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Transmittance and optical constants of Ca films in the 4–1000 eV spectral range

Authors :: Angelo Giglia
José A. Aznárez
Stefano Nannarone
Daniele Bajoni
José A. Méndez
Luis Rodríguez-de Marcos
Sergio García-Cortés
Nicola Mahne
Manuela Vidal-Dasilva
A. Marco Malvezzi
Juan I. Larruquert
Fabio Frassetto
Luca Poletto
European Commission
Ministerio de Ciencia y Tecnología (España)
Consejo Superior de Investigaciones Científicas (España)
Source :: Digital.CSIC. Repositorio Institucional del CSIC, instname, Applied optics (2004, Online) 54 (2015): 1910–1917. doi:10.1364/AO.54.001910, info:cnr-pdr/source/autori:Luis Rodriguez-de Marcos and Juan I. Larruquert and Manuela Vidal-Dasilva and Jose A. Aznarez and Sergio Garcia-Cortes and Jose Mendez and Luca Poletto and Fabio Frassetto and A. Marco Malvezzi and Daniele Bajoni and Angelo Giglia and Nicola Mahne and Stefano Nannarone/titolo:Transmittance and optical constants of Ca films in the 4-1000 eV spectral range/doi:10.1364%2FAO.54.001910/rivista:Applied optics (2004, Online)/anno:2015/pagina_da:1910/pagina_a:1917/intervallo_pagine:1910–1917/volume:54
Publication Year :: 2015
Publisher :: The Optical Society, 2015.
Abstract: 8 págs.; 8 figs.; OCIS codes: (260.7200) Ultraviolet, extreme; (120.4530) Optical constants; (350.2450) Filters, absorption; (230.4170) Multilayers; (310.6860) Thin films, optical properties.<br />© 2015 Optical Society of America. The low expected absorption of Ca in the extreme ultraviolet (EUV) makes it an attractive material for multilayers and filters because most materials in nature strongly absorb the EUV. Few optical constant data had been reported for Ca. In this research, Ca films of various thicknesses were deposited on gridsupported C films and their transmittance measured in situ from the visible to the soft x-rays. The measurement range contains M2,3 and L2,3 absorption edges. Transmittance measurements were used to obtain the Ca extinction coefficient k. A minimum k of 0.017 was obtained at ∼23 eV, which makes Ca a promising low-absorption material for EUV coatings. A second spectral range of interest for its low absorption is below the Ca L3 edge at ∼343 eV. Measured k data and extrapolations were used to calculate the refractive index n using Kramers.Kronig relations. This is the first self-consistent data set on Ca covering a wide spectral range including the EUV.<br />We acknowledge support by the European Community—Research Infrastructure Action under the FP6 “Structuring the European Research Area” Programme (through the Integrated Infrastructure Initiative “Integrating Activity on Synchrotron and Free Electron Laser Science”) through proposal number Ref. 2007655. This work was also supported by the National Programme for Space Research, Subdirección General de Proyectos de Investigación, Ministerio de Ciencia y Tecnología, project numbers AYA2010-22032 and AYA2013-42590-P. L. Rodrí- guez-de Marcos and S. García-Cortés are thankful to Consejo Superior de Investigaciones Científicas (CSIC) for funding under the Programa JAE, partially supported by the European Social Fund. M. Vidal-Dasilva acknowledges financial support from an FPI fellowship number BES-2006-14047