Line-broadening factor

Usually, the FID is Fourier transformed after the application of an exponential window function (25). The line-broadening factor is selected to provide a good S/N. As a rule, the line broadening is selected according to the width of a narrow singlet resonance - in H NMR normally to a value from 0.1 to 0.5 Hz (cf. Figures 2 and 3). The resolution of the spectrum may be enhanced, though with reduced sensitivity, if the FID is multiplied, for example, by... 

Figure 2-8 The effect of multiplying a free-induction decay by a line-broadening factor of 3, 2, I, and 0 Hz. (Reprinted with permission from J. W. Cooper and R. D. Johnson, FT NMR Techniques for Organic Chemists, IBM Instruments, Inc., 1986.)...

A. Brown and J. W. Edmonds, The fitting of powder diffraction profiles to an analytical expression and the influence of line broadening factors, Adv. X-Ray Anal, 1980, 23, 361-374. 

In general, data was worked up using line broadening factors of 50 Hz or greater for 13C or IHz or less for IH. This is particularly important for solution 13C-spectra where signal to noise is poor. 

Figure 5. Changes in linewidth as measured by the line broadening factor LBF. triangles and calculated paramagnetic...

At the wavelength of 300 nm it will correspond to about 0.00001 nm, which is negligible in comparison with other line broadening factors. 

Figure 1 NMR spectrum of a guinea-pig heart perfused with Krebs-Henseleit solution. The spectrum was acquired at 8.7 T using a broad-band probe tuned to 145.8 MHz. Peak assignments are 1, phenylphosphonic acid (external reference) 2, phosphomonoesters 3, inorganic phosphate (P ) 4, phosphocre-atine (PCr) 5, y-phosphorus of adenosine triphosphate (ATP) 6, a-phosphorus of ATP 7, 5-phosphorus of ATP. The spectrum was acquired in 2.5 min by summing 72 free induction decays (FIDs) with a 35 gs pulse and a repetition time of 2 s. Prior to Fourier transformation the FID was subjected to exponential multiplication with a 20 Hz line broadening factor.

The rate of quadrupolar relaxation (Table 1) increases as the square of the NQCC. Line broadening due to a large value of Q may be offset by a large I value, the line-broadening factor being... 

For group VIII nuclei of spin > 1/2, relaxation should be dominated by the electric quadrupole mechanism. The rate depends on the correlation time, the square of the electric field gradient (efg) and the line broadening factor,... 

Line-broadening factor for quadrupolar nucleus N L = /(/a,) Ql, where / In) = 21 + 2, 1 1) Electron mass Proton mass... 

---