The shape of NMR line obtained in recording the second derivative of the absorption line in polymers

The NMR of Polymers

“…H the form of the narrow component of the line is close to Gaussian, then the approximate limiting values are (3)(4)(5) A complex two-component structure is indicated by the appearance of four maxima on the curve of the second derivative of the absorption function. As was shown in our work [113], the re- gion characteristic of a two-component system is considerably greater when the second derivative is recorded than when the first derivative is used. For example, if for the Gaussian form of both components OHwide/oHnar = 3, then there will not be two maxima on the curve of the first derivative with any composition of the system, while on the curve of the second derivative there will be four maxima at a content of the mobile phase from 4 to 50%.…”

“…Second Derivative of the Absorption Function [113]. The characteristics of the form of the line appear very clearly when we record the second derivative of the absorption function.…”

“…It is found to equal h= ± ~ yl,r-a (3 cos 2 8 -1) (I- 113) i.e., less by a factor of one and a half than the effective value of the field produced by the interaction of like nuclei (I-111) and (I-112). i5] MAGNETIC INTERACTION Q' ATOMIC NUCLEI '71 By repeating the calculations performed for pairs of spins with the spin number % but with different gyromagnetic ratios ('Y 1 and 'Y2), we wruld obtain the resonance conditions in the form hrot,2='Vth [Ho ±-}'V2r-ah (3cosI6-1)]…”

“…Form of the second derivative of the line of the NMR spectrum[113]. a) Polymethyl methacrylate at room temperature; b) isotactic polypropylene at -196°C.…”

“…a) Polymethyl methacrylate at room temperature; b) isotactic polypropylene at -196°C. Form of the first (a, c, e, g) and second (b, d, f, h) derivatives of the line of the NMR spectrum of poly formaldehyde at different temperatures[113]. a,b) At -60·C; c,d) at -25"C; e.n at -20·C; g,h) at -10·C 157.…”