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Jonglin F. Tsao Sana R. Faruqi Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o57-o59
2,8‐Dioxatricyclo[3.3.3.01,5]undecane‐3,7‐dione, C9H10O4, (I), is the dilactone acylal of cyclopentanone‐2,2‐diacetic acid. Both molecules in the asymmetric unit have conformational chirality and differ principally in the flexing of the carbon ring, which produces a resolvable conformational disorder in one of the molecules. Three intermolecular C—H⋯O close contacts exist. 7,7′‐Oxybis(2,8‐dioxatricyclo[3.3.3.01,5]undecan‐3‐one), C18H22O7, (II), a racemate, lies on a C2 axis and is a non‐meso furanosyl furanoside dimer derived from the monoacid monoaldehyde corresponding to (I). One intermolecular C—H⋯O close contact exists. Diminished intramolecular void space in these small propellanoids generates unusually high crystal density in both species, particularly (I). 相似文献
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Yan X MacLeod AM Gillespie WA Knippels GM Oepts D van Der Meer AF Seidel W 《Physical review letters》2000,85(16):3404-3407
Time-resolved measurements of the transverse electric field associated with relativistic electron bunches are presented. Using an ultrafast electro-optic sensor close to the electron beam, the longitudinal profile of the electric field was measured with subpicosecond time resolution and without time-reversal ambiguity. Results are shown for two cases: inside the vacuum beam line in the presence of wake fields, and in air behind a beryllium window, effectively probing the near-field transition radiation. Especially in the latter case, reconstruction of the longitudinal electron bunch shape is straightforward. 相似文献
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