title: Single pulse coherence measurements in the water window at the free-electron laser FLASH.
abstract: The spatial coherence of free-electron laser radiation in the water window spectral range was studied, using the third harmonic (λ<(3rd) = 2.66 nm) of DESY's Free-electron LASer in Hamburg (FLASH). Coherent single pulse diffraction patterns of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) multilamellar lipid stacks have been recorded. The intensity histogram of the speckle pattern around the first lamellar Bragg peak, corresponding to the d = 5 nm periodicity of the stack, reveals an average number of transverse modes of M¯ = 3.0 of the 3rd harmonic. Using the lipid stack as a 'monochromator', pulse-to-pulse fluctuations in the third harmonic λ(3rd) have been determined to be 0.033 nm.
authors.affiliation: Institute for X-ray Physics, Georg-August-University Göttingen, Göttingen, Germany.
authors.forename: D D
authors.initials: DD
authors.lastname: Mai
authors.forename: J
authors.initials: J
authors.lastname: Hallmann
authors.forename: T
authors.initials: T
authors.lastname: Reusch
authors.forename: M
authors.initials: M
authors.lastname: Osterhoff
authors.forename: S
authors.initials: S
authors.lastname: Düsterer
authors.forename: R
authors.initials: R
authors.lastname: Treusch
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authors.initials: A
authors.lastname: Singer
authors.forename: M
authors.initials: M
authors.lastname: Beckers
authors.forename: T
authors.initials: T
authors.lastname: Gorniak
authors.forename: T
authors.initials: T
authors.lastname: Senkbeil
authors.forename: R
authors.initials: R
authors.lastname: Dronyak
authors.forename: J
authors.initials: J
authors.lastname: Gulden
authors.forename: O M
authors.initials: OM
authors.lastname: Yefanov
authors.forename: A
authors.initials: A
authors.lastname: Al-Shemmary
authors.forename: A
authors.initials: A
authors.lastname: Rosenhahn
authors.forename: A P
authors.initials: AP
authors.lastname: Mancuso
authors.forename: I A
authors.initials: IA
authors.lastname: Vartanyants
authors.forename: T
authors.initials: T
authors.lastname: Salditt