OSA's Digital Library

Applied Optics

Applied Optics


  • Vol. 45, Iss. 1 — Jan. 1, 2006
  • pp: 137–143

Interface engineered ultrashort period Cr–Ti multilayers as high reflectance mirrors and polarizers for soft x rays of λ = 2.74 nm wavelength

Naureen Ghafoor, Per O. Å. Persson, Jens Birch, Fredrik Eriksson, and Franz Schäfers  »View Author Affiliations

Applied Optics, Vol. 45, Issue 1, pp. 137-143 (2006)

View Full Text Article

Enhanced HTML    Acrobat PDF (776 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



Cr–Ti multilayers with ultrashort periods of 1.39 2.04 nm have been grown for the first time as highly reflective, soft-x-ray multilayer, near-normal incidence mirrors for transition radiation and Čherenkov radiation x-ray sources based on the Ti–2p absorption edge at E = 452 eV ( λ = 2.74 nm ) . Hard, as well as soft, x-ay reflectivity and transmission electron microscopy were used to characterize the nanostructure of the mirrors. To achieve minimal accumulated roughness, improved interface flatness, and to avoid intermixing at the interfaces, each individual layer was engineered by use of a two-stage ion assistance process during magnetron sputter deposition: The first 0.3 nm of each Ti and Cr layer was grown without ion assistance, and the remaining 0.39 0. 72 nm of the layers were grown with high ion–neutral flux ratios Φ ˙ ( Φ Ti = 3.3 , Φ Cr = 2.2 ) and a low energy E ion ( E Ti = 23.7 and E Cr = 21.2 ) , ion assistance. A maximum soft-x-ray reflectivity of R = 2.1 % at near-normal incidence ( 78.8 ° ) was achieved for a multilayer mirror containing 100 bilayers with a modulation period of 1.379 nm and a layer thickness ratio of Γ = 0.5 . For a polarizing multilayer mirror with 150 bilayers designed for operation at the Brewster angle, 45 ° , an extinction ratio, R s / R p , of 266 was achieved with an absolute reflectivity of R = 4.3 % .

© 2006 Optical Society of America

OCIS Codes
(230.4170) Optical devices : Multilayers
(310.3840) Thin films : Materials and process characterization
(340.7470) X-ray optics : X-ray mirrors

Virtual Issues
Vol. 1, Iss. 2 Virtual Journal for Biomedical Optics

Naureen Ghafoor, Per O. Å. Persson, Jens Birch, Fredrik Eriksson, and Franz Schäfers, "Interface engineered ultrashort period Cr-Ti multilayers as high reflectance mirrors and polarizers for soft x rays of lambda = 2.74 nm wavelength," Appl. Opt. 45, 137-143 (2006)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. W. Knulst, O. J. Luiten, M. J. van der Wiel, and J. Verhoeven, "Tabletop soft x-ray source based on 5-10 MeV LINACs," in Proceedings of the Seventh European Particle Accelerator Conference (Austrian Academy of Sciences, 2000), pp. 2609-2611.
  2. H.-Ch. Mertins, F. Schäfers, H. Grimmer, D. Clemens, P. Böni, and M. Horisberger, "W/C, W/Ti, Ni/Ti, and Ni/V multilayers for the soft-x-ray range: experimental investigation with synchrotron radiation," Appl. Opt. 37, 1873-1882 (1998). [CrossRef]
  3. E. Spiller, Multilayer Optics for Soft X Rays (Plenum, 1986).
  4. D. L. Windt, "IMD: software for modeling the optical properties of multilayer films," Comput. Phys. 12, 360-370 (1998). [CrossRef]
  5. B. L. Henke, E. M. Gullikson, and J. C. Davis, "X ray interactions: photoabsorption, scattering, transmission and reflection at E= 50-30000 eV, Z = 1-92," At. Data Nucl. Data Tables 54, 181-342, (1993). [CrossRef]
  6. D. T. Atwood, Soft X Rays and Extreme Ultraviolet Radiation (Cambridge University Press, 1999), pp. 55-95.
  7. M. Yamamoto and T. Namioka, "Layer-by-layer design method of soft x ray multilayers," Appl. Opt. 31, 1622-1630 (1992). [CrossRef] [PubMed]
  8. F. Eriksson, "Soft x ray multilayer mirrors," Ph.D. dissertation (Thin Film Physics Division, IFM, Linköping University, Sweden, 2004).
  9. C. Engström, T. Berlind, J. Birch, L. Hultman, I. P. Ivanov, S. R. Kirkpatrick, and S. Rohde, "Design, plasma studies, and ion assisted thin film growth in an unbalanced dual target magnetron sputtering system with a solenoid coil," Vacuum 56, 107-113 (2000). [CrossRef]
  10. F. Eriksson, G. A. Johansson, H. M. Hertz, and J. Birch, "Enhanced soft x ray reflectivity of Cr/Sc multilayers by ion-assisted sputter deposition," Opt. Eng. 41, 2903-2909 (2002). [CrossRef]
  11. J. Als-Nielsen and D. McMorrow, Elements of Modern X Ray Physics (Wiley, 2001), Chap. 1, pp. 24-26.
  12. J. M. Freitag and B. M. Clemens, "Nonspecular x ray reflectivity study of roughness scaling in Si/Mo Multilayers," J. Appl. Phys. , 89, 1101-1107 (2001). [CrossRef]
  13. H. M. Hertz, G. A. Johansson, H. Stollberg, J. de Groot, O. Hemberg, A. Holmberg, S. Rehbein, P. Jansson, F. Eriksson, and J. Birch, "Table-top x ray microscopy: sources, optics and applications," J. Phys. IV 104, 115-119 (2003).

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited