Basic 1D NMR Experiment on Varian NMR Spectrometers

Parameter Description Example Std 1H experiment
tn transmitter nucleus 'H1'
sfrq observe transmitter frequency399.952 MHz
tof transmitter offset (center of spectral window) higher numbers set center of window to higher frequencies (downfield,higher ppm) tof=0 sets center of window to ~5ppm for 1H experiments -426.0 Hz
tpwr transmitter power (tpwr and pw determine how much signal is generated) 55 (range of 0 to 63)
pw pulse width 27 usec
sw sweep width 4400 Hz
dw dwell time, time between each data point (= 1/(2*sw)) 113.6 usec
fb filter bandwidth (=(1.25)(0.5)(sw)) 2640 Hz
np number of points, usually a power of 2 16384
at acquisition time 1.862 sec
fn number of pints to be fourier transformed (must be a power of 2, should be at least 2*np) 32768
dr digital resolution (=sw/np) 0.134
pad pre acquisition delay, the delay before the experiment starts 0
d1 relaxation delay, delay between transients 1
p1,d2 other pulses and delays not used in this expt 0
de delay between pulse and acquistion (=rof2+alfa) 30 usec
nt number of transients (or scans) =4n, where n=1,2,3… signal/noise ratio is proportional to nt2 16
bs number of transients to collect before saving data 16
ss steady state transients, pulses and delays are conducted but no data is collected during these transients 2
gain receiver gain, amount by which detected signal should be amplified to be observed. If gain='n', spectrometer will automatically adjust gain to the best value. 'n'

Apodization (Weighting) Functions

NameEquation
lorentzian exp(-t*pi*lb)
gaussian exp(-((t-gfs)/gf)2)
sine bell sin((t-sbs*pi/(2*sb)) where sb>0
squared sine bell sin((t-sbs*pi/(2*sb)) where sb<0

Helpful Hints:

movetof sets tof to cursor value.

movesw sets sw and tof based upon cursor values.

pw(60,<90 degree pw>) sets pw to 60 degree pulse width.

ernst(<T1>,<90 degree pw>) sets pw to Ernst angle ("ideal" pulse angle) where T1 = average T1 relaxation time of molecule

time(<hours>,<minutes>), sets nt so that experiment takes <hours>:<minutes>

dps to display pulse sequence

pps to plot pulse sequence


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Last updated: April 1st, 1998
URL: http://nmr.chem.indiana.edu/NMRguide/1dexpt/1d-para.html
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