Run a ¹H 1D spectrum and calibrate 90° pulse width

1. Follow the instructions in Sample Set-up

2. Create an experiment

Type edc to create an experiment. Enter desired values for NAME and EXPNO. Set USER to your user name and DU=u, PROCNO=1, TYPE=nmr.

Type rpar Stan1D to load a standard parameter set. Press COPY ALL. Type ii to initialize the instrument.

3. Tune the probe

Type acqu to go to the acquisition window. Type wobb and wait for a dip pattern to appear.

At the base of the magnet, carefully turn the yellow (¹H) knobs using the brass tool to adjust variable capacitors inside the probe. Observe the dip in the acquisition window or the LCD display on the preamplifier. Adjust the T knob to move the dip let or right; adjust the M knob to move the dip up or down. Adjust M and T iteratively until only green lights are lit on the LCD display.

Note: if a knob will not turn in one direction it is at the end of its tuning range. Do not force the knob to turn further or you will damage the probe.

4. Acquire and process a spectrum

Type zg to acquire an FID. Wait for the checklockshift:finished message.

Type ft to perform a Fourier transform. The water signal will be visible.

Type apk to automatically phase the spectrum.

Note: more detailed instructions on processing are available in Process a 1D spectrum.

5. Measure 90° pulse width.

Reacquire and process a spectrum by typing zg, then fp.

Increase the value of the excitation pulse by typing p1 and then entering a new value in µs.

Reacquire a spectrum (type zg and fp again).

Keep increasing p1 until the water peak is inverted (i.e., p1 > 180°) and is decreasing in intensity. As you approach the null you may have to press the *2 button to increase the vertical scaling of the display. Minimum intensity corresponds to p1 = 360°, generally between 40 and 50 µs. Divide this value of p1 by four to obtain the 90° pulse width.