Molecular variation of capillary-produced soft x-ray high harmonics

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Vol. 41; no. 14; pp. 145602 - 145602 (8)
• Main Authors: Stebbings, S L, Rogers, E T F, de Paula, A M, Praeger, M, Froud, C A, Mills, B, Hanna, D C, Baumberg, J J, Brocklesby, W S, Frey, J G
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 28.07.2008; Institute of Physics
• Subjects: Exact sciences and technology; Frequency conversion ; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Nonlinear optics; Optics; Physics; X- and γ-ray instruments and techniques; X- and γ-ray sources, mirrors, gratings and detectors; Inorganic compounds; Soft X radiation; Optical phase matching; X-ray sources; Optical harmonic generation; Diatomic molecules; Nitrogen Molecules; Argon Atoms; Ionization; Coherent radiation; Waveguides; Optical frequency conversion; Triatomic molecule; Nonlinear optics; Higher harmonic
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/41/14/145602

The production of coherent soft x-rays via high harmonic generation (HHG) from Ar, N2 and N2O in a gas-filled capillary waveguide is reported. Odd harmonics of the driving laser intensity are observed as a function of gas pressure up to energies of 50 eV. By employing a simple phase matching theory that incorporates the spatial and temporal dependences of ionization within the waveguide, good agreement with the HHG spectral envelope has been obtained, indicating phase matching is the dominant factor in shaping the spectral envelope of the harmonics.