) FT ν = γ B o /2 π = 800 MHz Δ E = 3 x 10 -25 J 2 0 B γ h 2 0 B h + ω 0 = γ B 0 FID(t) 0 B E = μ 10 6 -fold smaller than e- transition
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
( ) () J h T s T E 25 1 1 7 10 35 . 5 2 8 . 18 10 75 . 26 × = × = Δ π Energy difference at a magnetic field of 18.8T: Boltzmann population (300K): Absorption is proportional to net concentration of ground state ( Δ N = N α –N β ) NMR Absorption is 10000-fold weaker than for IR (need mM or higher). Higher magnetic field increases E and N and hence increases sensitivity. E β E α ħ ω 0 = E β -E α 99987 . 0 / 10 3 . 5 25 = = = × Δ kT T k E e e N N B Population of vibrational states: % 04 . 0 10 4 4 / 10 5 0 1 20 = × = = = × Δ = = kT T k E v v e e N N B γ αβ 2 0 h B E E E = = Δ 1 99987 . 1 99987 . 0 = × = × + = + αα βα N N N N N 00026 . 0 × = = Δ N N N N 5 10 2 . 6 99987 . 1 99987 . 0 1 1 1 × = = + = = = Δ N N N
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/06/2011 for the course CHEM 107B taught by Professor Jamesames during the Winter '09 term at UC Davis.

Page1 / 21

Lecture 27 - Spectroscopy - Final Exam Fri, Mar 18, 2011...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online