1990
DOI: 10.1107/s0108767389013875
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Direct measurements of triplet phase relationships of organic non-centrosymmetric structures using synchrotron radiation

Abstract: Recent progress in experimental triplet phase determination by the method of three-beam diffraction for 0108-7673/90/050393-10503.00 non-centrosymmetric light-atom structures is reported. The measurements were carried out with a special 0-circle diffractometer installed at the DORIS II storage ring in Hamburg. Experimental results O 1990 International Union of Crystallography 394 DIRECT MEASUREMENTS OF TRIPLET PHASE RELATIONSHIPS confirm the theoretical considerations. In general, the ~-scan profiles consist o… Show more

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Cited by 22 publications
(15 citation statements)
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“…Thus the incident radiation strikes several faces and a mixture of primary Bragg and Laue cases occurs. In spite of these adversities triplet phases can be measured with a precision of at least 45 °, as will be shown in the following paper (Hiimmer, Weckert & Bondza, 1990).…”
Section: Discussionmentioning
confidence: 94%
“…Thus the incident radiation strikes several faces and a mixture of primary Bragg and Laue cases occurs. In spite of these adversities triplet phases can be measured with a precision of at least 45 °, as will be shown in the following paper (Hiimmer, Weckert & Bondza, 1990).…”
Section: Discussionmentioning
confidence: 94%
“…In order to test the power of our method as a tool for quantitative triplet phase determination, we made measurements with several organic non-centrosymmetric small molecule structures with unit-cell volumes up to 3 nm 3 . The investigated structures are listed in Table 1 of the paper [8]. The result is that triplet phases can be experimentally determined from the three-beam diffraction profile with an accuracy of about 45 degrees -which means they can be assigned to phase octants with centres at 0 mod 45° -in spite of Aufhellung and Umweganregung effects, provided that these phase-independent parts are not the dominant effects.…”
Section: Resultsmentioning
confidence: 88%
“…Existence of such Umweganregung and Aufhellung effects were proved theoretically and experimentally by Weckert and Hummer [6] and Hummer et al [8]. A theoretical example is shown in Fig.…”
Section: Profiles With Umweganregung and Aufhellung Effectsmentioning
confidence: 97%
“…We note that experimental determination of phases is an active area of research (see, for example, Shen & Colella, 1986;Hiimmer, Weckert & Bondza, 1990;Spence, 1993), although the only useful results (for the purposes of charge density analysis) appear to be measurements of the phase of the 002 reflection (with estimated error 0.07 °) in CdS (Zuo, Spence & Hoier, 1989) and the 002 reflection in BeO [with estimated error 0.52 ° (Zuo, Spence, Downs & Mayer, 1993)]; for organics, triplet phases can be determined with an accuracy of -,~45 ° (Htimmer et al, 1990).…”
Section: Introductionmentioning
confidence: 99%