Interpretation:
The difference in the way a CW and an FT-NMR experiment is performed should be stated.
Concept Introduction:
Nuclear magnetic resonance is a technique that is used to predict the structural formula of the compound. NMR spectroscopy involves the examination of the nucleus under the external magnetic field.
Answer to Problem 19.1QAP
The CW spectometer scans a range of frequencies at a time while the FT-NMR scans all the frequencies. The plot between signal intensity and frequency is observed in CW experiment while the plot between signal and time is changed into the plot of signal and frequency by fourier transform.
Explanation of Solution
FT-NMR and CW corresponds to fourier transform nuclear magnetic resonance and continuous wave respectively.
In CW experiment, scanning of the sample is done by the spectrometer. It scans a range of frequencies. The interrogation of the sample takes place with one frequency at a time. The plot between signal intensity and frequency is observed as the frequency range is scanned.
In the FT-NMR experiment, the interrogation of the sample takes place with the range of frequencies. All the frequencies are interrogated at once. The decay of signal takes place with respect to time and it is observed as free induction decay. The plot between signal and time is changed into the plot of signal and frequency by fourier transform.
The CW spectometer scans a range of frequencies at a time while the FT-NMR scans all the frequencies. The plot between signal intensity and frequency is observed in CW experiment while the plot between signal and time is changed into the plot of signal and frequency by fourier transform.
Want to see more full solutions like this?
Chapter 19 Solutions
Principles of Instrumental Analysis
- Which method, AES or XPS, is better for resolving chemical shifts and why?arrow_forwardWhy does peak-splitting occur in NMR spectrum?arrow_forwardA H1 NMR signal is observed at 117.0 Hz (downfield of TMS) on a 1.20×102‑MHz instrument. a) What is the observed chemical shift in parts per million (ppm)? Chemical shift is ppm b) What is the chemical shift, in parts per million (ppm), if the sample is analyzed with a 60.0‑MHz instrument? Chemical shift is ppm c) Where will the proton signal appear, in hertz, if the sample is analyzed with a 60.0‑MHz instrument?arrow_forward
- How does the operating frequency in NMR spectroscopy compare with the operating frequency in IR and UV/Vis spectroscopy?arrow_forwardExplain the role of timescale of the experiment and the type of information you get from NMR.arrow_forwardWhat are the different names for 2D NMR experiments and what are they used for?arrow_forward
- Why inherent sensitivity of an NMR experiment is proportional to B02. Explain the origin of this dependence!arrow_forwardA signal is seen at 600 Hz from the TMS signal in an NMR spectrometer with a 300-MHz operating frequency. a. What is the chemical shift of the signal? b. What is its chemical shift in an instrument operating at 500 MHz? c. How many hertz from the TMS signal is the signal in a 500-MHz spectrometer?arrow_forwardWhen is 2D NMR usually used and why?arrow_forward
Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning
Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning
Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning