Width increase effect

Effect of the monochromator s slit width on noise and resolution for the ultraviolet absorption spectrum of benzene. The slit width increases from spectrum (a) to spectrum (d) with effective bandpasses of 0.25 nm, 1.0 nm, 2.0 nm, and 4.0 nm. 

One of the most striking properties of humic acid is its change in free radical content upon conversion to the solid sodium salt. This change is reversible upon reacidification of the salt, the spin content returns to its original level (28). In general, the line widths increased about 50% on conversion to the salt. Table III illustrates this effect for many different humic acids. These results seem entirely consistent with the known properties of the salts of quinhydrone as shown in Figure 6 (28). 

For Cu(en) and Cu(nad) compounds the short-range magnetic order is achieved in low-temperature part of the investigated temperature region. At these temperatures the effective g-factor components are nearly constant whereas the resonance line width increases dramatically when the temperature decreases. 

In view of the remaining uncertainty, only the most recent work will be discussed. Stuart and Sutherland (1965), after a thorough study of many aliphatic alcohols, propose that Vb occurs in the range 1200-1330 cm in dilute solution. On the other hand, they find that the pure alcohols exhibit a broad association band which has been overlooked by all earlier workers because of its diffuse character. This broad band, which has two maxima near 1410 and 1330 cm implies a 10 percent shift in Vb and a band width increase to about 200 cm" upon H bond formation. Stuart and Sutherland conclude that the effects of H bonding on the deformation motions of the O—H group are quite complex and that steric effects, rotational isomerism, and interaction with C—H... 

For polymers, a number of authors have claimed that the peak width increases as the MW increases, but to discuss band broadening for polymers, several precautions are required. First, it is necessary to be sure that the injected solution is sufficiently dilute to prevent any viscous effect. (Practically no viscous effect is observable, even for narrow standards when WC < 0.1 for flexible polymers, this corresponds roughly to a concentration <1 mg/mL for MWs up to 500,000 for a higher MW, it is necessary to reduce the concentration.) Then, the real difficulty is to analyze very narrow standards for which polymolecularity is sufficiently low, so as not to participate in the peak width, or at least which polymolecularity is very precisely known. 

The advantage of Havriliac and Negami function is that the experimental data can be represented with a fair degree of accuracy using this function. But equation (9.03) is a 5 parameter equation, only three of which may be readily interpreted in terms of molecular quantities. (0) represents equilibrium behaviour, while (x>) represents instantaneous behaviour so that (0) - e(effective moment of the orienting unit. Parameter t is the jumping time associated with the jumping unit. However the exponents a and p are not well defined in molecular terms, while a describes the width of the dispersion, p describes the skewness of the dispersion width increases as a varies from 0 to 1 and skewness decreases as p increases from 0 to 1. 

Effect of addition of small solutes on BHI NMR mobility as observed from line-width increase (Lavoie, 1998). 

For analysis, let us assume that the concentration profile migrates inward as shown in Figure 16.1b with an error-function profile whose width increases in proportion to (time), and let us assume for a start that the stress state has no effect on the migration of potassium. Let us assume that the compressive stress at any point tends to rise because of this potassium concentration effect but tends to fall because of creep or relaxation of the glassy host. And let us assume that at small distances (less than 1 pm) from the surface, stress is relieved also by self-diffusion of the glass, so that right... 

---