15. Analytical Techniques:IR, NMR, Mass Spect

(A true story.) A major university was designated as a national nuclear magnetic resonance center by the National Science Foundation. Several large superconducting instruments were being installed when a government safety inspector appeared and demanded to know what provisions were being made to handle the nuclear waste produced by these instruments. Assume you are the manager of the NMR center, and offer an explanation that could be understood by a nonscientist.

If two signals differ by 1.5 ppm in a 300 MHz spectrometer, by how much do they differ in a 500 MHz spectrometer?

If two signals differ by 90 Hz in a 300 MHz spectrometer, by how much do they differ in a 500 MHz spectrometer

Answer the following questions:

c. What is the relationship between coupling constant in hertz and operating frequency?

d. How does the operating frequency in NMR spectroscopy compare with the operating frequency in IR and UV/Vis spectroscopy?

(a) Calculate the resonance frequency of an aldehydic proton ( δ 9.3 ppm) if it is detected on a 60-MHz NMR spectrometer.

(b) What if it were detected on a 300-MHz instrument?

What strength magnetic field is required when a 500-MHz instrument is used for ¹H NMR?

Calculate the amount of energy (in calories) required to flip an ¹H nucleus in an NMR spectrometer that operates at 300 MHz.