parameter

typical values

explanation

ACQUISITION 

[MHz]

C13, N15, P31

[sec]

2D: 0.2 to 0.8

length of FID; determines digital resolution: 
digital resolution = 1/at (without zero-filling)

note: at = np/(2*sw)

[points]

note: at = np/(2*sw)

[Hz]

note: at = np/(2*sw)

[Hz}

often replaced by DSP, therefore ‘not used’

number of transients after which data are sent from the console to the host computer

number of complete executions of the pulse sequence prior to actual data collection

[dB]

Note: for every 6 dB down, pw doubles

[msec]

length of a radio frequency pulse to rotate magnetization from z to xy-plane; depends on probe, tpwr, spectrometer

[msec]

often not used

[sec]

0.8 to 1.2 in 2D

relaxation time; allowing the magnetization to return to the z direction

[Hz]

solvent and field dependent

[dB]

sensitivity of the receiver; too high causes ADC overflow and serious baseline distortions

Note: for every 6 dB increase, the sensitivity doubles

4, 8, 16, 32, 64…

signal-to-noise increases with ; usually multiples of 4 or 8 required except for gradient-enhanced techniques where any integer is possible; for indefinite acquisition (runs until stopped by aa) enter 1e9

cannot be changed by user; if exp. runs to completion then ct = nt

s2pul is used for standard 1D spectra

SAMPLE

entered automatically by the system

directly affects tof and referencing of spectrum; read in with parameter sets and should not be changed unless solvent is not in the list

D2O and d2o etc. are identical (only for this parameter; this is an exception under UNIX!)

reads exp when an experiment is complete; when data are saved and read back, file shows the full name including the path

DECOUPLING

H1 for homonuclear exp.
C13 or N15 for gHMQC and similar exp.

[Hz]

for solvent presaturation set to solvent resonance; for heteronuclear decoupling set to middle of frequency range of decoupled nucleus; both depends on the field and the solvent (i.e. the lock frequency)

pulse sequences are divided into several time intervals (many have 3) and each letter defines whether the decoupler is on (at frequency dof and power dpwr) or off in the respective time interval

‘n’ for no decoupling, ‘y’ turns the decoupler on

for presaturation of solvent ‘c’; for broadband decoupling of entire nucleus ‘w’ (WALTZ) or ‘g’ (GARP)

inactive for dmm=’c’

[dB]

controls the power level of the decoupler channel; depends on solvent (for presaturation) and band width for heteronuclear broadband decoupling which is a function of the field strength

Note: for every 6 dB up, the power doubles

‘y’ for homonuclear decoupling, ‘n’ for heteronuclear decoupling, both require ‘y’ in the correct place of dm to turn the decoupler actually on