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A blog for the NMR users at the University of Ottawa and all others interested in NMR spectroscopy.
Glenn Facey
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- 1 (1)
- 1-ADEQUATE (1)
- 10B (1)
- 11B (5)
- 11B background (1)
- 11B COSY (1)
- 11B decoupling (1)
- 11B SQ/DQ correlation (1)
- 13C (3)
- 13C decoupling (4)
- 13C NMR of paramagnetic compounds (1)
- 13C satellites (2)
- 13C-14N (2)
- 13C-14N coupling (2)
- 13C-19F coupling (2)
- 13C-2H coupling (3)
- 13C-31P coupling (2)
- 13C-59Co (1)
- 14N decoupling (1)
- 15N (1)
- 17O NMR (2)
- 180 degree pulses (1)
- 19F (5)
- 19F decoupling (4)
- 19F-13C HMQC (1)
- 19F-1H HOESY (1)
- 1D HOESY (2)
- 1D HSQC (2)
- 1D NOESY (1)
- 1D TOCSY (2)
- 1H-11B HMQC (1)
- 1H-19F HOESY (1)
- 1H-2H coupling (1)
- 1H-31P HOESY (1)
- 23Na (2)
- 23Na background (1)
- 27Al decoupling (1)
- 29Si CP (1)
- 29Si DEPT (1)
- 2D NMR (38)
- 2H decoupling (1)
- 2H NMR (4)
- 31P (2)
- 31P decoupling (4)
- 31P-109Ag HMQC (1)
- 31P-13C HMQC (1)
- 51V (1)
- 59Co (1)
- 79Br (1)
- 90 degree pulse (4)
- accessing a used NMR magnet (1)
- acids (1)
- acoustic ringing (3)
- ADEQUATE (1)
- adiabatic decoupling (1)
- adiabatic pulses (2)
- air (1)
- antacid tablet (1)
- anthranilic acid (1)
- apodization (3)
- APT (1)
- ASA (1)
- ASCII data (2)
- background signal (3)
- background suppression (2)
- backward linear prediction (2)
- baseline correction (3)
- baseline roll (2)
- benchtop NMR (2)
- BIRD filter (1)
- Bloch Siegert shifts (1)
- Blood (1)
- broadband decoupling (1)
- broadband probe (1)
- broadening (1)
- butane (1)
- cable length (1)
- Canada (1)
- candy canes (1)
- CEST (1)
- chemical equivalence (1)
- chemical exchange agents (3)
- chemical shift referencing (3)
- chemical shift tensor (4)
- Christmas (7)
- cinnamon (1)
- citric acid (1)
- coffee (1)
- complexed solvents (1)
- composite pulses (2)
- concentration dependent chemical shifts (1)
- concentration gradient (2)
- contact time (2)
- cost of NMR probes (1)
- COSY (9)
- COSY 45 (1)
- COSY 90 (2)
- COSY vs TOCSY (1)
- coupling (7)
- coupling between magnetically equivalent nuclei (1)
- CP (23)
- CP vs Bloch decay (2)
- CPMG (1)
- cranberries (1)
- cryoprobe (1)
- D2O shake (1)
- data processing software (1)
- dead time (1)
- decoupler calibration (2)
- decoupling (7)
- decoupling bandwidth (2)
- DEPT (7)
- DEPT 135 (1)
- DEPTQ (1)
- deuterium (1)
- diffusion (1)
- digital filtering (1)
- diphosphate (1)
- dipolar coupling (2)
- dipolar dephasing (5)
- dirty probe (2)
- distortion (1)
- DNP (1)
- DOSY (2)
- double presaturation (1)
- double quantum filter (2)
- double quantum filtered COSY (1)
- DSS (1)
- dummy scans (1)
- dust (1)
- earth's field NMR (1)
- echo (1)
- ECOSY (1)
- edible oils (1)
- edited HSQC (1)
- effects of bad shimming (1)
- Eggshell (1)
- environmental instability (1)
- erroneous line shape specification (1)
- ethane (1)
- exchange (6)
- excitation profile (3)
- EXSY (2)
- external chemical shift referencing (1)
- EZNMR (2)
- fatty acids (1)
- FID (1)
- FID truncation (1)
- field dependence (2)
- field dependent resolution in solids (1)
- field homogeneity (1)
- floor vibrations (1)
- fluoride (1)
- FM radio station interference (1)
- forward linear prediction (2)
- Fourier transforms (3)
- fruit cake (1)
- FSLG (1)
- GARP (3)
- gas phase NMR (1)
- gated decoupling (1)
- ginger (1)
- gingerbread (1)
- Glycine (1)
- gradient calibration (1)
- gradients (4)
- H2BC (1)
- Hahn echo (1)
- half integer quadrupoles (8)
- hand cream (1)
- Hartman-Hahn match (2)
- heat dissipation (1)
- helium (1)
- helium fill (2)
- helium one-way valve oscillation (1)
- HETCOR (1)
- high power 1H decoupling (2)
- history of NMR (1)
- HMBC (7)
- HMQC (10)
- HMQC vs HSQC (1)
- HOESY (3)
- homonuclear decoupling (4)
- HSQC (11)
- HSQC-TOCSY (1)
- improving 2D NMR data (2)
- INADEQUATE (2)
- increasing signal-to-noise in MAS spectra (1)
- index (1)
- INEPT (2)
- inverse broadband probe (1)
- inverse gated decoupling (2)
- invisible 1H resonances (1)
- iPad apps (3)
- iPhone (2)
- isopropyl groups (1)
- isotope effect (10)
- J-Resolved (1)
- kinetic measurements (1)
- limonene (2)
- line broadening (2)
- line shape simulation (3)
- line shape specification (2)
- line shapes (2)
- linear prediction (4)
- liquid crystalline samples (1)
- lock (7)
- locking on the wrong solvent (1)
- locking with paramagnetic samples (1)
- lost signals (1)
- low-field (1)
- magnet (2)
- magnet quench (1)
- magnetic equivalence (2)
- magnetic field drift (1)
- malic acid (1)
- maple (1)
- MAS (16)
- MAS angle setting (2)
- MAS rotor crash (1)
- MAS sample size (1)
- MAS sideband suppression (1)
- MAS solids NMR vs solution state NMR (1)
- MAS spinning speed (2)
- missing or weak signals in DEPT spectra (1)
- missing signals in HMBC data (1)
- mixture analysis (4)
- molecular alignment (1)
- molecular motion (1)
- MRI (6)
- natural gas (1)
- nitrogen (1)
- nitrogen fill (2)
- NMR acronyms (1)
- NMR music (1)
- NMR of more than one isotope (1)
- NMR Technician (1)
- NMR time scale (1)
- NMR tubes (3)
- NOAH (2)
- NOE (4)
- NOESY (7)
- NOESY mixing time (1)
- NOESY vs ROESY (1)
- noise (1)
- non-uniform sampling (1)
- number of scans to collect (1)
- NUS (2)
- Nyquist sampling theorem (6)
- oxalic acid (1)
- paramagnetic oxygen (1)
- paramagnetic shifts (1)
- paramagnetic susceptibility determination (1)
- perdeuterated solvents (3)
- pharmaceutical analysis (1)
- phase (2)
- phase correction (3)
- phase errors (2)
- phases sensitive COSY (1)
- phosphate (1)
- Poor Shimming (1)
- popcorn (1)
- presaturation (6)
- probe (3)
- probe arcing (1)
- probe coil (1)
- probe electronics (1)
- probe tuning (10)
- protein (1)
- PSYCHE (2)
- pulse calibration (6)
- pulse power (4)
- pulse shape (1)
- pure shift NMR (3)
- Pure-Shift (2)
- purge pulse (1)
- QCPMG (5)
- quadrature detection (3)
- quadrature images (1)
- quadrature spikes (1)
- quantitative 13C NMR (1)
- quantitative 1H NMR (1)
- QUEST (1)
- radiation damping (2)
- ramped contact pulses (1)
- receiver gain (4)
- Red Blood Cells (1)
- reference deconvolution (1)
- relaxation time (5)
- relaxation time measurement (4)
- resolution (4)
- resolution enhancement (2)
- resolving overlapping signals (1)
- retrieving empty tube spinners (1)
- rf field (2)
- rf homogeneity (1)
- rhubarb (1)
- Rod Wasylishen (1)
- ROESY (1)
- ROESY vs NOESY (1)
- rotamer (1)
- rotational echo (1)
- rum and egg nog (1)
- sample depth (1)
- sample limitation (1)
- sample mixing (2)
- sample volume (1)
- satellite transitions (3)
- saturation (2)
- saturation transfer (3)
- scale of NMR spectrum (1)
- second order quadrupolar interaction (1)
- second-order (1)
- selective excitation (2)
- shaped pulses (5)
- shimming (5)
- shimming without a lock (1)
- shortbread (1)
- signal-to-noise (10)
- signs of coupling constants (2)
- silica (1)
- sinc distortion (1)
- slice selection (1)
- sodium (1)
- solid polymorphs (2)
- solid sample grinding (1)
- solid state 1H NMR (2)
- solid state 2H NMR (3)
- solid state NMR (1)
- solids NMR in a liquids probe (1)
- solution vs MAS solids NMR (2)
- solvent dependent chemical shifts (1)
- solvent suppression (3)
- sorbitol (1)
- sour (1)
- spectra without pulses (1)
- spin echoes (3)
- spin lock (1)
- spin noise (1)
- spin pairs (1)
- spinning (1)
- spinning liquid samples (2)
- spruce needles (1)
- steady state scans (1)
- sweeping field (1)
- T1 (4)
- T1 anisotropy (1)
- t1 noise removal (4)
- T1 rho (3)
- T2 (2)
- T2* (1)
- temperature calibration (2)
- temperature dependent shifts (1)
- temperature gradient (1)
- textbook (1)
- thermal noise (1)
- throwing away noise (1)
- TMS (1)
- TOCSY (3)
- TOCSY mixing time (1)
- TOCSY vs COSY (1)
- toothpaste (1)
- TRAPDOR (1)
- TROSY (1)
- tube thickness (1)
- Ultra-fast (1)
- unexpected signals in DEPT spectrum (1)
- variable temperature (5)
- video (7)
- virtual coupling (1)
- viscosity (1)
- Vitamin C (2)
- water suppression (5)
- watergate (2)
- weak lock (1)
- WURST (1)
- zero filling (2)
Blog Archive
-
▼
2008
(133)
-
▼
January
(15)
- Homonuclear Decoupling
- 1D TOCSY for Mixture Analysis
- Spinning Sideband Suppression in Solid State MAS NMR
- NOESY: Small Molecules vs Large Molecules
- Importing Bruker Data into MestReC 2.3
- Finding "Invisible" Protons with 27Al Decoupling
- 1H TOCSY
- Dipolar Dephasing as an Assignment Tool
- 13C Cross Polarization with Dipolar Dephasing
- 13C Showing J Coupling to Both 31P and 14N
- NMR Books
- National Ultra-high Field NMR Facility for Solids
- Proper Data Processing Can Be Very Rewarding
- Shimming Without a Lock Signal
- Searching for Small Peaks in 1H Spectra - 13C Deco...
-
▼
January
(15)
2 comments:
Please let me know why spin relaxation time is more for 13C nuclei which effect the integration of 13C spectra..
Naresh,
Thank you for the question. 13C T1's are generally longer and have more variability than 1H T1's. For the usually dominant dipolar mechanism, the 13C T1's are longer than 1H T1's because the relaxation rate depends on the product of gyromagnetic ratios for a given spin pair. For 13C, the dipolat relaxation rate would depend on gammaC*gammaH For 1H the relaxation rate depends on gammaH*gammaH which is 4 times greater than gammaC*gammaH.
The dipolar relaxation rates for carbon also depend on the reciprocal 6th power of the distance between the carbon and a proton. Since carbonyl carbons or quaternary carbons are far away from the nearest proton, their T1 relaxation times are very long (often tens of seconds or minutes) compared to protonated carbons where the T1's may be several seconds. This variability in 13C T1's means that in order to get a quantitative spectrum one must use very long recycle delays.
NOE's also cause a problem in obtaining quantitative 13C data.
Glenn
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