What are pulses in NMR?

In Fourier transform NMR spectroscopy and imaging, a pulse sequence describes a series of radio frequency pulses applied to the sample, such that the free induction decay is related to the characteristic frequencies of the desired signals.

How does pulse NMR work?

In the pulsed NMR method, the RF excitation is applied to the sample in a series of short bursts, or pulses. The application of the RF field for a short time (the “pulse width”) allows the applied torque to rotate the net magnetization kM by a specific amount.

What is the main role of sweep generator in NMR spectroscopy?

A sweep generator is a piece of electronic test equipment similar to, and sometimes included on, a function generator which creates an electrical waveform with a linearly varying frequency and a constant amplitude. Sweep generators are commonly used to test the frequency response of electronic filter circuits.

How can I improve my NMR resolution?

A chemical shift upscaling method is presented to offer better signal dispersion in NMR spectroscopy. Chemical shifts can be upscaled by a specific factor, while scalar couplings are unaffected. This approach allows rapid access of all spectral information.

How do pulse sequences work?

A basic pulse sequence There follows a hard radiofrequency pulse that excites the nucleus, transferring the magnetization into the x,y-plane. As the nuclei relax towards equilibrium they emit a radiofrequency signal known as the free induction decay (FID).

What is pulse angle?

Pulses are described using two parameters, the angle and the phase. Typically, the angle and the phase are shown above the pulse. The angle can vary from 0°-180° While the phase can take on values from 0°-360°​. Commonly the phase of the pulse is referred to the axis along which the B1 field is applied.

What is pulse width NMR?

Pulse width is the length of time that radiofrequency (RF) energy irradiates a sample in nuclear magnetic resonance (NMR) spectroscopy. The most important part is choosing the length of time for an RF pulse that produces the maximum signal.

What is the principle of sweep generator?

Explanation: In a Cathode Ray Oscilloscope, the sweep generator basically works on the principle of a capacitor. It generates linear rise time voltages by making use of the charging characteristics of a capacitor.

How NMR spectrum of a compound is generated by pulse FT NMR?

Fourier Transform NMR (FT-NMR): A method to collect an NMR spectrum in which a pulse of radio frequency energy is used to excite all nuclei of a particular isotope (1H, 13C, etc.) As the excited nuclei relax, they re-emit radio wave photons which produce an interference pattern called the free induction decay (FID).

What is the purpose of a pulse sequence MRI?

Among the most important pulse sequences in cardiac MRI are those used to obtain video images (‘cines’) of cardiac motion. The most commonly used cine imaging technique is called steady-state free precession imaging. This method offers high contrast between blood and myocardium, and no intravenous contrast is needed.

What is 90 degree pulse in NMR?

The 90º pulse-width (pw90) is the length of a pulse, usually in microseconds, that will produce the maximum response from a given NMR-active nucleus. The value of pw90 depends on the nucleus, pulse power (tpwr), probe tuning, and the research sample.