Nuclear Magnetic Resonance ANIMATED ILLUSTRATIONS MS Powerpoint Presentation Files Uses Animation Schemes as available in MS XP or MS 2003 versions A class room educational material File-1 FT NMR-1D http://ugc-inno-nehu.com/links_from_web.html 12/5/2018 11:37:06 PM Dr.Aravamudhan

tm t1 t2 Acquisition for duration t2 ω1 ω2 Evolution period t1 Mixing period tm (Fixed duration) t1 tm Acquisition for duration t2 t2 Depends on the choice of the type of 2D experiment ω2 ω1 2D Spectrum Contour plot 2D NMR pulse sequence structure

There has been no MULTIPLE PULSE SEQUENCE considered in this illustration. This only to illustrate the spectrometer settings required while setting up multiple pulse experiments. Two dimensional spectra contain rich information if the spin system is allowed to evolve under multiple pulse perturbations before acquisition of FID.

A typical two pulse sequence for 2D experiment mixing (π/2)y Prepararion Acquisition t 2 Evolution t1 M0 R This sketch above and the 2D consequent would be elaborated at a later stage to follow. y x A description of multiple pulse 2D experiment: A generalized depiction below……….. Preparation Evolution t1 Mixing t ime τ Detection t2 t1 is varied from scan to scan τ is fixed acquisition

P2y P1x P2y P2y τ is fixed t1 is varied from scan to scan Z-axis Y-axis Spin system evolves freely; Magnetization vector precesses in XY plane P1x X-axis For the ‘Y’ axis π/2 pulse the component along –X axis gets to -Z direction Typical spin system manipulation by multiple pulse sequence for two dimensional experiments Precession by about 45°: can be resolved into components along X and Y axes P2y If the Spin system continues to evolve freely without any intervening pulses, Magnetization vector precesses in XY plane by angle π/2 so that the entire magnetization would be along –X axis. Thus the magnetization vector is sent to –Z direction by this pulse along Y-axis P2y Preparation Evolution t1 Mixing t ime τ Detection t2 t1 is varied from scan to scan τ is fixed acquisition 12/28/2010 8:47:59 AM Dr.Aravamudhan

Experiment with increasing t1 , the evolution time :increment 10μs How will the FT for each of this FID would look? Scan 1 3 2 3 3 4 4 4 3 3 2 2 2 3 3 3 2 2 2 8 6 4 2 1 2 4 5 6 5 2 5 4 1 4 3 3 4 5 5 DW =5μs Scan 2 3 3 2 2 4 3 2 3 2 2 1 2 4 5 6 5 3 2 4 4 3 2 2 1 4 3 2 3 3 4 4 5 5 5 4 3 Scan 3 3 3 2 2 2 1 2 4 5 6 5 4 3 2 3 4 5 5 5 4 3 2 3 3 4 4 4 3 3 2 2 2 3 1 Scan 4 3 2 3 4 4 4 3 3 2 2 2 3 3 3 2 2 2 4 5 6 5 4 3 2 3 4 5 5 5 4 3 1 Scan 5 3 3 2 2 2 3 3 3 2 2 2 6 5 1 4 3 2 3 5 3 2 3 4 4 4 4 5 5 4 3 Scan 17 2 2 1 12/28/2010 8:47:59 AM Dr.Aravamudhan

Note the variation and intensities and the initial phases of the FID FT Spectrum FID 0 μs Scan 1 Scan 2 10 μs 15 μs Scan 3 20 μs Scan 4 Note the variation and intensities and the initial phases of the FID 12/28/2010 8:47:59 AM Dr.Aravamudhan

Acquisition time Detection time t2 5 3 2 3 3 4 4 4 3 3 2 2 2 3 3 3 2 2 2 8 1 6 4 2 1 2 4 5 6 4 3 2 3 4 5 5 5 4 3 3 2 2 10 μs 4 3 2 3 2 2 1 2 4 5 6 5 3 2 2 1 4 3 2 3 4 5 5 5 4 3 2 3 3 4 4 4 15 μs 1 2 4 5 6 5 4 3 2 3 5 5 4 3 2 3 3 4 4 4 3 3 2 2 2 3 3 3 2 2 2 1 4 5 3 3 2 2 2 3 3 3 2 2 2 4 5 6 5 4 3 2 3 4 5 5 5 4 3 2 3 3 4 4 4 1 20 μs 3 3 2 2 2 6 5 3 2 3 4 3 2 3 2 2 1 3 4 5 5 4 3 2 5 3 3 4 4 4 25 μs 170 μs 2 2 1 Acquisition time Detection time t2 There are 2 time axes and FT is carried out along both time axes The signal amplitudes as a function of time for the FID are stored in the memory for each delay time defining the evolution time t1 12/28/2010 8:47:59 AM Dr.Aravamudhan

t1 Amplitude of the signal as a function of t2 for the various evolution times t1 Matrix S (t1, t2) t2 FT along t2 axis S (t1, t2) S (t1, ν2) FT along t2 axis FT along t1 axis t1 S (ν 1, ν2) FT along t1 axis ν 1 ν2 ν2 12/28/2010 8:47:59 AM Dr.Aravamudhan

Magnetization vector precession y Pulse Pulse Reference Acquisition Real part spectrum x y x cos z The reference phases were exactly along the Axis, thus phase difference between signal and reference was 0,π/2,π or 3π/2 y y sin Magnetization vector precession Animated illustration of the variety of the FID waveforms. All descriptions are in rotating reference frames If the phase difference was not integer multiple of π/2, then ? Next sllde… y -x -cos y -y -sin 12/28/2010 Dr.S.Aravamudhan

t0 t1 ω1 t2 t3 t4 ω2 ω2 M0 y x (π/2)x (π/2)y My Evolution t1 (π/2)y R mixing (π/2)y Prepararion Acquisition t 2 My Evolution t1 (π/2)y M0 R Mc Mz y Only cosine component is acquired x t0 Red dots constitute time domain points along t1 t1 ω1 t2 t3 t4 ω2 ω2 12/28/2010 Dr.S.Aravamudhan