Coherent extreme ultraviolet (XUV) radiation produced by table-top high-harmonic generation (HHG) sources provides a wealth of possibilities in research areas ranging from attosecond physics to high resolution coherent diffractive imaging. However, it remains challenging to fully exploit the coherence of such sources for interferometry and Fourier transform spectroscopy (FTS). This is due to the need for a measurement system that is stable at the level of a wavelength fraction, yet allowing a controlled scanning of time delays. Here we demonstrate XUV interferometry and FTS in the 17-55 nm wavelength range using an ultrastable common-path interferometer suitable for high-intensity laser pulses that drive the HHG process. This approach enables the generation of fully coherent XUV pulse pairs with sub-attosecond timing variation, tunable time delay and a clean Gaussian spatial mode profile. We demonstrate the capabilities of our XUV interferometer by performing spatially resolved FTS on a thin film composed of titanium and silicon nitride.A well-known feature of high-harmonic generation (HHG) is broadband spectra in the XUV and soft X-ray regions [1][2][3]. This radiation is typically emitted in a train of attosecond pulses with excellent spatial and temporal coherence, as shown in various interferometric and spectroscopic measurements [4][5][6][7][8][9][10][11][12]. As a result, interferometry with high harmonics found important applications in e.g. Molecular Orbital Tomography [13], in wavefront reconstruction [14] and electric field characterization [15] of high harmonics. Recently, interferometry with high harmonics provided added value to coherent diffractive imaging (CDI) [16,17] using the full high harmonics bandwidth and photon flux. However, in the extreme ultraviolet (XUV) spectral range, interferometry and Fourier transform spectroscopy (FTS) are challenging due to the high stability requirements of the interferometer itself. Two main types of HHG interferometers have been devised. In one scheme, the near-infrared fundamental driving pulse is split into two phase-locked pulses with an adjustable time delay, and this pulse pair is subsequently used for HHG [5,[7][8][9]. Although this method has been successfully used it is typically limited by the stability of the optical interferometer. The other scheme is based on wavefront division, whereby one HHG beam is divided into two phase-locked sources by a piezo-mounted split mirror. This configuration allows more stable interferometry [10,[18][19][20][21], but results in two beams with different spatial profiles and strong diffraction effects due to the hard edge of the split mirror. Wavefront division interferometry is also less flexible when one would like to change the intensity ratio between the two beams.In this letter we present XUV interferometry using a novel ultrastable common-path interferome-1 arXiv:1607.02386v2 [physics.optics]

We report the demonstration of scanning-probe coherent diffractive imaging method (also known as ptychographic CDI) using a compact and partially-coherent gas-discharge plasma source of extreme ultraviolet (EUV) radiation at 17.3 nm wavelength. Until now, CDI has been mainly carried out with coherent, highbrightness light sources, such as 3rd generation synchrotrons, X-ray free-electron lasers and high harmonic generation. Here we performed ptychographic lensless imaging of an extended sample using a compact, labscale source. The CDI reconstructions were achieved by applying constraint relaxation to the CDI algorithm. Experimental results indicate that our method can handle the low spatial coherence, broadband nature of the EUV illumination as well as the residual background due to visible light emitted by the gas-discharge source. The ability to conduct ptychographic imaging with labscale and partially coherent EUV sources is expected to significantly expand the applications of this powerful CDI method. © Coherent diffractive imaging (CDI) is a rapidly emerging imaging technique to achieve diffraction-limited resolution without using imaging optics [1][2][3]. This makes CDI very attractive for imaging in the extreme ultraviolet (EUV) and X-ray spectral range, where the use of focusing optics is limited. In CDI, a coherent wave illuminating a sample produces a diffraction pattern related to the Fourier transform of the sample structure. While the magnitude of the Fourier transform (i.e. the square root of the diffraction intensity) can be collected by a detector, the phase information is lost, which constitutes the wellknown phase problem. If the diffraction intensity is properly measured, the phase information can be retrieved with an iterative algorithm and the sample structure can then be reconstructed [4]. With the rapid development of coherent X-ray sources worldwide, various CDI methods have been demonstrated and have found broad applications in both physical and biological sciences.One of the powerful CDI methods is termed ptychography (also known as scanning probe CDI) [5], in which an object is scanned relative to a structured illumination probe and a sequence of diffraction patterns is collected with an overlap between adjacent illuminated areas. In contrast to conventional CDI [1][2][3], ptychography uses the overlapping areas as a real space constraint, allowing the reconstruction of extended objects [5]. For high-resolution imaging, CDI and ptychography experiments typically employ large scale X-ray facilities, such as 3rd generation synchrotrons and X-ray free-electron lasers (XFELs) [1][2][3]. In the last decade, CDI and ptychography have also been successfully implemented with highly coherent tabletop femtosecond lasers generating EUV high harmonics [6][7][8][9][10].In this letter, we present an example of ptychographic imaging with a partially coherent compact gas-discharge EUV light source operating at 17.3 nm wavelength (Li-like oxygen, 1s 2 2p-1s 2 3d transition). In our gas-discharge light...

The spin and configurational structure of excited states of 127 Cd, the two-proton and three-neutron hole neighbor of 132 Sn, has been studied. An isomeric state with a half-life of 17.5(3) µs was populated in the fragmentation of a 136 Xe beam on a 9 Be target at a beam energy of 750 MeV/u. Time distributions of the delayed γ transitions and γ γ coincidence relations were exploited to construct a decay scheme. The observed yrast (19/2) + isomer is proposed to have dominant configurations of ν(h

Wavefront sensors are an important tool to characterize coherent beams of extreme ultraviolet radiation. However, conventional Hartmann-type sensors do not allow for independent wavefront characterization of different spectral components that may be present in a beam, which limits their applicability for intrinsically broadband high-harmonic generation (HHG) sources. Here we introduce a wavefront sensor that measures the wavefronts of all the harmonics in a HHG beam in a single camera exposure. By replacing the mask apertures with transmission gratings at different orientations, we simultaneously detect harmonic wavefronts and spectra, and obtain sensitivity to spatiotemporal structure such as pulse front tilt as well. We demonstrate the capabilities of the sensor through a parallel measurement of the wavefronts of 9 harmonics in a wavelength range between 25 and 49 nm, with up to λ/32 precision.

We report on the combination of a state-of-the-art energy-filtering photoemission electron microscope with an intense yet compact laboratory-based gas discharge extreme ultraviolet (EUV) light source. Using a photon energy of 71.7 eV from oxygen plasma (O5+ spectral line), we demonstrate element-selective photoelectron imaging in real space and band structure mapping in reciprocal space. Additionally, the high surface sensitivity of the EUV light was used to study the surface oxidation on islands of the phase-change material Ge1Sb2Te4. The EUV light source allows the extension of spectromicroscopy, previously only feasible at synchrotron beamlines, to laboratory-based work