Poly-gamma-methyl-L-glutamate

Date:
1952
Reference:
PP/CRI/H/1/7
Catalogue details

Licence: In copyright

Credit: Poly-gamma-methyl-L-glutamate. Source: Wellcome Collection.

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    factor is of the form |F| exp* (n^ -t- a) where and » is the angular co-ordinate in reciprocal space xi is a phase angle» n is order of Bessel function involved. When we form ( PqFq ), our structure factor becomes P 2 exp. (2nlj/ 2a) Now we always have a set of 6 equivalent structure factors) related by symmetry, spaced at angular intervals of 2TT is reciprocal space. 6 The value at the origin of the distribution in real space whose transform is ( FqFq ) will be simply all the structure factors added together (just as Fooo* or isi n reciprocal If we now sum the above expression, vectorially, for all the 6 terms related by symmetry, we see that except when n is a multiple of 3 they all cancel. For example, if n = 2, if we start off with, say, 000' V1 , space, is all the electrons added together). and the next term is i nd with the third we get Ì which gives zero: and so also for the remaining three® When n is a multiple of 3? the vector is rotated a multiple of 2ir each time, and thus all the vectors add up. Thus the only terms which can contribute to the origin are the few weak ones on the layer line (the 6th* 9th etc. are absent) and the 1®5A reflection? and even these may